SR Stutter and miss when engine is warm?

[BlackZenkiS14]

So I have a weird miss issue that only happens when the engine is warm. The car idles and maintains an idle at 900rpm without trouble.

When I first start the car, it will rev just fine. Like simply revving from 1.5-2k or 2.5-3k, however, once the engine is warm in operating temperature, it seems to miss or stutter when you blip the throttle. The issue gets worse as the engine gets warmer. And it is reflected in poor driveability during hard acceleration. when trying to accelerate it will just load up real heavy then finally snap up into power. Feels almost like a 2 stroke in the way the power comes on. Then when you shift into the next gear, it totally falls out of the power band and has to spool back up from nothing and is very laggy on power. (it only does this when warm, when tested with a cold engine (before reaching op temp), it snaps into power immediately upon shifting into next gear and lights up tires)

However, it rev's fine with the TPS unplugged, hot or cold. Can't find the connection to the problem.

I have rebuilt SR with 1k miles on it, JWT ECU, Splitfire ignition system, 740cc injectors, Z32 MAF, GTX2867R, S3 cams, NGK BKR7E plugs gapped to .025, and regular bolt on stuff.

*I have cleaned the MAF, cleaned the IACV, and checked for vac leaks.
*Plugs looked good, all a light brown/bronze/tan color, all equal across all 4 cylinders. (Brand new NGK BKR7EIX)
*All the gaskets are quality OEM, all on the engine are less than 1200 miles old. All were attached using brand new hardware, locking nuts with locking tabs. Intake gasket is brand new as well.
*Base timing is set to 15*
*TPS reads .5v when closed and 4.1v when WOT
*Tried a known good Z32 maf, no change.
*Swapped with a known good ignitor, same problem
*I replaced the Coolant Temp Sensor with a brand new OEM Facory Nissan part, and still the exact same thing. Revs great when cold, then begins to stutter and miss once it reaches op temp.
*I back probed the ECU at the CTS signal and confirmed that I am getting the appropriate reading there as well....1.2V.
*Checked codes, only code I get is the 55 "All Clear" Code.
*I also checked BOV, BOV is in good shape.
*The problem is the same with the O2 sensor plugged in, and unplugged.
*Replaced o2 sensor with brand new OEM unit, same problem.
*Swapped ignitors with a known good ignitor, and then tested my ignitor on another engine...same problems persist.
*Replaced TPS with brand new OEM TPS, same exact problem.
*Tried a new Enthalpy ECU tuned to the same specs, exact same problem in the same way.
*Tried unplugging knock sensor, makes no difference hot or cold.
*Tested a known good knock sensor and sub harness...problem persisted.
*Tested a known good set of OEM SR coil packs and sub harness, no change in problem.

Alright, here's a video that gives a pretty decent idea of whats going on. First 3 clips are of the engine cold, then a quick 2nd gear pull, then 3 clips of the stutter/hesitation issue after driving it for 5 min and doing a couple pulls. But if you notice, boost doesnt come on until like 4k and power doesnt come in until 4.5 or higher, which seems way laggy to me.

http://youtu.be/qDFuLn4zNbo

qDFuLn4zNbo

[jr_ss]

Sounds like a vacuum leak somewhere. What BOV do you have? Is it recirc'd? Have you checked TPS and MAF voltages?

[BlackZenkiS14]

I got all my vacuum leaks sorted out. I did have one.

I am running an hks ssqv, never had trouble before.

I have not checked voltages at either of those 2 sensors. How do I check? And what am I looking for?

[BlackZenkiS14]

I'll get a video of it tonight so you can understand the issue better.

[1990 sr hatch]

----bump----

[1990 sr hatch]

Instead of vrooooooooom
Its like vra-vroooooooom right? Lol
Believe i have the same issue
Ive changed cts
Cleaned maf
About to be changed intake gaskets and cleaning iac

[blksylv]

Could be the CAS going bad as well. I've went through two CAS and both had symptoms like you described. One got bad to the point where the car would randomly cut off.

[BlackZenkiS14]

Alright, here's a video that gives a pretty decent idea of whats going on. First 3 clips are of the engine cold, then a quick 2nd gear pull, then 3 clips of the stutter/hesitation issue after driving it for 5 min and doing a couple pulls. But if you notice, boost doesnt come on until like 4k and power doesnt come in until 4.5 or higher, which seems way laggy to me.

http://youtu.be/qDFuLn4zNbo

qDFuLn4zNbo

[jr_ss]

Have you pulled your plugs to see what they look like? Checked base timing? The TPS reset and voltages procedure is in the FSM.

Are your exhaust gaskets good, specifically the manifold to turbo one? That will cause slow spool. I had a bad waste-gate when I first swapped my motor in, boost didn't come on quick and I had a slight rattle, no miss though, which is probably part of the spool issue.

[BlackZenkiS14]

Have you pulled your plugs to see what they look like? Checked base timing? The TPS reset and voltages procedure is in the FSM.

Are your exhaust gaskets good, specifically the manifold to turbo one? That will cause slow spool. I had a bad waste-gate when I first swapped my motor in, boost didn't come on quick and I had a slight rattle, no miss though, which is probably part of the spool issue.
Plugs looked good, all a light brown/bronze/tan color, all equal across all 4 cylinders.

All the gaskets are quality OEM, all on the engine are less that 1500 miles old. All were attached using brand new hardware, locking nuts with locking tabs. Intake gasket is brand new as well.

Base timing is set to 15*, set just a week ago.

TPS reads .5v when closed and 4.1v when WOT

[jr_ss]

How many grounds do you have?

[BlackZenkiS14]

I have all the factory ones, plus two more added. One added from valve cover to chassis then one from intake manifold to chassis.

[jr_ss]

So unusual for this to just "pop" up. It only does it after the engine is warm?

Do you have anyone local or spare parts? Try a different ignitor.

[ultimateirving]

Wastegate lazy? Just trying to think of odd ball things.

[BlackZenkiS14]

So unusual for this to just "pop" up. It only does it after the engine is warm?

Do you have anyone local or spare parts? Try a different ignitor.

Well, it started doing it the day the engine blew up, about a month ago. I attributed it at the time to the #4 cylinder being dead. However, now I have a full fresh engine with only 1k miles on it, and it does it when its warm only.

I might just start swapping parts around and see what happens...yea.

[jr_ss]

The reason I mentioned ignitor is because it's pretty common for them to start failing once hot. My friends MKIV had a similar issue. Ran fine when the car was cold, once it warmed up, it would break up and miss like crazy. It's just a thought that it may be a similar circumstance.

[BlackZenkiS14]

Yea, I can give that a try, Im going to try replacing the CTS first and see what I get!

[BlackZenkiS14]

Well, I ordered new factory OEM Coolant Temp Sensor, and we'll see if that fixes it! Then i'll just have to figure out where the fuck all the oil is coming from, it leaks like crazy

[KoukiMonsta]

Hmm, when I talked to you before I was thinking you had a tune related issue. But you have a can of works huh man.

Coolant temp sensor, cheap and easy to swap.

Take the tps voltage down to around .45v. Iirc .5 is too high to set the flag for closed Tb. This may help your low idle but I doubt it helps the stutter. Edit: more I think about it I believe it needs to be under .55 so your probly good

Ignitor and CAS would be my other thoughts. I'm with jr_ss about ignitor a going out when hot. Especially if you have it in the bay still. An old setup of mine did that. Basically it would stop running when hot. New ignitor fixed it. The CAS can do funny things. Easy enough to test if it's getting power/grnd.

