Weak SR? (dyno chart)

[Mike22bSTi]

Hi all, hate to have my first post be a beg for help but my SR is not up to snuff.

http://img.photobucket.com/albums/v385/mike22b/mike2.jpg

here's a quick list of the pertinent mods... it's a red top with a Koyo radiator, HKS SS BOV (open air), Walbro 255 fuel pump, greddy fmic. I understand that an sr with these mods should make at least 185... and mine obviously is not.

I've searched this pretty exhaustively and have run out of ideas, the timing is at 15* the tps is set correctly, i could not find a boost leak to the best of my ability, which was my leading suspicion. I'm at a loss.... my only other theory is that it was never at operating temp, i think the koyo works a little to well and keeps it below temp. A temp gauge is in the mail which should shed light, but for now the thermostat on my elec fan is set to run at 170* and during the runs the fan never came on, but i'm not sure how reliable that thermostat is. So.... i don't know. Any suggestions, other theories? Thanks a lot!

[mrmephistopheles]

your only performance 'mod' is a FMIC.
If you're still on stock intake and exhaust, those numbers aren't terribly atypical. Maybe a bit on the low side, but not too low. Do you have a boost gauge to insure you're boosting at stock level (.5 bar / 7psi)?

Hmm on second hand.. they are kinda low.. have you performed a compression or leakdown test on that motor?

[twisted_240]

well those mods u listed only the fmic would do anythign for increase in power.
so id imagine u'd be at close to stock hp rating.
mostly your mods keep the engine cool and the bov makes it run rich on shifts and when u let off the throttle.
you look for an exhaust leak? compression test? slipping clutch? any other mods other than whats listed? u running any sort of exhaust or you using stock?

edit: damned it too slow,. ill leave what i typed anyways haha

[8_6_Fo_Life]

To further this thread...

He is running a stock intake and stock exhaust beyond a 3" downpipe. After that it flows through ALL stock exhaust, even the tiny tailpipes. My thought was that the exhaust was a HUGE restricting factor of his HP, so we disconnected the exhaust at the downpipe for a final run and only netted a 10hp gain. So, that didnt make him, nor me happy.

The clutch is a brand new and is not slipping. Its whatever heavy duty unit everyone and their brother is using. No issues.

The boost gauge reads 7psi clearly and holds it fine. It has no problems reaching or holding full boost throughout the entire run.

We have not yet performed a compression test or a leak down test.

BTW, since it wasnt noted in the first post and it DOES make a differnece...these numbers are from a DynoJet 224x.

8_6 fo' life - :fruit:

[Jeff240sx]

I'd also look into timing. I don't know what sr motors run, but there are a few reasons for the lumpyness of the curve, and timing is one of them. Or ignition, as in fouled plugs, ect. Was the car breaking up on the dyno? Bad gas?
One other thing I'm fairly worried about are your a/fs. They're very lean up to 4400 rpm. Very lean. Then it gets better, and finally a bit rich, which is all good for that boost and rpm. Cars generally like 12.5:1.
Then again.. what the hell am I? An armchair dyno specialist?
-Jeff

[240Driver39]

yeah..id say compression test...my bone stock ka nearly pulled those kind of numbers....while my friends ka with intake/exhaust DID pull those numbers....

[duey]

somethings definately up with your motor. Only thing i have different than you is ; stock radiator, n1 dual, gutted cat, and greddy turbo extension. And i made 217rwhp and 204tq at 7psi, i'd definately check your compression. The dyno i ran on was also a Dynojet 224x so we're both running on the same type of dyno.

Here's my dyno chart for comparison (everything else above 217hp is with the boost turned up)
http://memimage.cardomain.com/member_images/8/web/296000-296999/296453_114_full.jpg

[8_6_Fo_Life]

I'd also look into timing. I don't know what sr motors run, but there are a few reasons for the lumpyness of the curve, and timing is one of them.

That is quite true. Normally on dyno graphs, those wiggles and jumps usually translates that the car wants MORE timing. But, just yesterday we checked the timing on his car and it was on dead-nuts 15*. Personally I dont know enough about the SR20DET to reccommend any more timing then that, even on stock boost.

Or ignition, as in fouled plugs, ect. Was the car breaking up on the dyno? Bad gas?

There could be some sort of ignition problem, but I doubt it. It has never broken up on the street, nor on the dyno. The car never stumbles or misses...its just weak. There is no guarantee, but I dont believe he had bad gas. There was NO pinging present, and it has never pinged before.

