NO IDLE on SR20VET

Enjoyer

New Member
Really sorry for the long post, but I think it needed to be clearly explained because of the apparent complexity of the problem(s).

Here's a link to a video showing the issue :


Let's talk about my GTI-R. I owned it for 3 years now and drove it only 1000 km, the first summer.
At first, it was supposed to be a tiny project, it only needed some basic parts and we were good to go. But things went terrible. It's been 3 years and it still not idling.
So, let's start at the beginning. I bought it from a good friend of my roomate. He himself bought it from a guy that claim to have put around 50 000$ on it (including importation fees, taxes, repairs and upgrades). For all the time that the last owner had it, things went pretty good. The engine never had a great idle, but it drove perfectly and pulled very well. He had nothing to do on it until the engine blew out (not sure why!). At that point, he decided to rebuild it and to prepare it to make huge power. So he installed some forged rods and pistons, a fuel pump, a fuel pressure regulator, etc. He was planning to put a huge turbo on it to make in the range of 500-600 whp. The engine was built and installed by a professionnal. The only missing parts were the huge turbo, the manifold and a rad (he sold it, not sure why). Then, the owner decided to sell the car because he lost interest in the project and had another one in mind.

So I bought it and putted in all that was needed. I decided to put the same turbo than the last setup (precision 5130) and to forget about the huge turbo setup. The first start was perfect. We did the last tiny remaining things then I began to daily drive the car. The car drove perfectly, no sign of hesitation, idle was ok even if it was running a little rich, but nothing bad. So I drove it on around 1000 km to break in the engine (it hadn't been drove since it's rebuild). I even went for a weekend in my hometown (250 km away) without any issues. It's even surprising how a car from the early 90's can feels that smooth on the road, almost like a brand new car (not joking).

So, almost a week after that, I took the car to the shop where I work to put some goodies on. It was parked outside for 2 rainy days. After 5 minutes of driving, it became to run VERY rich. It went to 10 on my A/F gauge (the smallest value on the gauge). No matter if I was idling or pulling, it was dangerously rich. So I parked it at the shop.
We tried a lot of things : changed the MAF (two differents), made the injectors cleaned and tested, changed the O2 sensor, changed the ECU, etc. (I probably forgot something).

So, all this work for absolutely nothing. The car was still running extremely rich (on idle only because at this point I didn't wanted to drive it anymore to make things worst). So I called the tuner to know if he could tune it like that and he told me that there's no problem, just bring the car and he'll tune it and it will be fine. That's what I did. And that's what he did. He struggled to make it idle correctly at first, but finally succeed. He made some pulls and everything was alright. The car was still stalling after a pull, but nothing bad. Then one time it stalled and refuse to start again. He tried a couple things, scraped a couple grounds, pulled a couple hoses and suddently it started (i'm not sure why - him neither). He was able to tune it correctly, even if I still had a little A/F mixture problem. Thats why he decided to stop to 347 HP and 364 Ft-Lbs torque, even if the engine and turbo had much more potential than it. He tought it was a bad MAF problem and that changing it will solve the problem.

So I came back home and when I installed my new MAF, I noticed that the piping between the maf and the turbo was loose ! I pulled and it came out...I've forgot to tighten the flange around the pipe...I tightened it and went for a ride. No more rich trouble ! I was so excited that I ran right into a traffic jam without noticing. It really tested the setup because it used to run richer when stopped. I had absolutely no problem in the traffic. I was two corners from home when it began to run like shit. It was idling high, then struggling to idle (had to give more gas so it won't stall). I parked it and it's there since that moment (4 months ago).
Since then we made new grounds directly to the battery, checked for leaks in the turbo/intercooler pipings, checked the TPS and the IACV, changed the spark plugs, checked the fuel pressure regulator, checked the fuel pump, checked the timing, checked for codes on the ECU, etc. (I think I forget something). We checked all the wiring (the better we could) and the only thing we found is a cutted MAF plug wire and a cutted injector wire. What's strange is that even soldering these wires haven't changed anything. By seeing it we could guess that the wiring dried with the time and that we may have to change the entire harness. That's where I am stuck now. I'm currently looking for a good harness, but it will be a lot of trouble to change it, so before doing it i'm asking to you guys, what do you think it is ?

I'm really desperate now...it was supposed to be a tiny project and it's been 3 years and more than 10k $ later and I can't enjoy my car.

(I know that the best upgrade is to install a complete engine control system like AEM does, but I reached my money limit for this project for this year.)

Here's a link to a video showing the issue :


Thanks for reading and sorry for the long post.

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zia

Active Member
looks like idle control valve is not working properly.its at the back of the manifold with 2 pin connector,does vehicle idle ok when warm?

Zia
 

Enjoyer

New Member
looks like idle control valve is not working properly.its at the back of the manifold with 2 pin connector,does vehicle idle ok when warm?