Do you have any ecu codes?

[quickdiversion]

I have the same blowoff valve so this is why I am bringing this up.

At ECB last year I was reving off with a buddy that has a vet, keeping the motor high in the rpm, 6-8k for a good amount of time. As I am sure you know this would be the same as a single drift. My point is my ssq faces downward so I can't see into it. I was having a huge vacuum leak and power lose after. The face on the piston, the part that pushes closed came off the piston. It was actually sitting on a funky angle and leaking like a mother.

That was a huge vacuum leak, and like I said it faces down, so I never saw it or thought to check it. till for some random reason I took it off to clean it. I think I was looking for an oil leak.

Anyway, give it a look and make sure it is closed all the way.

http://i12.photobucket.com/albums/a206/quickdiversion/20120701_190207.jpg (http://s12.photobucket.com/user/quickdiversion/media/20120701_190207.jpg.html)

[BlackZenkiS14]

Well, I replaced the Coolant Temp Sensor with a brand new OEM Facory Nissan part, and still the exact same thing. Revs great when cold, then begins to stutter and miss once it reaches op temp. What's next?

Checked codes, only code I get is the 55 "All Clear" Code.

I also checked BOV, BOV is in good shape.

[WristWork]

Try spraying soapy water at the intercooler piping welds, BOV Flange. Mine is leaking at the welds on the bov flange and the flange itself, I have an HKS like the one above

Also try a new ignitor
Also I noticed on your video your bov doesn't have the adjustable nut? that can also be something to check on

My car has been runing weird too and I get the same 55 code

[jr_ss]

Try a different ignitor.

Cough, cough...

[steve shadows]

Definitely sounds like ignition /thread

:w00t:

[1990 sr hatch]

Yeah... You probably shouldn't spray water on the pipes, what happens when your try to combust that soapy water. Use carb,brakleen. But im positive its not a vac leak im having same ssues on my sr stock ecu , maf, fmic gotta be some thing ignition wise.

[BlackZenkiS14]

Definitely sounds like ignition /thread

:w00t:

Im all ears on what you think it might be, but its brand new plugs and new Splitfire ignition system.

I have not tried a different ignitor, but I guess that'll be the next step...

[1990 sr hatch]

Im gunna try igniter on mine tomorrow probably ill keep you updated

[BlackZenkiS14]

Im gunna try igniter on mine tomorrow probably ill keep you updated

Definitely man, please do.

The reason that makes me think its not the ignitor, is that my ignitor is in the very corner of my engine bay on the intake side, so not hardly any heat even gets over there.

And its not a matter of things getting hot, literally the problem follows the temp gauge, as soon as it reaches operating temp is when the issue pops up.

[KoukiMonsta]

Based off that previous post, what would happen if you run it with CTS unplugged?

To be clear, I'm sure it's unnecessary, but we are talking about the 2 wire sensors for ecu correct?

If you run it unplugged do you get a code for it?

I'm not too familiar with split fire. How hard would it be to swap back oem cool packs for testing?

[cotbu]

Based off that previous post, what would happen if you run it with CTS unplugged?

To be clear, I'm sure it's unnecessary, but we are talking about the 2 wire sensors for ecu correct?

If you run it unplugged do you get a code for it?

I'm not too familiar with split fire. How hard would it be to swap back oem cool packs for testing?

If you're lucky the engine will start and you won't get a code, until you shut the engine off, once you get the code the engine wont start. Drive cycle is about 2-5mins till the sensor gets registered again.

If you unplug the sensor and try to start the car(try meaning the engine doesn't fire) you get the code right away and it won't start.

That is based on a fully functioning ecu!


Not hard the sr20det split fire coil packs are a plug and play jobby job.

[1990 sr hatch]

Or if you have a voltmeter
A proper working cts reads at
°f 68 2100-2900ohms
°f 122 680-1000ohms
°f 176 300-330ohms
To test sensor, disconect sensor connector. See engine (coolant) temp sensor location table. Measure resistance across sensor connector terminals .if resistance is not as specified in engine (coolant) temp sensor risistance table, replace sensor

[BlackZenkiS14]

I already replaced the CTS with a brand new OEM unit.

The problem was there with the factory ignition as well as the splitfire. Upgrading to splitfire was one of the things I did to try to remedy it initially because my coils were all cracked.

[Mikester]

Kyle- did you say your plugs were a bronze/tan color? PLEEEASE tell me you don't use any additives.
I had a very nearly similar issue with my SR back in Okinawa... The short version of the story is that I swapped pretty much every fucking thing on the motor that you could possibly think of that could cause this issue... Of course thanks to that f####t Capt. Murphy the extreme last thing one tries is usually the thing that fixes the problem LOL- turned out to be my ECU warm loop was faulty... Brand spanking new power FC fixed it and I never looked back...

Given that power FC is pretty old and AEM infinity is modern and VERY AWESOME Albeit expensive... I think you need a new ECU (ahem... And dyno tune... Cough)

:-D

[quickdiversion]

I second Mike's opinion. At least try another know working ecu for testing.

[KoukiMonsta]

I'll third that opinion, cuz he said dyno!!!

In all seriousness if you can test a local ecu do it asap. This is starting to sound like the answer.

[BlackZenkiS14]

Its a tuned and calibrated JWT ECU, not something I can simply swap out.

[quickdiversion]

You call them all of you can send them the ecu for testing, or swap for one. You can also go through with them all that outs going wrong and what had been done. Tell them the ecu I all that's left and see what they offer?

[BlackZenkiS14]

Well, I back probed the ECU at the CTS signal and confirmed that I am getting the appropriate reading there as well....1.2V.

Also the problem is the same with the O2 sensor plugged in, and unplugged.

[cotbu]

I listened to your video and it sounds like spark is be cut out by something, fuel, water or oil maybe. Right after you get it to have the problem, shut it down and pull the plugs. I see you've pulled codes already. So it's not a true misfire or a misfire registered by the ecu or timing would be pulled and you said timing is still 15deg.

Disconnecting your tps, during your test should give the same results, a lazy throttle response. You could try clearing long/and short term fuel trims and set the tps to .445/.45v not .50v. That's an acceptable working range, only if it's registering closed and or the ecu has relearned.

The other option is to let the car get up to operating temp without touching the throttle, the first time you touch the throttle after completely warm, does it still stutter or miss?
If so, pull the plugs, do not idle excessively, you need to pull the plugs when the problem occurs.

[S14DB]

I already replaced the CTS with a brand new OEM unit.

The problem was there with the factory ignition as well as the splitfire. Upgrading to splitfire was one of the things I did to try to remedy it initially because my coils were all cracked.

Spitfire doesn't replace the ignitor. It just bumps the power up on the constant.

[ultimateirving]

Spitfire doesn't replace the ignitor. It just bumps the power up on the constant.

Yup. The ignitor could still be heating up and failing. Have you tried a new one yet

[jr_ss]

I've been pointing at the ignitor since day one... Doesn't seem like he has looked into that aspect of it yet. In for updates.

[BlackZenkiS14]

I havent, as I dont have easy access to testing a new ignitor.

But I cant imagine thats the problem, because the car runs perfect until operating temperature is achieved, like clock work. like if I start it, let it idle until car is at operating temp, the issue will be there.

