Hot idle issue with 7A EX cam

[S2central.net]

So why would maf / turbulence be different when hot vs cold ?

Cos it sucks more air when cold I guess but it looked a nice steady value when warm idling on maf - once it settles down but still lumpy. Might be worth setting idle speed even higher for now as a short term fix. It's currently 960rpm. It will idle beautiful at 800 on cold though.

[jonaper]

Did you guys find any answer to this problem?

I have exactly the same problem. Car has bad idling when warm, sometimes it stalls, (especially in uphills rarely enoug!)

7A cams on my car. Timing is fine.

Pressure tested (no air leaks), changed lambda, MAF, temp.sensor, TPS, ECU, software + +. I'm going crazy.

[prj]

Usually stalling is a faulty closed throttle position switch, vacuum leaks, faulty dump valve or the duty cycle for ISV has not been set correct in Motronic.

I never had to adjust the ISV duty for a 7A exhaust cam though.

[Thuppu]

I couldn't get rid of the problem with a different ISV and by-pass. Issue was there with stock cams and later with 7A ex cam, also before mapping and after it. Later I had a couple of minor leaks, but when I got them sorted out the problem was still there. The throttle position swich was the only one I didn't touch.

[jonaper]

Usually stalling is a faulty closed throttle position switch, vacuum leaks, faulty dump valve or the duty cycle for ISV has not been set correct in Motronic.

I never had to adjust the ISV duty for a 7A exhaust cam though.

I have both inlet and exhaust 7A cams. There's no vacuum leaks. I have also tried a ISV and TPS that i know works fine on another car.

Is it possible to change the duty cycle on the ISV?

[prj]

In Motronic?
Yea, it is, there is a map for ISV linearization.

But I only ever needed to touch it, when we had catcams on a car, and the car needed to idle at about 1200-1300 rpm.

I never had issues with 7A cams.

Is your dump valve recirculated? Is the outlet of the dump valve looking into the turbo?
Somehow I don't think the problem is with mapping... I've mapped so many cars with 7A cams, and they all worked fine with 900 rpm idle.

P.S.
Of course if you are running some lottery software with random injectors or your tuner does not know what he is doing, everything is possible.

[jonaper]

In Motronic?
Yea, it is, there is a map for ISV linearization.

But I only ever needed to touch it, when we had catcams on a car, and the car needed to idle at about 1200-1300 rpm.

I never had issues with 7A cams.

Is your dump valve recirculated? Is the outlet of the dump valve looking into the turbo?
Somehow I don't think the problem is with mapping... I've mapped so many cars with 7A cams, and they all worked fine with 900 rpm idle.

P.S.
Of course if you are running some lottery software with random injectors or your tuner does not know what he is doing, everything is possible.

Yes it's resirculated dump. I have also try to change it to the original in case it doesnt close as it should.

The software is real stuff and have worked fine before. I have also tried with another ECU and another good software just to eleminate it out.

Next step i think must be to change the fuel pump, filter and injectors... or at least measure the pressure.

[simon20vq]

Interesting this because I have just change my turbo, injectors and associated parts. Also replaced all the breather system for new silicone hoses and now have the same issue you are discribing! Hope you post your finds Paul, I'll post mine if I find the problem. I was thinking lambda because I was in that area alot and wondered if a wire could have broken in the plastic sleeve. Only other thought is a vacuum pipe.

[prj]

The software is real stuff and have worked fine before. I have also tried with another ECU and another good software just to eleminate it out.

So your car is not custom mapped for your setup?

I guess I am finished with this discussion in that case.

[jonaper]

So your car is not custom mapped for your setup?

I guess I am finished with this discussion in that case.

It's custom mapped yes. As i wrote it worked fine before, and there has not been any changes on the setup.

[Jamo]

I had 7a cams in my 2.2 and never had an issue with the 850 idle Mihnea put in the ecu. I notice on mine with NM cams I have to raised idle to around 850-900 also on vems

I do think 7a's don't like low rpm idle, whether this is just a coincidence I can't say.

A lot of people had success moving the maf to the pressure side for better or worse to resolve this issue also for example Ross and S2_Bo but it's probably a band aid not a root cause solution.

[prj]

It's custom mapped yes. As i wrote it worked fine before, and there has not been any changes on the setup.

Okay, in that case make sure it's not sucking extra air into the system after the maf.
Have you tried pressurizing the intake *from* the MAF? Not after the turbo?

Moving MAF to pressure side only changes the fact that there are no more leaks after the MAF.
Or if the dump valve is set up incorrectly and causes lots of turbulence, it'll take care of that as well. It's not fixing the root cause though.

[jonaper]

Pressure tested from the maf, of course. No leaks.

Will try to change the resirc valve and fuel pump. Thank you anyways

[prj]

Fuel pump is waste of time, if you had fuel pressure problems, they would be evident on high load, and not at idle, where there is excess fuel.

Maybe it is sucking air through PCV system? Hoses broken, or for example dipstick not tight?

Also, do you have any fault codes at all in the ECU?
When you lift off, the engine moves. So it is possible something is losing contact at that moment.

[jonaper]

OK. Now & then i get the 00561 mixture adaption or 00533 idle speed regulation.
Car runs good on full throttle, no problem. Idle is good on cold engine.

When the engine is warm i get a smell of fuel and bad idle.

I run with catchtank/filter for the oil breather system so there's no pcv valve. I had to remove some hoses ++. Maybe that's the problem? If it's sucking unmetered air since the valve is away? I will try to put the valve back and see whats happening