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.



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?

[240silvia]

Originally Posted by 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?

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]

Originally Posted by 240silvia

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.

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?

[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 -

[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

[8_6_Fo_Life]

Originally Posted by 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.

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 -

[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)

[8_6_Fo_Life]

Originally Posted by duey

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 -

[duey]

Originally Posted by 8_6_Fo_Life

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 -

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

[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.

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.

[8_6_Fo_Life]

Originally Posted by 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.

Thank you very much.

[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.

[8_6_Fo_Life]

Originally Posted by mrmephistopheles

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 -

[mrmephistopheles]

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

[Ghettokracker71]

Hey 8_6 I pmed you.

[8_6_Fo_Life]

Originally Posted by Ghettokracker71

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 -

[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.