Its not like the engine bay needs to get hot, or the ignitor needs to heat up or anything, the ignitor is the in the very corner of hte engine bay on the intake side, away from all heat.

[jr_ss]

The ignitor still gets hot, regardless of its location. It's an electrical conductor with voltage constantly going through it.

PM me, I have a spare ignitor. I'll let you use it to test just send me a deposit. If it happens to be the problem you can keep it and we have the problem solved. If not you can mail it back and I'll return the deposit.

[BlackZenkiS14]

The ignitor still gets hot, regardless of its location. It's an electrical conductor with voltage constantly going through it.

PM me, I have a spare ignitor. I'll let you use it to test just send me a deposit. If it happens to be the problem you can keep it and we have the problem solved. If not you can mail it back and I'll return the deposit.

Thanks a lot for that offer man, good dude. But I've got a couple friends within driving distance of me that I can probably try to snag one from, just haven't had time to get out and do it yet.

I've got my Nissan DataScan and PLMS cable coming in in a couple weeks that should help get it sorted out.

[jr_ss]

I'm sure Mike would be willing to let you "try" his if he is around. Besides, it sounds like he's going away for awhile.

[Mikester]

I'm sure Mike would be willing to let you "try" his if he is around. Besides, it sounds like he's going away for awhile.



Yup- I will be home this weekend... Weather permitting, me & the 240 will be going on a date lol. Will be happy to meet ya Sat or Sun if you wanna give mine a whirl... Beyond that, get with Andy & tell him I said it's cool- he has my keys anytime I'm gone for more than a couple weeks & after this weekend, I will be gone till August.

I still suspect it's the ECU. JWT ECU's are still 20+ yr old SR ECU's... With a tune & maybe some copyrighted goodies added. Even if the whole board were brand new, they can still fail... Especially given Kyle's 'less than ideal' luck (much love broham lol)...

Had the same issue... Or at least a strikingly similar one.

Kyle- I sincerely hope it's the igniter.... But my gut still says ECU.


Mike

[quickdiversion]

I think I still have my old ignitor that I know works, cause I switched to ls2 coil packs. let me know if the ignitor fixes it, you can have it.

Mike, you being deployed again?
I texted you week, where ya been?

[Mikester]

Bryan- been at SNCOA in Alabama.

Kyle- fixed??? If so, do tell.

[BlackZenkiS14]

Well it wasn't the O2 sensor, I have the Nissan DataScan program, but I need a new laptop, mine shit the bed. And I need help translating the data, Cody has been helping but he's been busy lately.

I'm gonna try to get to the dyno soon and get a few pulls for more intel

[Mikester]

Did you ever get back with JWT? Why pay for dyno time when you know it stutters & misses when warm? I am off all next week, will be happy to watch your boost, AFRs etc. any evening on a long straight road :-)

[BlackZenkiS14]

Might take you up on that, but yea, JWT has been trying to help walk me through it as well.

[BlackZenkiS14]

Still no resolve. Same problem, gets worse in warmer temps as I noticed today.

Any fresh ideas?

[bataangpinoy]

This is happening to my s15 sr, but in reverse. It will randomly misfire and cut out as the temps get colder (ie if it gets cold at night). Sometimes it runs great, others, it will break up or cut IGN completely. In my car, it feels like IGN cut; fuel pressure is stable whenever it happens, as is boost level.
Leads me to believe its either a failing maf, or that I'm maxing my stock maf (if thats even possible).

In your scenario, being that it occurs when getting up to operating temp and its not your CTS, I am led to believe that a failing CAS is the culprit.I would open it up and inspect it...

[jr_ss]

Still no resolve. Same problem, gets worse in warmer temps as I noticed today.

Any fresh ideas?

Can you update on what you have tried? That way people don't offer same advice, such as ignitor... :rant2:

[BlackZenkiS14]

This week I am going to try to locate a new igniter and a new CAS to try. But here is what I have done so far.


I have cleaned the MAF, cleaned the IACV, and checked for vac leaks.
Plugs looked good, all a light brown/bronze/tan color, all equal across all 4 cylinders.
All the gaskets are quality OEM, all on the engine are less than 1200 miles old. All were attached using brand new hardware, locking nuts with locking tabs. Intake gasket is brand new as well.
Base timing is set to 15*, set just a couple weeks ago.
TPS reads .5v when closed and 4.1v when WOT
I replaced the Coolant Temp Sensor with a brand new OEM Facory Nissan part, and still the exact same thing. Revs great when cold, then begins to stutter and miss once it reaches op temp.
Checked codes, only code I get is the 55 "All Clear" Code.
I also checked BOV, BOV is in good shape.
I back probed the ECU at the CTS signal and confirmed that I am getting the appropriate reading there as well....1.2V.
Also the problem is the same with the O2 sensor plugged in, and unplugged.
Replaced o2 sensor with brand new OEM unit, same problem.

[KoukiMonsta]

Damn, was really hoping your post would be "I found the solution"

I am doubtful the CAS would be the culprit, based on its internals and design I don't exactly see temp effecting it.

I am still leaning towards ignitor, as it seems much more plausible especially with a past experience of mine. (pretty sure i mentioned it in this thread..car got hot...things went shitty)

Did JWT have any good leads for you? besides the stuff you posted?

I will be mind blown if its not ecu or ignitor related, considering all the testing and part swapping you have done. I just cant see what else may be the culprit - since this seems to be temp based...

That gives me a thought though, 'temp based' - as in temperature sensed by a sensor (CTS) or temp as in the engine bay heats up and components (ignitor) do weird things.

Just hoping to spark a thought or answer with some brainstorming, I kinda want to see that new turbo in action..

[BlackZenkiS14]

Tell me about it man, thanks for the intelligent thought!

I'm gonna start swapping things, and start logging some more stuff on Nissan DataScan and then go back to JWT if I am still having issues.

[BlackZenkiS14]

FML. Someone help me lol

Swapped ignitors with a known good ignitor, and then tested my ignitor on another engine...same problems persist.

Also, when you shift into the next gear, it totally falls out of the power band and has to spool back up from nothing and is very laggy on power. (it only does this when warm, when tested with a cold engine (before reaching op temp), it snaps into power immediately upon shifting into next gear and lights up tires)

[delado]

what do your AFR's look like when the break up happens? Maybe something to do with that tune?

[BlackZenkiS14]

I mean, possibly, but I ran the tune for 3 years previously with no issues....

[inopsey]

how old are your plugs? i read your original post and you said they are the right color but have you recently/since this started changed them?

[Mikester]

Plugs looked good, all a light brown/bronze/tan color, all equal across all 4 cylinders.


Your plugs being a brown/bronze color tells me they are cooked... Same color they get after someone drops in some injector cleaner, octane booster etc. I'd change those first... They should be a slight dark grey, light blackish color.

Second of all, when are you going to come to terms with the fact that your ECU is probably the MAIN culprit and you are spinning your wheels throwing parts at it? This was the SAME EXACT problem I had with my 180SX... replaced everything INCLUDING the CAS... Problem magically went away when I pulled the ECU out and replaced it with a shiny new Power FC.

Going back to your plugs, they should not be bronze/brown.

[BlackZenkiS14]

http://kereta.info/wp-content/uploads/2009/07/spark-plug-colour.jpg

Not sure what you mean Mike?

