Hey guys as title really, bought a 04 a3 in may with 126k miles onit with fsh, running fine , pulls great in every gear. recently every now and again it'll rev at 1100rpm instead of 850ish? If I switch engine off it'll go back to normal when started, happens when engine temperature is at 0 or 90 ? Any ideas? Thanks Gary
2.0tdi bkd intermittent high idle?
- Thread starter Gary-92
- Start date
Is it not just because your engine fans have started?? This can cause more load on the battery so the engine picks up the revs. Is the needle steady at 1100 or does it jump between 800-1100 irratically?
Is it all of the time or only when you have lights air con etc on and stationary or after heavy driving? Sounds to me like there is nothing to worry about and simply the engine putting load on automatically, if you notice any dramatic changes or it does it constantly it maybe worth having the battery checked or even a dodgy alternator..I have uncovered most of the 2.0 tdi faults and niggles on mine so I can advise from personal experience lol. Hope this helps
Not all of the time just randomly , like this morning it was cold and only drove like half a mile and it did it, where as yesterday was same and it didn't so it atall. On Saturday night I went in to my local town to drive round in circles haha.. Was in for half an hour then It started doing it, switched of, jumped in with one of my fitness came back maybe 2 hours later, drove for an hour and was fine? It's weird gaha
Try and keep an eye on it over the coming weeks to see if it starts to do it more often. If you find that is starting to become a regular thing have the alternator checked as the clutch pulley maybe on its way out. It can start to slip causing a surge in the engine. If you catch it early enough it is simply a case of changing the pulley, if it becomes irratic the the bushes in the alternator can go meaning to replace the whole thing, this is how mine started then after leaving it for a month or too, the idle started to become rough. I ran it through vag com with no prevale so I checked the voltage on the battery and it fluctuated between 12-15 volts on idle. It turned out to be a fault on the clutch pulley. After I changed it everything was fine then out of the blue it started again. I changed the alternator out and ever since then she purrs.....well like a tractor but at a steady 850 rpm. If you have a voltmeter check the current coming out of the battery while the engine is running, you will be looking for a steady flow of current. Any significant current changes can point to the alternator being faulty... let me know how you get on mate
I have a multi meter so will check tomorrow at lunch mate. It's 14 something with engine running isn't it? Or is that petrol engine? I will update tomorrow . Thanks for the replys
Update, with engine on it was giving me 14.11 to 14.14. I presume that works out at 14.1v to 14.4v? Thanks
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Yeah that's pretty much spot on as the alternator charges the battery by delivering slightly more current back in then the battery produces otherwise it wouldn't charge the battery. There is loads of idling issues with the bkd engine but I would say yours is fine. If there is any major changes just drop me a message and I will try to help some more
Thanks for your help mate!! Will keep you updated.. It's getting motd start of December, paint and major service in January!! Money money haha
Awsome hahaa bought mine with full 2012 front end, s3 breaks, s5 interior. Black edition grill and wheels and drl to. I like it haha
Resurrecting an ancient thread I know but wanted to mention my experience...
I did the cam belt on my BKD a few months ago and realised that the alternator freewheel clutch pulley had seized so purchased a new INA item and made a note to replace it when I got the chance…..
When I came to fit the new pulley I found that despite using the correct tool and splined bit the alternator spindle stripped out , so couldn’t get the old pulley off……
This led me to buy a replacement alternator but time prevented me from changing it over.
Recently I began to get intermittent high idle, it would regularly (& randomly) reach about 1K rpm when at rest , it did this engine hot or cold and would also do this with the air-con turned off.
Looking on the internet, there were suggestions that a bad alternator clutch pulley could cause an erratic idle speed , but the fact that turning the engine off and immediately starting it again would cause the idle speed to return to the normal 750-800 rpm seemed to suggest that it was an electrical issue.
I finally got around to fitting the replacement alternator & pulley a few days ago and it was then that I found that the original alternator was on its last legs.
The spindle was running out of true and can only assume that it was not producing enough power, causing the ECU to raise rpm to compensate.
There had been no dash warning lights or untoward noises.
This has cured the high idle speed completely now.
Hope this info might help others.
I did the cam belt on my BKD a few months ago and realised that the alternator freewheel clutch pulley had seized so purchased a new INA item and made a note to replace it when I got the chance…..
When I came to fit the new pulley I found that despite using the correct tool and splined bit the alternator spindle stripped out , so couldn’t get the old pulley off……
This led me to buy a replacement alternator but time prevented me from changing it over.
Recently I began to get intermittent high idle, it would regularly (& randomly) reach about 1K rpm when at rest , it did this engine hot or cold and would also do this with the air-con turned off.
Looking on the internet, there were suggestions that a bad alternator clutch pulley could cause an erratic idle speed , but the fact that turning the engine off and immediately starting it again would cause the idle speed to return to the normal 750-800 rpm seemed to suggest that it was an electrical issue.
I finally got around to fitting the replacement alternator & pulley a few days ago and it was then that I found that the original alternator was on its last legs.
The spindle was running out of true and can only assume that it was not producing enough power, causing the ECU to raise rpm to compensate.
There had been no dash warning lights or untoward noises.
This has cured the high idle speed completely now.
Hope this info might help others.
