Car stalling on clutch-in after high RPM run

[andrewbr]

So my car has started stalling when I push in the clutch immediately after running at higher RPM, such as from a high(er) acceleration run to slow down for a turn. The revs drop too far, almost like the stepper can't react fast enough to "catch" it. As far as I can tell this only happens when the engine is hot but I don't push it before it's warmed up so I can't say for certain.

It seems to run completely fine in all other situations - cold, hot, just cruising around at normal speeds, in traffic, etc. In normal driving when I stop and push in the clutch I see the RPM drop to around 750 but it jumps back up to about 1000 right away. Seems normal to me.

Today to attempt to diagnose it I checked all the vacuum hoses in the engine bay, no obvious leaks or noises. The stepper motor was recently cleaned and seems to be sealed properly.

I've also recently adjusted the base idle down a ways which helped the car's in-traffic behavior; as a result of this issue I backed the screw out a half-turn, but no change.

Any ideas of other things I can check? It doesn't seem to be an ignition-related issue as the car runs fine in traffic when hot, and after it stalls I can immediately restart it without any hesitation.

Thanks

[Marc p]

If the vacuum lines and ICV are definitely 100%, then my initial guesses would be a sticky throttle body (If it’s not closing fast enough, it could cause the engine to lean out enough to stall) or the clutch isn’t completely disengaging, quick test is usually to put the car in first with your foot on the clutch and give it some revs, if the car try’s to move forward, then it’s not fully disengaging.

[Belle427]

Sounds more like a lack of air with the throttle plate closing quickly but i cant explain why.
Maybe re visit the base idle setting back to factory first but you seem to have done this.
Checking the basics such as throttle pot voltages is a good place to start.
Info midway down the page here.
http://g33.co.uk/pages/technical-fuel-injection.ht...

[andrewbr]

Thanks both for the suggestions. I reset the base idle which seems to have done the trick. My working theory is that I previously set the base idle while there was an air leak somewhere, and in hunting for one I must've inadvertently fixed something which caused the engine to be starved for air in the situation I described above. Lesson learned and future note to anyone else with a similar problem. At least it was an easy fix and now I can go on to all the other things I need to fix on the car

[Belle427]

The simple fixes are always the best ones.