7MGTE head banger. Need some input.

[IDISLIKEMK3]

Ill try to be as short as possible...
91 supra,manual, turbo, 550 siemen injectors, aem wideband, apexi neo, aeromotive FPR, upgraded ct26.greddy profec spec2 11.5psi About 2k since motor was put together.

This is a buddies car that I work on more then I would like to. He has an NA that I rebuilt that was a pain and it has never came back. I seem to be fixing the person who put the motor togethers shortcomings, Most issues are pretty straight forward, I have replaced all the gaskets on the turbo/exhaust side because whatever cheap gasket kit they used it, each one is just blowing out. So I did them all in oem gaskets, including EGR cooler gasket. No problems so far. Now to the current shituation.....

The egr gasket and the gasket between lower plenum and egr blew out. The injectors were leaking and so was the fuel dampner. So I ordered all factory gaskets and slapped it together, alot better then it was. Upon first start it seemed like it had a crazy vacuum leak and wouldn't idle. So held idle about 1500rpm for a little while it warmed up and bled coolant. And I know it seems whenever I reset ECU(unplug battery) It takes a bit for it to run right. Has to learn things I guess. So took it for a drive up and down the mountain near me and it ran better then I remember. Parked it for a few days at the place I do the work at until I could pick it up. Drove it to work and about half way there it started hitting fuel cut and warning me of overboost at about 10 psi... and running funky...pulled over..made sure I didn't blow a intercooler hose and all was fine. Restarted car and switch boost contoroller from high boost to low boost and back. Ran fine all the way to work.


Left work...got on freeway with a heavy foot, Started hitting fuel cut and low boost again and then check engine light. Code 71. Got to my buddies house. Did a little visual inspection cause motor was hot. Pulled efi fuse for a min. Restarted waited ten minutes, test drive...Car would not idle. Whenever throttle was closed car would die. AFR was around 13's when under boost so no bueno. Limped it home and after having about 30 minutes to check it out after work or so the last week... I found a vacuum leak to the VSV for the EGR(explanation for code 71) and a kinda big boost leak to the coupling to the intercooler on the cold side. I used a smoke machine to do the test cause even with nifty use of a rubber glove and duct tape for the turbo inlet I couldn't get it to hold a seal with the air pressure test. I tested the intake with the smoke machine in the brake booster line and covering the throttle body and found the VSV line and the actual egr leaks through the diaphram a little bit. After reading that might be normal for supras??( see below) Tested the cooler piping with a pvc setup and glove and duct tape. Found the boost leak at the intercooler and nothing else. Fixed them both...Still runs like shit. Seems to be worse.

Fuel pressure static is like 50 and under vacuum is 40. Which I think is to high, but he said that is how it was tuned...I adjusted it per the TSRM and no change



I tested the egr off the car and the diaphragm held vacuum. But when I (should've seen me doing this) plugged all the ports and supplied vacuum to the diaphragm and put the smoke machine in the head side of the EGR and smoke came out of the holes that are on the bottom of the diaphragm. Not alot but I don't think it is suppose to.


I don't think I forgot anything. But any helpful hints from someone who know or has dealt with this motor before on other things I should check I would appreciate it.

Going to check the IACV tonight as far as operation goes.

 

[Nick M]

If you don't have 34, you do not have "abnormal turbocharger pressure" and the associated fuel cut off. An EGR valve that is stuck open, even just a little, will cause the idle to be rough. If you pull it open at idle it can cause a stall. A leak to atmosphere through a gasket will make that 71 appear for low temp, as you suspect.

 

[IDISLIKEMK3]

Forgot to kinda add... Initial start when cold it will idle fine at around 800-1000 rpm for approx 45sec then slowly become leaner and idle drops to around 500. And with the egr.. The removed it and blew Air through the intake side it was solid. Just started it and applied vacuum to top hose and car stumbled almost died until I released. So I'm assuming stuck egr isn't the problem.

 

[IDISLIKEMK3]

Iacv failed the Tsrm test. Passed in resistance but when power supplied to pins and the others grounded... The plunger just twitched. Took it completely apart and cleaned it and verified the shaft wasn't frozen and zero change.



EDIT: IDLE CONTROL VALVE IS FINE.

 

[atmperformance]

thanks for updating us on what you found, and pictures of the Iacv?

 

[IDISLIKEMK3]

here is a video

http://youtu.be/9QTjWQLwZdc

 

[3p141592654]

Disconnect IACV before starting and it should run at fast idle permanently.

Listen for clicks when shutting the engine off to validate it is moving.

 

[IDISLIKEMK3]

I would have to warm the car up a little bit to hear any audible clicking correct? Or is the clicking the IACV closing which would mean it would click no matter the temp?



But would the leaky EGR and the stuck open IACV cause a funky really lean idle?

 

[hvyman]

After you shut the engine off the ecu commands for the iac valve to be reset to the full open position. Which is the clicking noise you will hear after shut off.

