Lumpy Idle on Audi 80

Posted: Wed May 14, 2003 6:38 am

My Audi has recently been idling badly and starting badly. 1991 AAD 2.0 8v. I have just read the posts regarding Lambda probes and definitely need to do that job as i know mine has not been looked at for AT LEAST 140,000 miles!
Will replaceing this cure the lumpy idle and poor starting? (When you start the car from cold it will run but as soon as you give it any throttle is pops and stutters and even stalls. This goes away completely when warm - still lumpy idle though.)

P.S. Fuel consumption is approx 30mpg, all motorway miles

Any random thoughts welcome.

Cheers,

Steve.

Site Moderator Joined: Jan 31, 2003 Posts: 9144

Unlikely a lambda probe will help cold running - until the probe has been warmed up, the ecu ignores it. Common symptoms are heavy fuel consumption and or poor acceleration once warm

I would suggest either a vacuum leak or possibly fuel injector problems. Most common is the crankcase breather hoses leaking. For injectors it will be either seals or the injectors themselves leaking.

Inexperienced Joined: Jun 27, 2003 Posts: 33 Location: UK

I had this problem on my 80`89 1.8s. turned out to be the carburrator flange had a hairline split in it.
You can check this by starting up, allowing the engine to idle and pushing the air-pan, gently but firmly from side-to-side and up and down. The engine will begin to stall or you may hear a sucking sound if this is your problem.

The part is cheap and easy to replace.

UltraUser Joined: Jan 21, 2003 Posts: 4230

Alternatively on fuel injected cars spray WD40 around the inlet manifold/plenum chamber and watch the exhaust for smoking, this will confirm an air leak. Fuel injector cleaner may help provided the injector seals are ok. Evil or Very Mad