Hunting on idle once up to temp - Ethrottle

[Brody Walker]

Hi all,

 

Hoping to get some help. I have a Bosch DBW throttle hooked up to be R34 Gtt with a g4+ & never been able to get the idle just right. It does the below:

 - Coming to a stop it hunts 3 or 4 times before sorting itself out. In some cases it dies. The hunting almost always occurs but the dying only happens when at operating temp. I adjusted the ISC Base position up from 0 to 0.6 for ECT 70+ which seems to have helped with the dying. 

- When rolling in neutral or with the clutch in it hunts the whole time the car is rolling & sorts it's self out once I'm stopped. Here's a log of it, check out from 40 to 1:22. TP is steady, don't have VCT kicking in, can't seem to see something else at play.

 

Thanks for your help.

Idle Hunt when rolling 10-12-22.llg Idle adjust 2 10-12-22.pclr

[Adamw]

I suspect in these high vacuum overrun conditions you are commanding an injector pulse width shorter than your injector can actually open with.  You can see the lambda pegs full scale lean whenever the inj PW drops below about 0.35ms - very few injectors that I have tested will open with only 0.3ms so I would say either all or some of your injectors arent opening sometimes in these conditions.

Try setting the minimum effective PW to about 0.4ms to see if that solves it.