But thanks for the attempted advice, I am working with JWT to figure this out as well. I appreciate you trying to help me from "throwing parts at it", but I'm not just going to "throw a $1k ECU at it" to fix it either. There are TONS of people running this setup, WITH the JWT ECU, and doing very well for a long time. I'll get it figured out eventually.

Plugs are as old as this engine is. Only 1500 miles.

[Mikester]

Kyle, I don't think your plugs are THE problem, I said it could be A problem. When you said bronze/brown, that's not what I had envisioned.

If there are tons of people running the very same setup, maybe someone will loan you their ECU... Until then, I hope by working with JWT you mean you sent them back your ECU for indepth testing. No disrespect brother. You know I'm all about helping a dude out. If you've the car at events, then 1500mi might be worth the 30-40 for fresh plugs. My PFC will be back next week, we have very similar setups- you're welcome to try mine.

[Mikester]

And by the way, you've been letting this issue kick your ass & expending time & money on it for almost 3mos based on the start date of this thread. If I were you, I'd welcome any 'attempted advice' given at this point. Trying to help man. I'd like to compare slips & I leave in 3-4 weeks.

[BlackZenkiS14]

I know you are trying man, and I appreciate that, but just saying "its your ECU, buy a PFC" really isnt a feasible option at this point man.

I dont have $1k to spend on an ECU, and I dont want a PFC that I have to pay someone else to tune for me that lives out of state...

The only money I've spent on this so far is a new CTS ($20), and a new O2 sensor ($50)

I just might try throwing in a set of Iridium plugs and see what happens. I've run iridium plugs my whole life, and this is my first time ever using copper.

[jr_ss]

I don't think Mike is blaming the the tune, more so a circuit in the ECU itself.

It's pretty simple to pull the EPROM out and have it swapped to another ecu. I'd start with cracking the case open and seeing if you see any burnt or charred traces.

[BlackZenkiS14]

I don't think Mike is blaming the the tune, more so a circuit in the ECU itself.

It's pretty simple to pull the EPROM out and have it swapped to another ecu. I'd start with cracking the case open and seeing if you see any burnt or charred traces.

Looked good to me so far. Also sent these to JWT

http://i228.photobucket.com/albums/ee147/KyleCrangle/20140912_164212_zpsvtfw4fzq.jpg (http://s228.photobucket.com/user/KyleCrangle/media/20140912_164212_zpsvtfw4fzq.jpg.html)

http://i228.photobucket.com/albums/ee147/KyleCrangle/20140912_164315_zpszwz8z6yk.jpg (http://s228.photobucket.com/user/KyleCrangle/media/20140912_164315_zpszwz8z6yk.jpg.html)

http://i228.photobucket.com/albums/ee147/KyleCrangle/20140912_164339_zpsd5k0fi2y.jpg (http://s228.photobucket.com/user/KyleCrangle/media/20140912_164339_zpsd5k0fi2y.jpg.html)

[jr_ss]

I agree that it does look good. A better picture of the last one would be great. I think I may see something, but then againit could be nothing at all. Regardless, it is very puzzling.

[BlackZenkiS14]

Yea, I didnt realize the last one was blurry until I uploaded it lol

Im going to try to get the car to a dyno today actually and see what that graph looks like also, see if I'm losing power in the powerband also, or just between shifts.

Ben Pila at JWT is working with me and the engineer there looking at my data logs, so hopefully they can come up with something for me.

Just so frustrating, I've missed a lot of events this year, mostly because I've been too busy to work on the car to fix it, but if it was fixed I'd have been able to go.

[Mikester]

Kyle- not saying to get a PFC... There are WAY better & more powerful options these days... Just saying that even a 'new to you' ECU with the same JWT tune will probably fix the issue. I know I sound like a broken record- it's only because I had the exact same problem with my 180SX. Is it an E-series ECU (Chuki Blacktop) by default?

[BlackZenkiS14]

Yea, we will see what Ben at JWT says. I'm open to anything.

Also, found today that even with the issues, it still makes power....plenty of it! haha

https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-xfp1/v/t1.0-9/10590659_10154566938185043_1002561199502155733_n.j pg?oh=4dbdcdcdd7e5f1ce8a93f33324e21b99&oe=54CEB98C&__gda__=1422787305_9c882e641e30facc914455700cfb24f 3

[metako42]

I mention this because no-one has bought it up but it could be your injector O-rings leaking fuel into the combustion chambers when they get hot. They might just be holding the seal when cold but give them some heat and they might be not sealing. This would normally give a black plug but you never know. Also have you removed each injector wire in turn whilst idling to work out which cylinder is the culprit? Then swap injectors to see if the problem moves with it.

[BlackZenkiS14]

I cant imagine that would be the issue, the injectors were rebuilt and flow tested with all o-rings replaced by Witch-Hunter just 1500 miles ago.

Thanks for the idea though!

[BlackZenkiS14]

Well, I installed a known-good Z32 MAF and a known-good SR CAS. No change in the issues.

Whats next? :(

[cotbu]

I forgot you're spraying, try shutting off the alcohol mix completely to eliminate the water as a contaminant. Turn it back on after you confirm.

Sent from my Highly Tuned Galaxy S3.4!!!

[BlackZenkiS14]

Will do. But that would be weird for that to be the problem, because its temperature sensitive...and the meth pump/everything is wired in totally separate of the ECU. But I'll give it a shot.

[Mikester]

I see your ECU is an E5... Same as my 180's was :p

Nice numbers bro!!!

[BlackZenkiS14]

I see your ECU is an E5... Same as my 180's was :p

Nice numbers bro!!!

I am hoping JWT asks me to send the ECU in for check, but at this point they have not asked for it.

[BlackZenkiS14]

Well 20+ emails, 12 logs, and 3 months later I finally get this from JWT:

"Our lab engineer says he will make a revised test EPROM with the changes based on your latest logs sent. We will then mail that to you so you can switch it out and see how it runs. "

haha who knows what they think it is, but man it would be sweet if that fixed it!!

[jr_ss]

Agreed... Based on all the testing it had to be a hard ware issue.

[Mikester]

Hey Kyle- so I wonder... Isn't EPROM-



IN THE FUCKING ECU????

There went your free pizza!

77550

[BlackZenkiS14]

Thanks Mike, that was very helpful.

I never said there was no way it was in the ECU, I just had to be patient with JWT to get back to me. I couldnt just swap ECU's lol

[Mikester]

Just bustin your chops brother. Given your luck, I'm glad JWT is working it- will be stoked to see your car run how it should have all along [emoji106]

[BlackZenkiS14]

Just bustin your chops brother. Given your luck, I'm glad JWT is working it- will be stoked to see your car run how it should have all along [emoji106]

Yea, I'm curious lol, since I made 419 to the tires with issues ;)

[unometeeter]

Coil could be getting hot and breaking up spark, when the engine warms up.

[jr_ss]

Coil could be getting hot and breaking up spark, when the engine warms up.

Few months late to that party...

[BlackZenkiS14]

Still haven't figured this out yet, wondering if anyone else has any input. Car struggled at track day yesterday, frustrating the fuck out of me.

[cotbu]

So what did the jwt techs say?
Did they at least send you a new tune to test out?

[BlackZenkiS14]

So what did the jwt techs say?
Did they at least send you a new tune to test out?

