car stalling at lights when warm

[Chimp871]

my wife is not happy with me or my car!

Car runs fine, and at junctions when warming up also no problem.

But when up to temp (oil and water) and you stop at junctions/lights the engine 'hunts' it goes down to very low levels e.g. 500 rpm then races up to 2k, repeats and then typically dies due to no revs.

Before I start the search on sensors, stepper motor, vacuum leak - has anyone gone through this before and had some typical areas to look into.

[Chimp871]

ECU fault code list on rovergauge showed several faults. I've logged it but can't find the file!

I recently changed my lambdas and they were flagged.

I cleared the codes and went for a drive and when I got back I changed the stepper motor steps via software and this (obviously) stalled the engine and threw a fault code.

So far - with the codes reset it seems to idle at warm nicely, if it throws another fault code I'll swap out the stepper motor. I recently bought 2 x used (but good) stepper motors from Jools as he collects them from ECU upgrades.

My engine is also historically run rich causing MOT issues. But step-by-step.....

[Chimp871]

regularly - it may have been the fault codes and the reset fixed it. But i'll take it for a spin tonight and see if it repeats, if it does I'll try another stepper motor and go from there.

[Chimp871]

Bought my sensors from tvrssw around that price. Didn’t search for the ntk logo but assume they’d only sell reputable and suitable parts.

[Chimp871]

al5x said:

Mine does something very similar too (revs flaring/stalling etc.) it drove me crazy and I ended up not driving it also similar to the issues reported by Dan here https://www.pistonheads.com/gassing/topic.asp?h=0&... when left on the drive to warm up.

My current plan is just to go with an emerald/canems/whatever when I can afford to, otherwise I'm worried I'll just end up chasing problems/parts and never being able to enjoy it properly.

it can be frustrating but it's worth working your way through the problems as if you have a vacuum leak, faulty sensors a new ecu will not fix them. Methodically use rovergauge results (post the logs on here, you'll get advice), then without buying parts and parts just by process of elimination. Stay with it rather than just spending over £2k.

[Chimp871]

No one disagrees. But there’s a practicality between new ecu and specialist expert.

It’s good and healthy to attempt to self diagnose otherwise we’d never get under the bonnet. As a fern owner too I admire the chimp community for delving deep.

[Chimp871]

So the reset of the fault codes has appeared to fixed the problem, not perfect but a lot better and it only drops to low revs then spike at start up in warm up. But once you blip the throttle it seems to settle.

Others experts will have to tell me clear in daily codes makes any sense or not but time will tell.

I’ll try another stepper motor just to see if the SM is the root cause.