sr20det idle problems *****not your normal easy fix though!***

[se7en_]

Ok. Here's the details.

My car was fine, so naturally I had to 'Modify' it more than it already was.

old mod list:

550 densos
z32 maf
t517z turbo
freddy intake

I added:

apexi HG and arp studs
procams and BC head package(valves, springs, retainers, 5 angle valve grind)

Now it won't idle with the maf plugged in.

Things I've checked:

boost leaks - none. holds psi.
timing - 15 degrees
TPS - 0.46v at idle
Checked maf voltages - 1V key on engine off - 1.42v at idle with 5v ref wire disconnected so it'll idle
I also double checked both grounds on the maf and they are good as well.
12V wire on maf is good too.
It idles and starts perfect, but it won't idle with the maf plugged in.

I can get it to run with maf plugged in if I fuck with the throttle.

I should add. It ran fine with this setup before the head swap.

Anyone have anything else I can check?

[ultimateirving]

Procams? I heard some where these required solid lifters. Is that a non-truth?

[se7en_]

There are two type of procams. Hydraulic and solid. I have hydraulic ones.

[Kingtal0n]

Does the engine die as if you cut the ignition suddenly? As if all the fuel is being pulled out at once?

Do you have a wideband?

Try making a boost leak on purpose to increase the maf voltage- see if that will get it to idle.

[se7en_]

No. it seams to just trail off. and I can keep it running if I feather the throttle sometimes.

I don't have a wideband. Workin on it. I'll try the boost leak to increase the maf voltage and see if that helps...what would that tell me though?

[se7en_]

bumpski bump

[steve shadows]

What EMS are you running Power FC?

Either way I can probably help you figure this out via tech support sessions remotely. Sounds like a wiring issue on the MAF if it's not a problem with the ECU / EMS setup.

Just make sure to email me because I so busy with remote tunes for various builds and drifting teams that I am rarely on Zilvia haha - I try though

[email protected] or direct message me on my fb page: https://www.facebook.com/shadowerks

Thanks

[inopsey]

What EMS are you running Power FC?

Either way I can probably help you figure this out via tech support sessions remotely. Sounds like a wiring issue on the MAF if it's not a problem with the ECU / EMS setup.

Just make sure to email me because I so busy with remote tunes for various builds and drifting teams that I am rarely on Zilvia haha - I try though

[email protected] or direct message me on my fb page: https://www.facebook.com/shadowerks

Thanks

what bullshit. if you know what the problem is why do you not post the answer here for everyone to see? why do you ALWAYS try to solicit business on this site when a member has a problem instead of sharing your knowledge which is sub standard in the first place? at least go back to pm the op instead of this bullshit. spammers like this is why this site has gone down hill so far in the last year.

to the op. have you tried a different maf or checked continuity of the wires to the maf? i see your in alberta i can recommend a shop in the north, central or southern part of the province depending on your location that you can take your car too if you feel the need to pay someone to fix this. they all have experience with sr20 engines.

[se7en_]

I have checked the maf wiring. Grounds are good, and shows 1v with engine off and 1.42v at idle. 12v was good too. Tried a different maf too. I'm running a stock ecu with daughter board. Tuned to z32 maf and 550cc.

[Def]

Did you just install the ROM tune, or were you running it before the cam install?

[se7en_]

rom tune was run before. Ran great.

[civicej8]

I know you said you did a boost leak but what about your intake manifold gasket?

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[se7en_]

I'm checking that tonight with a smoke machine. I'll post what I find.

[se7en_]

Smoke machine found two tiny leaks after the throttle body, one at the brake booster vacuum port. Repairing both didn't fix the problem.

[se7en_]

I'm going to set the timing with the spark plug wire method. maybe my pigtail wire is acting up...

[inopsey]

provided everything else is right, (timing etc) when you changed your head gasket you maybe changed the cr of the engine by using a different thickness? maybe your ve has changed and you need a retune. the head work and cams would also changed the ve of the engine.

[se7en_]

I doubt it would change enough, and its not ve tuned, its maf tuned.....unless I'm wrong?

[inopsey]

do you get a stable maf voltage at idle or does it fluctuate?

ve refers to the efficiency of the cylinder; how much output (power) per volume written as a %. more/less efficient flow threw the engine will change the ve. if your tuning for power you always try to achieve max ve in every cell. maf or map doesent matter here. changing the compression (difference thickness headgasket) of the engine will change the ve at idle. anything that improves the air flow in the engine will theoretically change ve, whether its enough to put the tune off so it wont idle is a guess without a wideband. adding forced induction will change the ve when the turbo is forcing air into the engine with boost.

you tune ve at idle for afr (14.7-16afr) and timing to give a steady idle. ve of an engine changes from altering how air flows through the engine.

[Nikzilla]

I agree with inopsy.

Considering the changes you've done to your head, you've probably significantly altered the ve of your head, resulting in your tune being too harsh for the engine.