Yea, they did, they sent a new tune to install, and it didn't really make a difference, car runs a bit better I guess, but didn't change this issue at all. :/

From all the logs I've sent them, they really weren't able to identify any problems in the setup at all...

[cotbu]

So really there's nothing wrong and you're so ashamed that your 240 runs perfect and makes good power, when everyone else's runs like crap, You just want to fit in somewhere ,but the you're doing it wrong! thread won't except you! Oh what to do! ;)
J/k

But seriously, it must be something simple, I'm sure you'll get it sorted out! G/l

Sent from a Highly Tuned Note 4.5!!!

[spooled240]

Could it be possible that you have an intermittent head gasket leak that's fouling out the plugs? When the car is fully warmed up and the coolant system is pressurized it might start leaking into the combustion chamber.

[Kingtal0n]

i Hope I said it already (didnt check) but I suggest going back 100% oem and start from there.

[BlackZenkiS14]

Could it be possible that you have an intermittent head gasket leak that's fouling out the plugs? When the car is fully warmed up and the coolant system is pressurized it might start leaking into the combustion chamber.

Nah, a head gasket leak wouldnt make 420whp on pump gas :naughty:

[ultimateirving]

Your plugs are bkr7e, copper I presume? Have you tried iridium or platinum ? I couldn't get my ls coil packs to fire correctly with coppers. But she ran beautifully when I switched(gotta double check if it is platinum or iridium in there now.)

[BlackZenkiS14]

Your plugs are bkr7e, copper I presume? Have you tried iridium or platinum ? I couldn't get my ls coil packs to fire correctly with coppers. But she ran beautifully when I switched(gotta double check if it is platinum or iridium in there now.)

I ran coppers for last season, but switched to the old trusty BKR7EIX Iridiums this year. Same exact issue.

[KiLLeR2001]

Have you checked voltage and resistance on the TPS sensor when it has warmed up? I've had issues before with a TPS that, once hot it would have dead spots along the range that would cause hesitation like this. So what I would do first is test resistance by unplugging the tps sensor and probing the appropriate terminals and slowly open the throttle chamber to see if the numbers climb up / down in a linear pattern.

Resistance range is 2 kOhm closed throttle to 10 kOhm WOT.

[cotbu]

Have you checked voltage and resistance on the TPS sensor when it has warmed up? I've had issues before with a TPS that, once hot it would have dead spots along the range that would cause hesitation like this. So what I would do first is test resistance by unplugging the tps sensor and probing the appropriate terminals and slowly open the throttle chamber to see if the numbers climb up / down in a linear pattern.

Resistance range is 2 kOhm closed throttle to 10 kOhm WOT.

I already suggested testing the tps, it should have given the same results, if it was failing as a lazy throttle response. Assuming he already ruled it out as that was a year ago.

Sent from a Highly Tuned Note 4.5!!!

[Kingtal0n]

The car should run pretty normal without a tps connected.

Nay a misfire. You have to think about what it means. Engine only wants 3 things; spark fuel compression. universal.

So #1 is compression test. You are sure the squeeze is there etc... Then move on to #2

Fuel. Your wideband shows good numbers, fuel pressure is there, etc... then move on to #3


SPARK. To have fuel and compression without spark occasionally, is to occasionally have a misfire. Anything from the computer to the spark plug is responsible. If you have a wiring specialty harness I strongly recommend you investigate the ECU plug, because I had a recent ignition misfire on an sr20 using their harness, and it turned out to be the ECU plug pin for a coilpack signal wasnt making a full contact, all the time.

In any case, if you cared enough you could go back to stock everything and see if the problem persist. That would narrow it down quite a bit, whether the problem did or did not still persist would provide valuable insight. A misfire is elusive, it could be a valve popping/hanging open because of a weak spring once in a while.

[cotbu]

go disconnect the tps from your sr20det, start it, oh normal now try to drive! if you don't notice a change your tps was faulty or not working. an engine running and operating are two different things.

I don't think going back to stock is an option, but if he has to by all stock sensors and harness he should just troubleshoot as much as he can before buying stock stuff.

[BlackZenkiS14]

I actually plan on trying a whole new known good TPS sensor. I know that the voltage coming out of it is correct, I've verified at the sensor, and with my Nissan Data Scan program.

[daryl337]

Does this stumble occur just after hitting the accelerator or does it continue the misfire up into the rpms afterward? Your throttle blips in vid appear to be about 500-1000 rpms worth, however if you hold this throttle does it continue to misfire as you go higher?

If it doesn't (meaning only stumbles on the initial blip) I think your throttle enrichment settings may be off on your tune.

Once the engine warms up and goes into closed loop I wonder if there is a separate throttle enrichment map on the ECU. I don't know enough about the ECU's and ROMS to say definitively - since all of my tuning is done on standalone systems.

But I really think it sounds like you are having a momentary leaning moment. You won't reflect this on a dyno or anything- because its only in effect when you first blip the throttle plate open.


Just my 2 cents.

[BlackZenkiS14]

To be honest man, I agree completely. Unfortunately I have a hard time getting ahold of JWT to have them go through the logs and tune.

Thanks for the input man!

[BlackZenkiS14]

Ok, new update:

Was having the trouble really bad today, figured out that when I unplug the TPS, it revs perfectly fine, however, with the TPS plugged in, it starts stumbling and stuttering again.

Gonna try to locate a a new known-good TPS next week to try.

[KoukiMonsta]

Ok, new update:

Was having the trouble really bad today, figured out that when I unplug the TPS, it revs perfectly fine, however, with the TPS plugged in, it starts stumbling and stuttering again.

Gonna try to locate a a new known-good TPS next week to try.


Man I hope this is the ticket.

It's been a while...without reading original posts I am assuming your TPS voltage checked out? (0.45-4.0v)?

That can be the trouble with these sensors..work fine without load but introduce heat, voltage drop, high rpms..blah blah and things can get funky.

again, fingers crossed!

[BlackZenkiS14]

Man I hope this is the ticket.

It's been a while...without reading original posts I am assuming your TPS voltage checked out? (0.45-4.0v)?

That can be the trouble with these sensors..work fine without load but introduce heat, voltage drop, high rpms..blah blah and things can get funky.

again, fingers crossed!

Yep, that's why I wrote it off so early. I voltage tested it, and datalogged it very early in the process, so I never went back to it. Really hoping this clears it up!

[BlackZenkiS14]

FUCK, FUCK, FUCK. Seriously.

Ok, replaced TPS with brand new OEM ($90) TPS sensor. Resting voltage is .44V, WOT is 4.02V, has smooth steady voltage curve as throttle increases....SAME EXACT FUCKING PROBLEM. No difference at all.

However, with the TPS unplugged, it runs much smoother, way better.

Plugged in the NissanDataScan ConsultPort to watch voltage, noticed that the voltage displayed when TPS is unplugged is 5.1V. Car revs much smoother. IDK WTF!!

Any help from here?

[inopsey]

what wiring harness are you using? oem or wiring specialties

[KiLLeR2001]

Make sure you are doing your tests when the car is fully cool and when its fully warmed up. See how the numbers fluctuate when its plugged in and when its not plugged in.

So you'll have 4 tests to conduct:

Test 1: Cool plugged in values (voltage).
Test 2: Cool not plugged in values (resistance).
Test 3: Warmed up plugged in values (voltage).
Test 4: Warmed up not plugged in values (resistance).

