Hi, for two weeks I have had poor idle conditions, on higher rpm s, it runs fine and has the power there. One could compare the symphtoms similar as having choke on in old cars with 1000 rmp which accasionally starts ramping up to 1500 and jumping down back to 1000 as if ECU is trying to find an operating point.
Sofar I've checked: no codes from A2 nor A6, running temperature ok-all vacum lines going out from the distribution tower are ok, carburrator body is clean with two holes in the bottom open, flame trap is clean, spark plugs are in fine condition-idle air control valve gives small vibrating feeling with power on. Regulated gas pressure shows 2.8-2.9 bars and is regulating fine, checked most electrical connectors accessible.
Renewed later the distributor cap, rotor, spark plugs and air filter. Had a MAF, IAC and HT lead swap without change and cleaned fuel injectors.
Ran mode3 tests in A2 and A6 –no codes but bad idle stays,
So it was time to go back to the basics and start searching the unexpected and found a leak in 1st cylinder air inlet manifold casket not visible nor to hear, but the idle made immediate difference when spraying soap water around the joint.
So I renewed yesterday the gasket and cleaned/renewed what I found below the inlet manifold and the car is running so nicely again. Thanks for all helping me out to carry on, I hope you some time can benefit from this experience I had.
;o) tapsa