Rough idle

[deanb34]

1991 230ce idles low and lumpy, most of the time it goes up and down at about 7-8, but sometimes its 6-9. its had new plugs and leads, rotary idle. Any ideas ?

 

[brandwooddixon]

Does the car run OK in all other regards?
Now that you've had it running for a bit, what colour are the spark plugs? Do they look fouled?
If your car is an automatic does it idle worse when in gear or in nuetral?

 

[deanb34]

I have not looked at the plugs yet, but will do so A.S.A.P, yes it does idle a bit slower in drive but not much about 6-7. When driving, the car runes ok, but when you accelerate hard it feels like it’s surging slightly but sill pulling.

 

[deanb34]

the plugs look ok

 

[horgantrevor]

it may also be the cat as the lamda sensor is their and if the cat was gone the back pressure would be wrong and the car would be jumpy at idle a litttle

 

[deanb34]

How do I know if my car should have one or not?

 

[horgantrevor]

check on web site she has i think but make sure the exhaust has a lot to do with a car and if she is a 91 its well due a change

 

[deanb34]

After lots of messing about the car is running a lot smoother now, but sometimes will still not idle, any idlers?

 

[deanb34]

Could I have a dodgy sensor, if so which one should I be looking at and how do I test it?

 

[bigasotonuk]

Hi,
If the the idle is still erratic try cleaning the the throttle control valve this cured my idling problem.

 

[deanb34]

Thanks, I shall give it a try

 

[deanb34]

Where will I find the throttle control valve?

 

[GarryO]

Its under the airbox / air filter thingy. Get yourself a workshop manual, and at the very least you will be able to identify your cars components. Got a very similar problem on my car, and I think Ive sorted it with a 5 pound can of carb and injector cleaner.
Have a look at my thread "erratic idling"
Best of luck

 

[GMK]

Does it only get lumpy when the engine has been running a while? any pinking under acceleration? Could be a timing issue if there are other symptoms