Zia
We checked the idle control valve and it seems to work properly.
And it's not idling better when warm.

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zia

Active Member
We checked the idle control valve and it seems to work properly.
And it's not idling better when warm.
How did you check this? which one did you check? try the below
1 : IAS Idle Air Screw. Its part of the IAA ( Idle Air Adjust unit which sits under the right hand side of the plenum chamber ). Used for setting the base idle speed. Is a slotted screw on the side of the IAA and can be seen under the plenum chamber.

2 : AAC Auxiliary Air Control valve. Also part of the IAA unit, this is the main solenoid that the ECU uses ( in conjunction with the Throttle Position Sensor ) to regulate the idle speed. Looks like a round tube fixed onto the IAA unit.

3 : FICD Fast Idle Control Device. Also part of the IAA unit, designed to raise the idle speed whenever the engine comes under heavy load, ie, when aircon is switched on etc. Looks like a small round tube with hex shaped sides, screws into the IAA right next the AAC.

4 : IAR Idle Air Regulator. Sits underneath plenum, works like an automatic choke ( but just for air ). Always switches on whenever you start the car and works on temperature, cold means open ( higher idle ) and gradually closes when intake heats up ( 3 minutes or so ? ). It has a heater inside so will always come on whether the engine is hot or cold and gradually close over the 3 minutes or so. Looks like a small cone with a disc stuck on the end with a pipe on each side.

5 : Worn throttle butterflies / throttle housing. Air leaking past butterflies or leaking in through the spindles.

6 : Throttle balance screws. One screw on each intake, used to balance the four butterlies at idle, can cause high idle if all are adjusted too far out. Can be found on top of the throttle body next to the injectors.

7 : Vacuum ports. One port on each intake that is used with a vacuum guage for balancing the throttle bodies ( see #6. ) Should have rubber boots blanking them off but have been known to disappear... Found next to the throttle balance screws on top of the throttle housing.

8: Igniton too far advanced at idle. Should be 20' +/- 2' for a standard car.

9 : Throttle butterfly stops incorrectly adjusted. Stops the butterflies from closing properly. One screw for each pair of butterflies, usually sealed in place and a right beach to adjust

10 : Accelerator pedal / cable not adjusted properly. Butterflies not closing fully, similar to #9.

11 : TPS Throttle Position Sensor fault or maladjusted. Gives the ECU wrong indication of whether the engine should be idling or not, see also # 2.

12 : Blow off valve leaking. Allowing air to blow past diaphram under vacuum.

13 : Air leak from any of the 3 billion pipes that connect everything above. The pipes are all rubber and do perish over time....

14 : Inlet manifold gasket or Plenum gasket leak.

15 : Faulty Lambda sensor. Used to set the mixture to approx 14.7:1 at low engine speeds / loads. Can cause mixture problems and uneven idle. Can be found on turbo exhaust ( dump ) pipe, bottom left hand side of the engine.

16 : Aftermarket fuel controller set incorrectly. Can be a problem on Apexi PowerFC ECU's where the 'electronic' base idle is set too low for the actual 'mechanical' setting. Causes the idle to hunt and jump around as it tries to achieve an impossible target.

Zia
 

gtiroz

Administrator
Staff member
17. Engine coolant temp sensor. Part of the overall control system (used in fuel injection, ignition timing, idle speed, wastegate valve and radiator fan control). Found under the intake manifold on the RHD drivers side (22630-51E02).

Worth noting that if the tune was done when you had a major air leak (and the leak was fixed afterwards) then the tune will be way out...

EDIT: Just watched the vid - try deleting the tune on the ECU.
 
Last edited:

Enjoyer

New Member
17. Engine coolant temp sensor. Part of the overall control system (used in fuel injection, ignition timing, idle speed, wastegate valve and radiator fan control). Found under the intake manifold on the RHD drivers side (22630-51E02).

Worth noting that if the tune was done when you had a major air leak (and the leak was fixed afterwards) then the tune will be way out...

EDIT: Just watched the vid - try deleting the tune on the ECU.
Is there a way to make a backup file or the tune will be definitely gone ?

The car had a terrible A/F only with the base map, but again it could be the air leak. At least it had a steady idle.

But if that's the problem does it mean that i'll have to make it tuned again ?

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gtiroz

Administrator
Staff member
Yeah you can download the ROM (BIN) file before you reset it - and reapply it later if you wanted - although need the correct software to do so - what brand is the chip/board?
 

Enjoyer

New Member
Yeah you can download the ROM (BIN) file before you reset it - and reapply it later if you wanted - although need the correct software to do so - what brand is the chip/board?
Unfortunately I don't know the brand of the chip. My tuner did everything by himself and I didn't ask.

I can ask him, if it's important to know it. But anyway I don't have any of the software needed, so I guess that i'll have to send him the ECU to delete the tune ?

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