One other thing I'm fairly worried about are your a/fs. They're very lean up to 4400 rpm. Very lean.

This was concerning us as well. The car is making full boost I would say around 3000rpms if not sooner. I would like to see the car pegged at the 12.5-12.8:1 line from there to redline, but as you can see it stays lean until 4,400 for some reason. Its running a stock SR computer, nothing else (no piggy back/afc). I would have to assume that with stock boost levels and practically no go-fast bolt ons it should be plenty to have the car running right. I am almost leaning towards a bad stock fuel pressure regulator. In the past I have seen a few cars on the dyno with bad FPR's create a similar A/F reading. Thoughts?

Then again.. what the hell am I? An armchair dyno specialist?
-Jeff

Ha, Mike and I appreciate the help...we need it. Plus I am a dyno specialist, so I need to learn how to tune SR's for the future. This one has me stumped.

8_6_Fo_Life - :fruit:

[8_6_Fo_Life]

Here's my dyno chart for comparison (everything else above 217hp is with the boost turned up)


Those are very nice numbers! What kinda boost are you cranking it to for the 260hp/276ft.lbs run? And to run that boost what else did you have to add? Running a AFC or just a Adj. fpr? Or just cranking the boost and lettin her eat?

8_6_Fo_Life - :fruit:

[duey]

Those are very nice numbers! What kinda boost are you cranking it to for the 260hp/276ft.lbs run? And to run that boost what else did you have to add? Running a AFC or just a Adj. fpr? Or just cranking the boost and lettin her eat?

8_6_Fo_Life - :fruit:


260 is w/14.5psi, no afc or adj fpr just an mbc cranked up and hoping for the best :x: :rawk:

[8_6_Fo_Life]

good times. That has been my idea from the start for Mike22bSTi's car, but he wont man up and go for the glory.

Maybe its because if I blow it up I dont have to pay for it...hmmmm. :rolleyes:

Do you happen to have a a/f print out of your stock and 14.5psi runs? That would help me out a bunch.

ps - I love your car. Nicely done.

[duey]

i'll have my a/f print out by tomorrow since i'm running on the dyno again in a few hours. i'll make sure you get my chart for reference.

[mrmephistopheles]

I say check the basics. MAF ok? TPS set right? No idle issues? No boost leaks? BOV not leaking? Engine grounds all good? Plugs clean and properly gapped? Coilpacks securely mounted? Turbine not blown? blahblahblah.
Do a compression test before all of this to make sure you're getting good numbers first.
If the numbers are doo, you'll know the problem before you start troubleshoosting.

[Dream240]

I have a question. I've been doing alot of reading lately on turbo applications, Supras, 300zx, WRXs, etc. and the one thing I've found in most of these cases on the dyno they pulled low numbers in the beginning, then reset the ecu, and voila!! The reset ecu was to remap the timing, fuel etc. and the power was back up to where it was supposed to be.

My question is this, could this be a common problem in SR20s that gets easily overlooked? I'm still elarning aobut turbos so that's why I'm asking. Or maybe he's got the wrong ecu in there causing the whole engine to run poorly? Dunno just a speculation.

[mrmephistopheles]

it's a possibility (along with the possiblity of the ECU being in diagnostic mode), but the numbers hsouldn't be THIS bad.

[8_6_Fo_Life]

i'll have my a/f print out by tomorrow since i'm running on the dyno again in a few hours. i'll make sure you get my chart for reference.


Thank you very much.

[Ghettokracker71]

Hey 8_6 I pmed you.

[8_6_Fo_Life]

I say check the basics. MAF ok?

We havent checked this yet. He'll get on it.

TPS set right?

We checked this when we checked the timing. TPS is .50v @ idle and 4.01v at WOT, key on, engine off.

No idle issues?

None.

No boost leaks?

Not that we can find. We did the soapy water check, but I am now thinking we need to redo it with some carb cleaner or something that will truly show a vac. leak in the system.

BOV not leaking?

Same as above, gotta recheck with carb cleaner.


Engine grounds all good?

From what I can tell, yes. But everything will be double checked.

Plugs clean and properly gapped?

Plugs have not been checked yet. I asked early: What is the plug of choice for a stock SR. What is the gap of choice?

Coilpacks securely mounted?

Yes.

Turbine not blown?

No, nothing that severe. The turbo is in great shape.

