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

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-Kyle

jr_ss

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

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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?

__________________
-Kyle

BlackZenkiS14

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

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-Kyle

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

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-Kyle

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.

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BlackZenkiS14

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

__________________
-Kyle

jr_ss

How many grounds do you have?

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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.

__________________
-Kyle

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.

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ultimateirving

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

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BlackZenkiS14

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.

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-Kyle

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.

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BlackZenkiS14

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

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-Kyle

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

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-Kyle

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.

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.

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-Kyle

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

Cough, cough...

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steve shadows

Definitely sounds like ignition /thread

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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

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...

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-Kyle

1990 sr hatch

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

BlackZenkiS14

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.

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-Kyle

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

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.

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