QuestionQUESTION: My engine has always ran perfectly,
However suddenly there is a problem,
Engine idles perfectly at 600 RPM in park,
But when you engage drive,
Revs keep dropping to around 300 then 600,
Constantly reving up and down,
Car runs perfectly in every other respect,
I haven't had a vagcom test done yet,
Maybe faulty MAF,
I have changed my fuel recently to bp ultimate ?
Any help would be appreciated.
ANSWER: Could be MAF but I would check idle control valve first. Don't think fuel change will have an effect, could be a torque converter issue too. Does the car surge when you release the brake and let it go? Accelerates smoothly still?
Let me know, Jan
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QUESTION: Thanks for the quick answer jan,
Car accelerates smoothly no problems,
But rev`s constantly going up and down as described,
When vehicle in drive or reverse,
Car still does this when i release the footbrake,
Howevever touching the throttle stops the problem !
Strange thing is its Idling perfectly in park or neutral ?
ANSWER: The slight increase in load is causing a change in the mixture requirement, and it sounds like this is not being adjusted correctly. I would get a VAG-COM and see if there are any codes, also check if the throttle microswitch is audibly clicking when the throttle is closed, and check if the TPS (Throttle position sensor) is functional. Let me know, Jan
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QUESTION: Thanks Jan,
My friend has told me to get rid of the Audi and by a focus,
Problem is i love audi cars and appreciate the build quality,
However this problem is not now endearing me to this car,
Anyhow,
I know it probably isn't but i am going to fit a brand new high capacity battery & replace the six spark plugs with brand new ngk dual anode plugs,
Then i am going to run fuel down so warning light comes on,
Then i am going to refill with ron 95 unleaded,
Run the car for around 15 miles,
If no better i will then book the car in for vagcom diagnostics,
I was not aware that their was a throttle microswitch,
And i am not aware of hearing anything either,
Is the micro switch on the throttle body ?
I will have a look as soon as its light enough,
I have an 80s superbike that had a TPS problem,
I solved that by stripping cleaning and re-adjusting,
I wonder if this may be the problem,
I still keep thinking MAF faulty (Dont know why)
Thanks for your help & i will keep you informed,
PS/ I forgot to mention that when i turn the air conditioning compressor on the car idles normally ??
I am only joking when i say this but dont tell me to drive around with the air conditioning compressor on,
Its winter you know.
Regards
TJ
AnswerA FOCUS??? Give me a break! Fix Or Repair Daily is what I say to that! There is no beating German technology. While the things you suggest might improve the running somewhat, these will not fix your problem. You need to establish which component has failed, and replace it. It could be the MAF, but the MAF is not really part of the equation when the car is at idle. The idle control valve determines the idle mixture. Also the PCV valve and EGR systems can have an effect. A VAG-COM will probably give you a faster indication as to what the problem is, and will help you to identify the correct cause. Let me know, Jan
