Supercharged e36 M3 idle A/F

[gabordi]

Hi all,
There is an idle situation that I try to resolve. Idle is bouncing a bit and A/F is changing. One affecting the other.

Here's a link to the video:

https://www.dropbox.com/s/qme85dodis...75456.mp4?dl=0

Does somebody have a clue?

Thanks

[328 Power 04]

I'd say you either have a vacuum leak or the tune needs a lot of work.

[gabordi]

Thanks for comment,
I've been pressurizing the system to about 1psi with a smoke machine and nothing came out so I figure it's not a leak

Tune's from RK tunes, should be on point. Everything's good unless the idle. This idle is just annoying

anymore ideas?
thanks

[328 Power 04]

If your throttle body is fully closed at idle as it should be, this is completely out of the tune.

[gabordi]

Throttle is fully closed and cleaned 2 weeks ago. TPS signal is at 17 percent when throttle closed. I dont know if this is a normal reading. Signal goes smooth to 100 percent.

I understand that the tune is programmed to change parameter with signals from sensors. For a change of parameters, somethings gotta change. But with no input from my end, what could be changing sensor datas?

Thats what I'm trying to figure

[Pavlo]

Almost completely certain its the tune. Factory computer does change AFR up and down as it idles, but way smaller changes. I am pretty sure this is whats happening here but the bigger injectors make it do way larger swings. For some reason nearly everyone thinks a wide open dynojet "tune" is all you need. In their defence, you also shouldn't expect an $800 recalibration have the refinement of a what a team of engineers did in the first place.

[gabordi]

Thanks for the input Pavlo,

After all the tests and parts replacement I've done, I am leaning towards the tune also. I'm sure it could be easily fixed though because 42 lb injectors are'nt big injectors compared to bigger set-ups running way more hp numbers and idling better than my car. I'm going to log the car with bmw logger and send the datas to my tuner and hopefully find the culprit!

[E36M3LX]

for forced induction, you should be doing a boost leak test, not a smoke test. you need a boost leak tester to force at least 15 psi of compressed air in the system and then spray all connections with soapy water. you will be amazed at the leaks you will find.

[328 Power 04]

Right, but at idle, none of that matters.

- - - Updated - - -

You can start to progressively close the idle control valve out of the tune, since the factory control of ICV doesn't match when there is a compressor making a little bit of extra air at idle.

Other considerations: wrong injector dead time placed in the tune; physically the MAF is in a bad location or not experiencing laminar flow, etc.

[Germbmad]

My vote is: out of tune, as well, did you figure it out or get it fixed ?