Do a compression test before all of this to make sure you're getting good numbers first. If the numbers are doo, you'll know the problem before you start troubleshoosting.

We'll do a compression check pronto. Thanks again for your time with this.

8_6_Fo_Life - :fruit:

[8_6_Fo_Life]

Hey 8_6 I pmed you.

...and I replied.

[fliprayzin240sx]

I run NGK spark plugs gap em at 28.

[Jeff240sx]

A buddy (who IS a dyno specialist) say check the turbines. Shaft play, chewed up blades, spins freely, ect. Or compression.
-Jeff

[8_6_Fo_Life]

Will do. Thanks again!

8_6_Fo_Life - :fruit:

[Mike22bSTi]

Thanks guys for the responses and thanks 8_6_fo_life for filling in the details while i am away.

Like he said we'll have to do a compression check and a more extensive boost leak check, Also make sure my plugs are up to it.

What caught my attention was the MAF. It is still the origional one from the KA, which had 300k miles on it... i had assumed it was alright but now i am suspect. A faulty MAF could explain my fuel ratio situation. Is there a way to test it's condition with a voltmeter, or just the ground?

And Duey your car is both powerfull and beautiful, I'm most jealous.

Thanks again!

[Ghettokracker71]

300K on it? WTF??? Holy shit replace that thing right now. RIGHT NOW.

[TheSnail]

Damn thats low. My almost stock Ka with no cat, cat back exh, intake, electic fans, lightend crank pully, dynoed 149.4whp and 147.9wtq, looking at the dyno sheet right now. That means that sr is sitting at 180ish hp to the crank, which is 25hp lower then a bone stock one.

[8_6_Fo_Life]

Yea, car had 313k on it. I think it was a KA Diesel.

[Mike22bSTi]

well, 300k asuming it hasn't been replaced before.

What is the preffered MAF upgrade? Is there any difference between the single cam and twin cam MAF. I've heard a Cobra MAF is best for 400+ hp configuration but i don't think i'll be needing something that extensive.

[kazuo]

DOHC MAF won't work on the SR20. Only the SOHC (Which is the same as the stock SR20 piece).

Z32 MAFS will need a reflash or a AFC. Cobra MAF will need a reflash.

You're about 20HP short there given that you dont have intake/exhaust mods. With intake exhaust at stock boost you should be at 180HP or so (see also: Nadine's dyno in Import Ricer, Coleman's SCC dyno, my own dyno & my friend's dyno)

Stock no mods = 160
Stock w/ I/E = 180

Roughly. I am speaking DynoJet numbers BTW.

Good luck man

[Ghettokracker71]

As cheap as you can get the SOHC MAF's,I'd go ahead and replace it with a lower milage one. Goddamn,300k *shakes head*

[8_6_Fo_Life]

Stock no mods = 160
Stock w/ I/E = 180


He put down 159hp 166ft.lbs with open 3" downpipe :-/

8_6 - :fruit:

[Jeff240sx]

Turbine and/or compression, as well as double check the ignition. There is a larger problem than just the breathing. If that was a Mustang dyno I wouldn't be so worried, but...
Generally MAFS problems are noticable, as in sputtering, bad idle, running rich, ect. You can test it be checking the continuity over the pins.
-Jeff

[nlzmo400r]

thats a lil better, but put the exhaust back on and check all the areforementioned possible troubles? or did u already do that?

[8_6_Fo_Life]

We only disconnected the exhaust at the downpipe for the dyno run. After seeing the small gain we buttoned it back up and he's been driving like that since.

He hasnt gotten a chance to test anything cause it has been storming here all day. Tomorrow I believe he will be changing plugs (gapping somewhere from .28-.32), checking the MAF, and checking the turbo or damage or shaftplay or anything unusual.

Thanks again to all those shooting out ideas. Zilvia.net seems alright in my book. :D

[mrmephistopheles]

I think it was a KA Diesel.

lol

Now THAT's funny.

[Bradman123]

better then 240sxforum for me so far... these types of experiences scare me. especially after what seems to be a bad luck streak for my sr..im excited to see what comes out of this.

[Dweezil]

At 300k miles I'd also check the fuel pump an make sure your getting enough fuel to start with.

[8_6_Fo_Life]

better then 240sxforum for me so far...

Other then SR20Forum.com this seems to be the best tech/Nissan forum I've found. I dont even own a 240, but I've alreay learned a great deal about my friends car with trying to get his right. I appreciate it all.