For values, with harness plugged in to the TPS sensor, 1. fully closed voltage and 2. WOT voltage. With harness unplugged from TPS sensor, check 1. resistance in kOhms fully closed throttle and 2. resistance in kOhms in WOT. Also be sure to check the curve all the way through the range on all 4 tests.

Report back.

[BlackZenkiS14]

what wiring harness are you using? oem or wiring specialties

OEM, and the harness has been fine in the past for 3 years of driving, then I rebuilt engine and this problem developed.

[cotbu]

FUCK, FUCK, FUCK. Seriously.

Ok, replaced TPS with brand new OEM ($90) TPS sensor. Resting voltage is .44V, WOT is 4.02V, has smooth steady voltage curve as throttle increases....SAME EXACT FUCKING PROBLEM. No difference at all.

However, with the TPS unplugged, it runs much smoother, way better.

Plugged in the NissanDataScan ConsultPort to watch voltage, noticed that the voltage displayed when TPS is unplugged is 5.1V. Car revs much smoother. IDK WTF!!

Any help from here?
The voltage with tps unplugged is normal and says to the ecu you are at full throttle, this leads me to believe you have a fuel delivery problem and maybe timing. Does the wideband read richer with the tps unplugged?
With the throttle(pedal) all you really control is air flow the ecu controls the rest. Try clearing ltft and stft.
ps $90 for a tps is rape!

[BlackZenkiS14]

Try clearing ltft and stft.

What does this mean?

And yea, it was $75+shipping. :(

I'm going to test continuity tonight with the wires and make sure the plug is functioning normally.

[BlackZenkiS14]

Checked wiring at TPS plug:

Here is what I get:

Black= continuity with ground, no voltage
White= 1.8-2.1V, no continuity with ground
Red/Green = 5.1-5.2V, no continuity with ground

[cotbu]

LTFT and STFT long term and short term fuel trims. you can clear them with nds, and nistune.
Those values look good for tps disconnected, iirc. I think its something else.
wide band reading?

[BlackZenkiS14]

LTFT and STFT long term and short term fuel trims. you can clear them with nds, and nistune.
Those values look good for tps disconnected, iirc. I think its something else.
wide band reading?

How do I clear those with NDS? I've only used that program a bit, and only a for data watching and a few of the active tests.

I'll report back with wideband info tomorrow, just idling with plugged in and unplugged?

What about my 2.1V at the plug without being plugged into TPS? Shouldnt the white wire show 0v? as its just the signal return wire?

[cotbu]

clear self learn, i use to have sequence for nds, clear self learn the set or check base idle and timing.
The voltage is correct, and i may have said its wide open throttle, but its actually part or half throttle with tps disconnected, that why i think its fuel and or timing because you said it runs much smoother, way better.

[BlackZenkiS14]

AFR is 14.7-15.1 at idle, with or without the TPS plugged in. No Change.

[cotbu]

Was hoping it was a little richer. clear the ltft and stft. The ecu may have stored all that data and you might not get a change.

[inopsey]

are you able to read the voltage of the tps with the ecu, on a laptop? is it always the same value when the throttle is closed or does it change when the car gets hot

[BlackZenkiS14]

are you able to read the voltage of the tps with the ecu, on a laptop? is it always the same value when the throttle is closed or does it change when the car gets hot

Yep, using Nissan DataScan program. Its the same hot and cold.

[BlackZenkiS14]

Was hoping it was a little richer. clear the ltft and stft. The ecu may have stored all that data and you might not get a change.

I'll have to look into how to do that, and try it this weekend.

[BlackZenkiS14]

I did the following test and got weird results, dont know what to make of them.

I was chasing down that 2.1V at the white wire on the TPS plug, apparently due to a system in the ECU, that should be reading 5.1V with the TPS unplugged. So I cut the wire on the back of harness about 5" away from plug to test voltage. With the wire cut, at the wire I got 1.3V sometimes, 2.4V sometimes, and 3.1V sometimes, and everywhere inbetween, at the TPS plug I got 0V (obviously). However, when I reconnected the white wires, I got 4.7V at the wire intersection, and 2.1V at the TPS plug. I have no idea what any of that means.

1.3-3.1V at wire; 0V at plug
http://i228.photobucket.com/albums/ee147/KyleCrangle/20150916_220612_zpsyapxvbes.jpg

4.7V at wire intersection, 2.1V at plug.
http://i228.photobucket.com/albums/ee147/KyleCrangle/20150916_220521_zpscsvuc2zm.jpg

[cotbu]

the white signal wires voltage should go up gradually to 4.~v and stop, the wire wth 5v is the ecu reference the other is ground
you need to clear self learn.

[BlackZenkiS14]

the white signal wires voltage should go up gradually to 4.~v and stop, the wire wth 5v is the ecu reference the other is ground
you need to clear self learn.

There is a loop mode in the ECU that auto sends 5v through the white wire if the TPS is unplugged, this is the problem that I was testing, and couldnt get a conclusive answer

[cotbu]

Check the mafs voltage, plugged and unplugged see if the results are different

Sent from a Highly Tuned Note 4.5!!!

[ultimateirving]

There is a loop mode in the ECU that auto sends 5v through the white wire if the TPS is unplugged, this is the problem that I was testing, and couldnt get a conclusive answer

Maybe a resistor failing? Causing fluctuating voltage. I'm no electrical engineer so maybe someone with more expertise can chime in. But that is odd if it should be a steady ~5v

[BlackZenkiS14]

Ok, so I unpinned the wire from the ECU harness, to completely eliminate the wiring, and at the prong on the ecu, with the wire removed, it read 4.1V, when I put everything back together, I got 4.1v at the wire, then eventually the tps plug. So that all seems normal. I also used a different ground for my meter on all these tests because I don't think the original ground I was using was clean enough.

However with all of this put back together, the car still shows the exact same problem. Totally fine when cold, but once reaching operating temp, stumbles and stutters. However, when I disconnect the white tps wire at the intersection I made, the problem goes away. It runs much smoother with the tps wire cut, and the engine does what it's supposed to.

I also then cut the wire a few inches behind the tps plug, and ran a fresh wire straight from the ecu to the tps sensor, to rule out any breaks in the wire within the harness. Did not fix anything.

There has got to be something inside the ecu that relates to tps signal that is causing this problem. It's the only thing possibly left.

[cotbu]

clear self learn

[Kingtal0n]

There has got to be something inside the ecu that relates to tps signal that is causing this problem. It's the only thing possibly left.

When idle speed > desired idle speed, ecu will pull timing when the tps is plugged in

perhaps watch your timing at the crank when you unplug the TPS to notice if there is a marked difference

Thats about the only thing a TPS is/should be doing at idle anyways, unless its signal wire is crossed with another random wire somewhere along it's length

[BlackZenkiS14]

clear self learn

Man, I am still confused about what you are talking about. I know we've been through it, but I would love to give it a try. Can you walk me through how to do it?

I'm not familiar with this program at all yet. And I dont think that I can change or save anything on my ECU at all...right?

[cotbu]

What version do you have?

Sent from a Highly Tuned Note 4.5!!!

[BlackZenkiS14]

What version do you have?

Sent from a Highly Tuned Note 4.5!!!

The most basic version, NDS 1. It looks like I might have a button in the functions that says, Clear Self Learn?

And what exactly does that do?