When you unplug the MAF, the ecu goes into safety mode, running a much more conservative tune. This would explain why you can idle without the MAF.

My suggestions are to try to retard the timing, or if you have an adjustable FPR, increase fuel pressure. See if it will idle with the MAF under those conditions.

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[se7en_]

I see what you are saying, but really, the head was decked about 0.007" and the head gasket is approx 0.015" thicker than stock...really not much difference. And the 5 angle valve grind shouldn't change anything(I'm and engine rebuilder, and I've done a few heads that didn't need a retune.

Regarding the cams, It still idles smooth with a steady maf signal. 1.42v at idle, which is what most people have when idling with a z32 maf. Maybe I'm wrong here?

[Nikzilla]

I see what you are saying, but really, the head was decked about 0.007" and the head gasket is approx 0.015" thicker than stock...really not much difference. And the 5 angle valve grind shouldn't change anything(I'm and engine rebuilder, and I've done a few heads that didn't need a retune.

Regarding the cams, It still idles smooth with a steady maf signal. 1.42v at idle, which is what most people have when idling with a z32 maf. Maybe I'm wrong here?

That means that you actually lowered your CR, hmm.

Can you describe exactly how it dies?

Also, a valve grind does affect VE since the gasses flow around them. It's a pretty subtle change though.

[se7en_]

I agree. When i start it, it idles up to approx 2200 rpm for about 3-5 seconds, then it stumbles for a second or two and then quits.

[se7en_]

I should add that it starts right up everytime.

[Nikzilla]

I agree. When i start it, it idles up to approx 2200 rpm for about 3-5 seconds, then it stumbles for a second or two and then quits.

How certain are you that your mechanical timing is dead on? It's pretty easy to skip a link when reassembling the valvetrain.

Did you do a compression test to make sure your head is airtight?

Do you have a consult port?

Try to advance or retard the timing and see if you can get it to idle that way.

[se7en_]

I don't have a consult port on this car unfortunately. I am quite certain on the mechanical timing. I'll do a comp test tonight, but I wonder what it should be with my cams...I've seen as much as 50psi lost with cams.

I have messed with the timing to no avail...

[Nikzilla]

I don't have a consult port on this car unfortunately. I am quite certain on the mechanical timing. I'll do a comp test tonight, but I wonder what it should be with my cams...I've seen as much as 50psi lost with cams.

I have messed with the timing to no avail...

Count the links.

http://www.sr20forum.com/gallery/data/500/CamPulley_resize.JPG

Also, are you trying to mess with the timing alone? Because the way I do it is, I have a friend start the car with my right hand on the CAS and my left on the light, and I rotate it as it starts dying to keep it alive. If you're just rotating it a bit and starting, you won't be able to keep it alive.

[se7en_]

i'll check the mechanical timing tonight as well.

[se7en_]

Oh boooooooo. I just happened to check the resistance of the coolant temp sensor tonight. No continuity. I guess I should fix that before attempting anything further!! On a side note, I sure wish my ecu still had a working led so I could check codes.

[se7en_]

Double post

[Kingtal0n]

That means that you actually lowered your CR, hmm.

Can you describe exactly how it dies?

Also, a valve grind does affect VE since the gasses flow around them. It's a pretty subtle change though.

changing around the compression with head gasket thickness and deck beef will not affect an engine to the point where it will no longer idle.

This is a far far overcomplication of this issue. The problem is much more subtle.

I asked you to create a boost leak and determine if the engine would idle. I assume you never tried that. I suppose you want reasons.

1. If the engine did idle with a boost leak it would tell us the maf output voltage is too low (engine starving for fuel)

2. if the engine did NOT idle with a boost leak increasing in size we would next test to determine that the maf voltage is too high (too much fuel)

MAf voltage is parabolic so this will not hold at any RPM above idle. Clearly if the engine is able to idle with no maf connected the problem is a communication issue involving the fuel/fuel map and associated variables (any sensor altering fuel)

[se7en_]

Interesting. I will mess with that tomorrow when my CTS is in. Thanks for taking the time to write all that out.

[se7en_]

Could I just raise and lower my fuel pressure?

[Nikzilla]

Could I just raise and lower my fuel pressure?

Yes

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[Kingtal0n]

how is raising your fuel pressure going to tell you if the maf is working? How will it tell you if the computer is adjusting fueling based on maf inputs?

how will you know if the maf is related to the source of your issue?

[Nikzilla]

King. U always blame the MAFs.

MAFs are cute. Stop the hate! Show MAFs some love.

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[Nikzilla]

I reckon if the hotwire looks clean and the voltages are within spec, it's incredibly unlikely for it to be malfunctioning.

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[Kingtal0n]

how do you know the computer is even reading the maf? Maybe when he plugs in the maf it doesnt even get a signal from the maf- only noise.'

You cant look at the hot-wire and tell if the computer is reading it.