At 300k miles I'd also check the fuel pump an make sure your getting enough fuel to start with.

The car has a brand new Walbro pump...190 or 255 or whatever is normally used, cant remember. The car has great fuel psi at idle and steadily increases under boost. At times I have almost thought the car had too much fuel psi, but the a/f reading is obviously showing different.

[duey]

just to let you know i never made it to the dyno yesterday to get those a/f readings for ya. It rained so bad up here i decided not to drive the car. I will most likely get back on the dyno sometime next week, PM me or email me your email address and i'll send you my chart when i get it done.

[8_6_Fo_Life]

pm sent...thanks

[240silvia]

your only performance 'mod' is a FMIC.
If you're still on stock intake and exhaust, those numbers aren't terribly atypical. Maybe a bit on the low side, but not too low. Do you have a boost gauge to insure you're boosting at stock level (.5 bar / 7psi)?

Hmm on second hand.. they are kinda low.. have you performed a compression or leakdown test on that motor?


ookkkkkk....... I was going to post those exact words.... but.... he beat me to it! Plus if you are still on stock exhaust... that is WWAAAYYYYY restrictive! Mine is 3 1/4 off the turbo!!!!! LOL, upgrade exhaust, you will get a nice gain. Good luck bro...

[8_6_Fo_Life]

ookkkkkk....... I was going to post those exact words.... but.... he beat me to it! Plus if you are still on stock exhaust... that is WWAAAYYYYY restrictive! Mine is 3 1/4 off the turbo!!!!! LOL, upgrade exhaust, you will get a nice gain. Good luck bro...

Read the whole thread. :rolleyes:

The exhaust issue was covered many times...thats not the problem.

[Mike22bSTi]

Thanks for the help guys, unfortunately I haven't been able to perform any of the check ups and ideas you've offered and I'm going out of town tomorrow, which means it will be 5 to 6 days before I can mess with the car.

Here's a list I've compiled so far to look at:
1) Do a more thorough boost leak check
2) Inspect/replace my ancient MAF
3) Check coilpacks and plugs (properly gapped)
4) Inspect Turbo (believe it or not but after 7 months of owning the car I've never peered beyond the exhaust shield
5) compression check
6) reset ECU

As soon as I get back I'll perform all this and anything else you guys can suggest and I'll be sure to keep you informed. While I'm gone I'll still have occasional access to the web, so I'll stay in touch. Even if I can't my boy 8_6_fo_life, will take care of business. Ha! he's posted more than I have.

Thanks again

[Mike22bSTi]

Ok i'm back and i've had enough time to get some things done/looked at. Here's what i haven't had a chance to do yet and will be doing in the near future.

1) i haven't done a more thorough boost leak check
2) Inspect Turbo, easy but just haven't done this
3)compression check, will hopefully do this tomorrow along with the above

Here is what i have done

1) Inspected my MAF - looks fine, not so sure it's the original one, because it's in good shape, i didn't test continuity in the pins, i'll do that if nothing else pans out
3) Checked coilpacks and plugs (properly gapped)- i actually replaced the plugs and gapped at .032, and the old ones looked good. The coil packs and connecters were clean
4) replaced ka fuel filter with a 300zx TT unit
6) reset ECU - and i did get a code!

It flashed long once and short once, then repeated itself, which i believe is code 11, meaning CAS circuit... so that's interesting.

however i have no idea where to go from now, suggestions/thoughts?

[8_6_Fo_Life]

I drove Mike22bSTi's car today. It has a strange hesitation at tip in, any gear, and at WOT it stops pulling at about 5,000 @ 7psi. It will phsyically rev beyond and well to redline, but there is no power being made beyond 5,000 or so.

Boost builds quickly and strongly...holds steady for the most part, but it feels like its down making power by about 5k or 5500. One thing I noticed when making a hard/WOT pull in 3rd gear is that up near 6,000+ RPMs it almost looked like it was backing off 1-2 psi. I dont know if that is just the gauge reading inaccurately under load, or if the motor is truly making such less power that it makes less boost as well. Now keep in mind that he is running a 3" downpipe into stock '89 240 exhaust. Is it possible that the restrictive nature of the stock exhaust is actually building back pressure and decreasing the amount of boost in high level rpms? When we dyno'd the car with an opendown pipe it still didnt make a drastic difference, so I never noted this as a major factor. I just jammed about 30 questions into one paragraph...sorry.