 

[IDISLIKEMK3]

So this weekend I had some time to check all the pins to the ecu for correct voltage and remove wire harness and check for broken wires. Nothing. I knew deep down inside I was doing the test wrong for the IACV because the ohms test checked out. So after knocking my head for a bit and reading the TSRM over and over I realized you are suppose to just momentarily ground each pin instead of leaving the ground on the pin. It is a stepper motor, so it works fine. I installed it back on car and tried starting the car twice and it wouldn't even idle....almost ready to push this thing in the road and tell my buddy to come get it. Hopefully have a few minutes tonight to quadruple check all vacuum lines for correct orientation etc

 

[hvyman]

If the iac is not in the full open position it will take a few times of starting it and turning the key off and waiting for the cor relay in the passengers kick panel to kick off and then repeat until the valve is fully open when shut off.

 

[IDISLIKEMK3]

I actually just signed on to ask this question. If it would reset to full open by itself causeI think I installed it in full closed position and that's why it has horrible idle. Thank you ill give it a few start and possibly a drive down the street and back

 

[jetjock]

If the iac is not in the full open position it will take a few times of starting it and turning the key off and waiting for the cor relay in the passengers kick panel to kick off and then repeat until the valve is fully open when shut off.

Say what?

 

[3p141592654]

Yeah really, the ECU is programmed to continue opening the IACV at shutoff after it reaches full open to make sure it is really fully open.

That said, I think the IACV has nothing to do with any problems here. I would check first that the EGR is not stuck open all the time as Nick suggested above.

If it was mine, I would put the injectors back to stock and delete the Neo and would be very surprised if it didn't start running properly again.

 

[hvyman]

Ive found it will not do it in one pull. Usually took about 5 times. That was on a 1jz but still same 6 wire iac.

 

[IDISLIKEMK3]

Took about 2 times on and off for it to start clicking. As soon as i hit throttle though it threw a code 31. As soon as that happened I realized I forgot to plug in the L-shaped vacuum line underneath the intake that goes to the air control valve underneath the water pump area. Plugged it back in but didn't have enough time to reset the code and restart the car. But the oddest thing...It almost idled perfectly when that vacuum line was disconnected......only went funky when I touched the throttle.:: hommer :: I really hope today when I get home and clear the code it idles and runs. Fingers crossed

 

[IDISLIKEMK3]

Yeah really, the ECU is programmed to continue opening the IACV at shutoff after it reaches full open to make sure it is really fully open.

That said, I think the IACV has nothing to do with any problems here. I would check first that the EGR is not stuck open all the time as Nick suggested above.

If it was mine, I would put the injectors back to stock and delete the Neo and would be very surprised if it didn't start running properly again.

Egr is not stuck open. I had it off the car and tested it. Only issue was it leaked through the shaft a little bit. As soon as I finished the car I blamed the tuning, electronics. But his tuner and him blamed something else.I fixed his fuel leak and his giant exhaust leak...so idk. Thats why I have resolved to asking here in a forum..which I rarely do but I know these motors can be finicky and I have exhausted the patience of one of the techs at my work who owns multiple insane mkIV and has worked on a couple mkiii, he hates them and his current answers to my questions are "Just tell him to fucking sell the thing now while it still kinda runs". I have basically checked everything I touched to make sure nothing was installed incorrectly etc.

 

[jetjock]

First, these motors are only "finicky" when the people who try to repair or mod them have limited EFI knowledge in general and of this car in particular. It's a very simple system compared to OBD-II. Second, if you're looking for advice here you'd better be able to sift through the crap. Frankly, the TSRM and a solid knowledge of the fundamentals are a far better bet...

 

[IDISLIKEMK3]

I have really good knowledge in motors in general in rebuilding etc etc but when it comes to diagnosing electrical grimlins or turbo stuff...thats where I can be limited usually, and I actually work for toyota, So the TSRM has been alot of help. I have seriously exhausted everything I can think of and a few of the seasoned techs are a bit stumped. And as far as sifting through the crap...I def take everything with a grain of salt when it comes to forums. And that i have been taught by a mechanic that has 42 yrs under his belt and is highly sought after and been working on cars since I was about 13, I can sift through crap pretty well. But I am def still learning

Everything that leaves my house, leaves 100% better then when it came in...this car on the other hand..is a whole diff story. Mostly cause idiots and the owner have had their hands in it.

Thanks for the tip on the ISCV jetcock I appreciate it. I just found it odd that it idled fine with the vacuum leak and on the afr it was bouncing around 14.7 which it usually isnt that smooth. It should have been on the leaner side of things... I guess Ill find out when i get home.

 

[3p141592654]

A code 31 is not from a vac line falling off. Only a handful of things will cause a code 31, and they are:
1) wiring between AFM and ECU bad
2) AFM bad
3) ECU bad (highly unlikely)


Now, given the Neo is between the AFM and ECU, you can guess what I think the problem is, but if some joker "cleaned" the AFM with solvent or is running an oiled K&N then it could be the AFM.