And it's not like this is a difficult process to test. I am not telling him to rebuild the engine, only loosen a clamp ~ 2 minutes for some critical information.
Instead of just assuming that because it looks clean that it is working.

[Nikzilla]

He could read the voltage from the ECU harness connector. This is why consult ports are nice.

Also, if it read only noise, the ECU would register a malfunction and go into safety mode. It would ignore the input, wouldn't rev past 2.5k and it would behave exactly as if it was unplugged. The fact that behavior changes with the MAF plugged in rules that out.

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[Kingtal0n]

voltage does not tell all when it's a Z32 maf on an sr20det, especially through a tuned ECU. What did he compare voltage to? There is no set standard, and a little change as 0.5V can be a big difference on that maf.


I think the problem is a boost leak. Maybe by playing with the couplers he will find one.
Because if there is no boost leak (what psi did you fill the plumbing to?) And all the wiring is good, that only leaves: ECU / sensors malfunction

setting aside the fuel system because it runs with the maf disconnected, and acknowledging good compression.

[Nikzilla]

A boost leak so large that it stalls the car would be hard miss.

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[se7en_]

There isn't a boost leak for sure. 10psi easy and smoke tested it as well.

[se7en_]

I'll check all the things listed and get back to you tonight.

[se7en_]

Well, I changed the coolant temp sensor for the ecu and now it idles for a few more seconds before it stalls. And it struggles to run right before it quits.

I tried to raise and lower fuel pressure by 5-20psi with not much change, ect it smells super rich when I raise fuel pressure

[se7en_]

I'm going to try setting the timing with a spark plug white method.

[Nikzilla]

This is obvious, but check grounds. I mean like religiously check them. Get a guide and find each one individually, and test for continuity between the connector and the chassis/terminal

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[se7en_]

I went through that already. I even sanded the paint before I bolted the grounds to the body.

[se7en_]

I have to double check, but I think it runs the same with the iacv unplugged as well.

[se7en_]

a couple things I'm going to check....

gap plugs to 0.036"
check timing with plug wire
clean iacv
clean maf
double check mechanical timing

[se7en_]

Ok. update.

I bought new ngk 6 heat range plugs. That helped, but still no idle.
timing was double checked and all good.(mechanical and CAS timing checked with plug wire method)
cleaned maf and iacv

Overall it seems to be better, it'll startup great everytime, then idle high for 5 seconds, then drop to 2-300 rpm and studder there for maybe 5-8 seconds then stall.

I'm sure I'm getting close here.

I turned out my IACV a few turns, but that didn't help.

Could the PROCAMS just be a little too harsh to keep this idling?

[Kingtal0n]

What cams did you used to have,

and what cams do you have now.

Did you ever try the boost leak idea. That could also temporarily "fix the problem" if it was related to reversion caused by the camshafts.

And I've seen instances where the wrong camshafts (solid lifter type) were sent by accident. Check your part number on the cam itself.

[se7en_]

Stock cams before Tomei 260 procams now
I tried the boost leak idea as well as raising and lowering fuel pressure with no luck

[Kingtal0n]

If the cams are to blame, then adding air and fuel would help the engine idle. The idle might be rough because of the camshafts, have you ever had a set of real cams before?

I am not sure why you chose those camshafts. A much better option would have been S3's. Oh well now. Another possibility is some of the headwork went sour. Did you ever do a compression / leakdown test? I forgot what you had already tried.


In any case, like I just mentioned, adding air and fuel would help idle a rough camshaft. If you crack the throttle open and raise the fuel pressure, and you get a nice rough idle, that is probably how it is supposed to sound. You would then only need to adjust the IACV open more, and add fuel to the tune at idle. This is very common, for camshaft modifications to require additional air and fuel.

Have you tried driving the car? If the problem is related only to the camshafts, then the vehicle will drive pretty normal- it just will not idle without adjusting the fuel at idle (and air).

[Kingtal0n]

http://www.youtube.com/watch?v=YUHZBrW7_UE


procams at idle, not sure which, but notice the engine doesn't sound smooth.


Smaller cams than yours
http://www.youtube.com/watch?v=i_nVUxmoY7E


still not smooth

tuning an idle with a rough camshaft can be an art. it depends how you want to drive the car. If you had a power FC i would modify your map real quick and show you what to try.

[Chaluska]

Se7en, im having an identical problem to you, only on a recently installed KA.

have you made any progress? My car starts, and fires up to about 2300 rpms for a few seconds, then stumbles, and proceeds to die.

Throttle has no effect on the engine. i cant free-rev it to any RPM, it just dies.

does yours do this as well?

[se7en_]

I can free rev mine. It seems to really try idling at like 200 rpm for quite a while before it quits, but it always stalls.

[Chaluska]

as a minor update to my situation, i swapped in my OE injectors / MAF and ECU, and the car fired up, and idles and revs fine.. time to dig through the MAF / ECU / injectors problem.