He said he checked and got a Cam Angle Sensor code (11). Well, I'm not use to these types of ignition systems so does that mean the CAS is adjusted wrong, or faulty all together? It would somewhat make sense because it feels like it is either pulling timing at 5,000 or not advancing appropriately. Either way, the power is not there. BTW, timing is set @ 15*.

Any help would be appreciated, I am 99% it has to be a timing issue of sorts but I just dont know enough about this motor to start experiemting without consulting some of you guys on here first.

Thanks in advance and please excuse my 6000 questions at once.

[silverside]

get a known good CAS and retry

[Id-]

when the car falls flat on its face like that; its ignition timing!!! its not being advanced; or its being retarded for some reason

i'd guess because it was running lean; but if its throwing a code for a CAS, then i'd bet some money thats your problem since it is related to ignition advance :)
us 2jz-GE motor guys dont have a CAS :) we have a distributor ;)

[Dream240]

He said he checked and got a Cam Angle Sensor code (11). Well, I'm not use to these types of ignition systems so does that mean the CAS is adjusted wrong, or faulty all together? It would somewhat make sense because it feels like it is either pulling timing at 5,000 or not advancing appropriately. Either way, the power is not there. BTW, timing is set @ 15*.

Heh, that's what I thought. An ECU code rolling around in there. 100 bucks that's the prob. As far as the exhaust, doesn't matter for this type of power loss. Just power freed. Bigger exhaust will net more power not get the car back to normal range.

Good luck, keep us posted!

[Mike22bSTi]

thanks guys, looks like this is the problem :bite: so lets hope it pans out. I need to find another local SR owner, see if I can switch it out to confirm our suspicions.

I think I'll have to call JGY customs here in Virginia and see what they think... also see if they have any... does anyone know where one can source a CAS? I understand it's only found in SR motors and there is no USDM equivalent.

[TokyoNights]

You can usually find a used cas on ebay..also gap your plugs to .028-.030

[DuffMan]

I would be willing to bet good money, if you dynoed it with the knock sensor unplugged, you would see normal power levels.

[Mike22bSTi]

How much would you be willing to bet? say, the price of a new CAS?

why are you so confident? Do you think mine is faulty?

[Id-]

i doubt its knock thats causing the ecu to pull timing; i think its a defective CAS period; you can hear bad knock on a SR20 with a stock turbo; itsnot like a atmosphere-vent external wastegate or something

[DuffMan]

Haha, if its the CAS I'll send you mine when I go standalone.

[Mike22bSTi]

It's a deal duffman. However, a resolution for this will be delayed a bit as class starts tomorrow! And that always gets in the way of everything.

[Mike22bSTi]

I checked the ECU today again after it had been cleared and didn't get the CAS code again, just got back 55. I drove it plenty between clearing and rechecking. So who knows how long that code had been sitting, could be left over from the install if the CAS was unplugged temporarily. So i'm not so sold on this now as the solution...

[Mike22bSTi]

Ok, here is an update. I finally got around to a compression check and it came out good... abnormaly good
1- 168
2- 167
3- 168
4- 170

So, that was a releif..... Also i was able to swap my MAF with a known working one, and it didn't make any noticable difference. So 2 expensive possiblilities have been eliminated... and i'm at a loss again. But I'm nearly convinced it's a timming issue, something aint right with my timming, i just don't know what it is.

Next up is an extensive boost leak check (although i really think one would be more noticeable), Recheck timming and teh TPS and swap my coilpacks with my dad's Maxima's (how convenient!)

I also want to rule out the knock sensor, as DuffMan has suggested, however i understand the motor won't rev past 4 or 5k with it unplugged, is this so, how else would i check it?

Have i missed anything?

[Mike22bSTi]

After checking every flipping thing possible i got a chance to swap the CAS with a known good one and it made no difference, the original CAS just had a warped rotor and was rubbing against the optical sensor which would throw a code every once and a while.... On to the good stuff...

The ECU running my car is a 63 (for an automatic car), and today i swapped with a 62, And bam! runs like a champ. I had a BAD studer problem with the motor below 2.5k rpms, which actually had become a bigger issue than my powerloss because of the horrible drivability it produced. Now it's totally gone, it idles like a rock and i believe it feels stronger, however i want to get it on the dyno to know for sure so i don't get too excited.

Thank you guys for all your help, hopefully by this weekend i'll have it dyno'd, and i'll be sure to post and let you know how it all went down.

Respect!