Audi 100 / A6 idle / deceleration problem

[wysiwyg73]

I have run my 1994 Audi 100 (A6) 2.6 V6 (ABC engine) for 10 years with virtually no major problems, but a while ago it started having intermittent running problems. When warm it often won't idle at less than 1100rpm, sometimes as high as 1400rpm. From cold, sometimes it just cuts out and I have to restart, keep the revs up and drive until it gets some heat into it. I can cope with these instances, but there is an associated problem when I decelerate - there is a time lag which means the power is still on after I've lifted the throttle. This makes the car jerk as it comes off suddenly and this erratic behaviour is not pleasant in traffic.

I have had the car tested by a local garage and they say nothing shows up on a diagnostic check. They seem to think that it is a problem associated with the throttle body and after they cleaned this the car ran well for a whole week! The problem then returned. I am not convinced that a repeat clean will cure the problem and feel that they may have just accidentally effected a temporary cure by carrying out the work.

Any ideas / comments would be much appreciated.

[adamss24]

Hi, take the battery off and clear the static by turning the lights on. Then reconect and take car for a drive while the ecu adjusts itself back to optimum settings. Make shure to drive in trafic as well as on the motorway for a while. Remember that radio code. Also check any vacuum hoses for splits and do a scan for any fault codes and see if any Coolant Temperature Sensor faults do show up. If they do, check the wiring and replace as its verry cheap.

[wysiwyg73]

Thanks for the suggestion. I note what you say about disconnecting the battery and it costs nothing to try it. I don't understand why the car ran okay for two weeks after the throttle body was cleaned and then suddenly reverted to the same fault when nothing had been done to it.

The temp sensor was tested and is deemed to be okay - could be an intermittent on the wiring. I'll check that and other sensor connections.

Maybe it's just age..... it's done 244k, runs well (apart from this issue), is reliable and still cruises at a speed that you don't want the law to know about!

Thanks once again.