Refusing to Idle

[Random24234]

The Cerb freshly back from its last vacation to a garage (MOT + Service + a few bits and bobs) has developed a new issue, it refuses to idle when hot and now after a lovely trip down to Poole Quay, it refuses to idle at all (just stalls). I first noticed this when i drove back from the garage but I assumed this was due to being ridiculously brave with a empty tank, But after today and still quarter of a tank left, i feel this is not it. On the quay it idled fine, popped it in gear and set off home and it was worse then ever.

The best description is when you lift the clutch up and take your foot off the accelerator, the engine should just drop down to the idle i think about 1175 when warm? Mine just stalls. If you let the engine with the clutch in brake down to 1200-1400 rpm then hold the clutch out it most of time will idle, any higher rpm it will stall.

I tried this at various different speeds on the way back and reversing into my garage was a nightmare not being able to idle, making every gear change a engine start up.

Can anyone think of any simple things that might cause a car to refuse to idle. Or it would seem run below 2k rpm happily. I'm clutching at straws but i was wondering if it might be the pots feeding the ecu incorrect data and thus flooding the engine. Any other ideas? I'll be phoning the garage on Saturday but my hope is i might be able to fix this myself.

Edited by Random24234 on Friday 28th June 21:51

[C3BER]

Throttle potentiometers would be my guess and its a guess.

[Gazzab]

Did garage reset adaptives.. . .? Might need to relearn?

[C3BER]

Give it a blast down the motorway and get it hooked up.

[pmessling]

lamdba i'll guess at, although you would think your mill would come on?

[Jhonno]

Airleak?

[C3BER]

Could even be iffy leads which makes it not a simple find unless you plug it in. I know as i have just had a lambda fault... Mil on and runs crap.

[Cockey]

Sounds quite similar to this

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[P S K]

Have you checked the idle screw?

Could be as simple as that.

[Tanguero]

P S K said:

Have you checked the idle screw?

Could be as simple as that.

This would be the first (and simplest) thing to check.

[Random24234]

I've checked the idle screw, it was my first port of call. She when it was behaving, will idle perfectly starting cold at 950-900 ish and warms up to 1150-1200 (so hard to tell without plugging into the ecu). There's no MIL lights or warning lights, the oil pressure sits where roughly you might expect and the car was recently serviced so i'm hoping its not an air leak. Generally over 2k she drives like a dream the more i think about it, the more its flooding itself with a high throttle pot reading seems likely.

Cockey's thread describes exactly the issue i'm having, alas there is no stepper motor that i'm aware of on a 4.5 AJP, so the solution is not quite that.

A phone call to the garage and they suspect what i do, a throttle pot has died and they will pick her up on Wednesday so we shall see what happens then. Saves me the hassle of faffing around with a laptop i guess, something i was not looking forward to as a laptop it belongs in a museum with a battery life measured in minutes.

[C3BER]

Looks like my guess is correct

It's funny how these things sneak up on you. One minute everything is fine and then its just not quite right and then the it's like driving a fairground ride.

[Jimbolian]

Just replaced coils, leads, plugs and mine has the opposite issue.. only idles at 2k no matter what i do with the throttle screw, unless i wind it right in in which case she'll start and cough out again.

At best she will start and idle at 1100ish.. but then rise to 2k on it's own.

[ridds]

My money's on throttle pots/bladed jot being set correctly unfortunately.

I'd send it back to the servicing garage and ask then to do the job properly.

[Warwick67]

If it was fine before you took it in to the garage, take it back......