[cotbu]

it clears ltft and stft it should also clear stored voltages and return data. so it would be wise to set tps to .45v, iacv to 50%, timing at 15*btdc, base idle 850rpm.and fuel pressure to 3bar. i shouldn't have assumed your engine was setup properly, but i do think you know how to do it. i would also wait till operating temp, and when you're able to drive

these aren't magical terms or really secrets, but if you look them up and its something you don't want to do, don't do it. g/l

[BlackZenkiS14]

it clears ltft and stft it should also clear stored voltages and return data. so it would be wise to set tps to .45v, iacv to 50%, timing at 15*btdc, base idle 850rpm.and fuel pressure to 3bar. i shouldn't have assumed your engine was setup properly, but i do think you know how to do it. i would also wait till operating temp, and when you're able to drive

these aren't magical terms or really secrets, but if you look them up and its something you don't want to do, don't do it. g/l

Yea, thats the exact spec my engine is set up to currently. I'll have to do some looking into and see what that will do.

Is this anything permanent or whats risk with this?

[cotbu]

No, the voltages relearning should be immediate, the long and short term trims are just that. They require new data. So if the 02sensor is working correctly everything should be fine. You could be lean or rich if the tune is on point you shouldn't have any problems. Have you ever seen a person keep getting the same code over and over even after replacing a part? it's because the ecu learns the faulty data, it will take multiple trips for the ecu to relearn as long as there is no huge fluctuations from the old data. Clearing self learn just speeds up the process, and says relearn now.

You don't want to have leaking injectors , a faulty mafs, a bad 02sensor or even fouled spark plugs
Most people see an increase in fuel economy, clearing self learn. Others will notice correct mafs voltage other will notice they can idle now at a decent rpm. If there is no change the problem is obviously still there, you just have to find it. You just might be able to see it so logging with nds is a good thing to do if you choose to clear self learn.

Sent from a Highly Tuned Note 4.5!!!

[BlackZenkiS14]

Well, fuck my life.

I just picked up an Enthalpy Tuned ECU with similar spec (same injector and maf at least), and it still does the exact same god damned thing. I'm seriously at a loss. I have no idea what to do at this point.

Is there any correlation between the ECU reading the TPS and the car warming up?

What things with temperature added could cause them to malfunction? I had ruled out actual temperature being the problem (as opposed to temperature that the ECU is reading), because it happened so perfectly with it reaching operating temp. I guess it does get worse slightly when its really hot outside compared to cool outside. But what the fucking fuck.

[jr_ss]

Have we discussed grounds on the motor? This has been going on for so long now I can't remember. Have you updated the OP?

Anyway, how many do you have? Try adding a few. 4ga wire from the block to a clean unpainted spot on the frame rail. Maybe one from the head to the bulkhead as well.

[BlackZenkiS14]

Yep, I have 3 additional engine ground on engine, 4ga. I confirmed continuity from all parts of block and head to chassis ground just last week.

Tried unplugging knock sensor, makes no difference.

[BlackZenkiS14]

Ok, did some more testing tonight.

Tested a known good knock sensor and sub harness...problem persisted.

Tested a known good set of OEM SR coil packs and sub harness, no change in problem.


I did play with the fuel pressure a little bit and paid close attention to it. When priming the fuel system (KOEO), the gauge seemed to pulse rapidly around 40-45psi. Then once the fuel pump turned off, the pressure dropped immediately to 0psi. That seems odd to me. Any ideas?

With engine running, vac line connected, its at 40psi.

Also, we increased base pressure to 65psi, and the problem seemed more prevelant and heavy. Then we dropped to 20psi base, and the problem seemed to diminish a bit, and the engine didnt seem to load up as badly. Ideas?

[daryl337]

Nevermind.

Was hoping you had top feed injectors - a pulsating fuel pressure could be indicative of a rail pulse, so a pulse dampener can help. However that should not be a temperature specific concern. Its very strange that this concern is only happening to you when the car warms up. That tells me you have either an issue on the open loop side of the tune, or possibly a voltage drop issue (however I see you have a mechanical fan so I don't think it is that) You said that the other ECU had a tune for the same injector - are you *sure* it is for that specific brand of injector? Or just similar CC's? The base injection times on the tune might be correct but if they are different brand of injectors you could very well be experiencing an issue with injector dead time.

An increase of base pressure to 65 would certainly cause a lagging issue because you are altering your injection amount significantly. I'd bring it back to proper psi so you don't add more problems. Your fuel pressure should not be fluxuating 5 lbs during priming. Does it fluxuate while running? If so, disconnect the vacuum line and test it again to see if it is fluxuating while disconnected and engine running. If it does not fluxuate anymore then you have either an issue with your vacuum diaphragm in your FPR, or you have a vacuum issue with your engine still - possibly mechanical. Your vacuum gauge in car seems fairly responsive, it should indicate a pulsing vacuum signal if that were the case. I'd think it is safe to rule out a mechanical vacuum issue, so look at that fpr.


If it still fluxuates after the vacuum line was disconnected, you gotta look into your fuel system some more. Check for leaks, check that FPR, and pump.


Best of luck to ya.

[BlackZenkiS14]

Ok, heres the update for now. Replaced my AFPR with a known good Aeromotive AFPR, and it didnt make a noticeable difference in the issue I am having, however, it did hold positive pressure after the FP turns off like it should, so I'm going to replace it anyways.

We also pulled the rail to watch injectors on fuel pump priming, dry as a bone, not a leak.

Also, I decided tonight that it is an actual temperature problem, even after the car reached OT, the problem wasnt present (weather is currently in the 50's here, so much cooler than previous testing). It took a run around the block to start hesitating like normal. So its gotta be something actually warming up, and causing malfunction.

I hooked up my NDS again to start playing with some active tests, and this time I pulled up diagnostics, and came up with Code 12 and 34...? Now, all of these tests were done on the Borrowed 62 Enthalpy ECU, not my ECU. So the o2 sensor isnt reading.

Codes...where can we trace with these? I've tried a known good MAF and a known good Knock sensor with sub harness...
http://i228.photobucket.com/albums/ee147/KyleCrangle/Diagnostic%20Codes_zpssshp8y3a.jpg (http://s228.photobucket.com/user/KyleCrangle/media/Diagnostic%20Codes_zpssshp8y3a.jpg.html)

Also, here is the display with engine cold, KOEO.
http://i228.photobucket.com/albums/ee147/KyleCrangle/KOEO%20Cold_zpspn03uycg.jpg (http://s228.photobucket.com/user/KyleCrangle/media/KOEO%20Cold_zpspn03uycg.jpg.html)

Here is display with Engine on, cold.
http://i228.photobucket.com/albums/ee147/KyleCrangle/Engine%20On%20Cold_zpsp2n1rimz.jpg (http://s228.photobucket.com/user/KyleCrangle/media/Engine%20On%20Cold_zpsp2n1rimz.jpg.html)

Here is display with Engine on, Warm.
http://i228.photobucket.com/albums/ee147/KyleCrangle/Engine%20On%20Warm%20after%20active%20tests_zpsolp vjcvv.jpg (http://s228.photobucket.com/user/KyleCrangle/media/Engine%20On%20Warm%20after%20active%20tests_zpsolp vjcvv.jpg.html)

[cbeuglas]

The knock should read 2.5v out and can retard timing when warm.

Sent from my SAMSUNG-SM-G920A using Tapatalk

[cbeuglas]

Also if you still have knock and MAF codes after replacing with a known good ones the check your harness.

Sent from my SAMSUNG-SM-G920A using Tapatalk

[BlackZenkiS14]

(also, I should note that the 34 code could have come from the testing I was doing with the knock sensor in days past, running car with unplugged, ungrounded, shielded in a rag not connected, etc...I didnt clear ECU after doing these tests)

[cbeuglas]

Clear and retest

Sent from my SAMSUNG-SM-G920A using Tapatalk

[ultimateirving]

You can try using a resistor, wire it in and used to fool the knock sensor, IF it keeps giving you issues.
Also I know some ecus can turn off the knock sensor input as well.

[BlackZenkiS14]

You can try using a resistor, wire it in and used to fool the knock sensor, IF it keeps giving you issues.
Also I know some ecus can turn off the knock sensor input as well.

Do you have a link or how-to on the info regarding the resistor in the knock sensor?

[ultimateirving]

Do you have a link or how-to on the info regarding the resistor in the knock sensor?

I'll check around on google for you. I did it a long time again because I thought I was having issues with my knock sensor.


After a little digging around I found this.
http://zhome.com/ZCMnL/PICS/detonationSensor/detonationSensor.html
Same concept just a different Nissan.

[ultimateirving]

The knock should read 2.5v out and can retard timing when warm.

Sent from my SAMSUNG-SM-G920A using Tapatalk

I thought this number should be closer to 3.3v when reading normal.

[BlackZenkiS14]

Thanks man, I might give that a try!

[cbeuglas]

Z1 motor sports sells a knock sensor delete

https://www.z1motorsports.com/oxygen-and-knock-sensors/z1-motorsports/knock-sensor-bypass-plug-p-5580.html

Sent from my SAMSUNG-SM-G920A using Tapatalk

[cbeuglas]

I made mine using a 1 mega ohm resistor cut and soldered into my factory line using the knock sensor harness.

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[cbeuglas]

I will say this even with the knock sensor issue I never had the issue you are having. It was just sluggish and poor gas mileage. But that being said fix what you know is an issue first as it could be a domino effect.

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[BlackZenkiS14]

Thanks man, that might actually work!

[Javi802]

have you compression tested the engine?

[BlackZenkiS14]

have you compression tested the engine?

Nope, but I have no reason to assume that compression is bad. Although I plan on testing this this week.

[Javi802]

Get any closer to figuring out what the problem is/may be?


And have you taken it to any local 240 "specialists" in your area? If there are any, that is

[BlackZenkiS14]

Get any closer to figuring out what the problem is/may be?


And have you taken it to any local 240 "specialists" in your area? If there are any, that is

lol I am the specialist, and my best friend owns the largest/best race shop/fab shop/swap shop in the midwest lol

Here is what I've done most recently:

I rewelded my wastegate dump pipe, which at some point broke off this past few weeks...no fucking idea.

I also replaced my bad fuel pressure regulator, so I know that will affect it a bit, hopefully positively.

I also found a 95% broken wire (1 weak strand left, sorta) in the MAF wiring at the plug, so I resoldered a fresh wire into the pin, and re-pinned the connector. It was too late in my subdivision to fire up the car with neighbors close by, but I'll give it a test tomorrow.

Well, looks like it either didnt make a difference, or made a marginal difference. I dont think it was warm enough to get it to start really choking like it normally does. But it was smoother today after fixing those things. I'll have to get it out for a drive to confirm though.

I'm going to do a full run of tests on continuity and voltage of the MAF wiring next week probably.

I also get my actual own JWT ECU back tomorrow, so thats when I'll really start chasing down stuff again, watching NDS, etc...

I've already tried a couple different known-good Z32 MAF's, didnt make a difference.

Now, on the TPS thing, when you unplug TPS, it sends ECU into some kind of fail safe mode where it only uses certain sensors, and ignores others, and it changes timing. I gotta figure out what that correlation is, cause thats where my answer is.

[BlackZenkiS14]

I'm getting to the point now that it has to be something in the wiring, and I'm getting close to just buying a Wiring Specialties Pro harness....

[Kingtal0n]

Whelp, I just installed some HKS cams into my sr20det and now it also has a stutter and miss at idle. You sure you arn't just having large camshafts? ^ ^

[BlackZenkiS14]

Whelp, I just installed some HKS cams into my sr20det and now it also has a stutter and miss at idle. You sure you arn't just having large camshafts? ^ ^

Mine aren't bad, just JWT S3 cams...260s IIRC

Is yours doing the exact same thing as mine?

[Kingtal0n]

Mine aren't bad, just JWT S3 cams...260s IIRC

Is yours doing the exact same thing as mine?

Nah, I've tuned a few sr20det with S3 JWT. They are super mild and low-key, wont cause it to run poorly at idle unless its really lean, like 16.5:1.

[BlackZenkiS14]

Yea, I wouldnt have expected my cams to cause issue.

[Kingtal0n]

Yea, I wouldnt have expected my cams to cause issue.

You dont have adj gears do you? If they were adjusted slightly off it could possibly give a more choppy idle. Come to think of it, my HKS cams have WAY more chop when my VTC is enabled. I never tried a set of S3 JWT cams on an S14 motor.

In any case, a miss is way different than a lope. A an idle "lope" has a distinct way of causing the engine to miss, in that it is random, your at 910rpm this second, the next you are at 840rpm, and them possibly back up or down more or less, depends on how the engine feels. It is a reliable, consistent, bouncing up and down of engine rpm more or less. I would know it right away when I hear/feel it.

[BlackZenkiS14]

I have stock cam gears, and an S13 motor. And the actual idle is fine, has a nice lope to it.

[Kingtal0n]

I have stock cam gears, and an S13 motor. And the actual idle is fine, has a nice lope to it.

That worries me. The S3 cams I've installed in the past make no noticeable lope. Furthermore, if you are saying there is a lope, how can you know that this is not the cause of your missfire? When in fact that is partially what makes a lope erratic/ anticipated.

at this point I would say maybe you have some really old grind of S3 that is different from the new S3, or perhaps, you have something larger without realizing it. Did you ever check the Part# on your cams?

[BlackZenkiS14]

Yep, confirmed with JWT, its definitely an older style S3, prior to the HL availability.

[BlackZenkiS14]

Alright, starting down a new road here a little bit.

Help out:

http://zilvia.net/f/showthread.php?t=615034


Hey guys, I'm trying to track down some problems with my car, and I need some comparisons, I feel like my car isnt pulling enough vacuum at idle.

I have a built S13 blacktop with S3 cams. and I get 350 mm/hg at idle. How about you guys?

http://i228.photobucket.com/albums/ee147/KyleCrangle/20151014_164055_zpsgx2y8ixg.jpg

[daryl337]

13 is a little low, but it isn't absolutely terrible.
Mine runs in that ballpark, however I am running 270's not 260's.

Do you have adj. Cam gears? If so, you can try to adjust cam timing.

It could also be in the tune.... an overly rich engine tends to have a lower vacuum.

your best bet is if you perform a leakdown (make a tester out of 2 gauges, some brass fittings, with a .040" restrictor in between the gauges). Set an air compressor's regulator to 100 psi and then screw that bad boy into the spark plug hole of a cylinder that is at TDC.

Read the pressure drop from gauge 1 to gauge 2 and there ya go... leakdown. A nice bonus is you get to hear where the air is leaking to help you diag.