RPM fluctuation ??
 

So it usually happens when i first start to drive the car. Around 35-40 mph when i am trying to hold the speed constant the rpm's will jump up and down 1k its usually when they are around 1600-1800 rpms. Not sure if that is just the turbo or what. It becomes really annoying because the engine is revving back and forth as it goes up and down rapidly. just bought the car last week 2008 A4 CPO 2.0. Any one have any ideas?

A little over a year ago, I purchased a 2005.5 A4 that exhibits the exact same problem. I brought it in to a local independent garage that's known for their expertise with Audis, and no one was able to find anything serious.

Over the course of the last year, I've noticed a few things - this fluctuation is a lot worse in cold weather, and after the car's been running for a while, it dissipates entirely. I encounter it at the same exact speeds you are - it's most noticeable between 40 and 45mph.

If you dig around these forums, you'll find other references to the same symptoms, though I don't think a definitive cause was ever identified. Since my computer, transmission and engine all check out fine at service, I've chosen to just chalk this up as one of my car's "lovable quirks." If you ever stumble upon the culprit for this flux, please be sure to post it!

Hmm yeah today it was alot warmer then it has been in the past and I didnt seem to run into the problem at all. Weird, oh well. I feel a lot better knowing my engine isn't about to explode. knock on wood

PCV or diverter valve. READ MY faq FOR REPLACEMENT SUGGESTIONS.

Abetz:

Mine does the same thing, and has for most all the time I've owned it (2006 A4 2.0T with 136,000 miles, I put on all but 24,000 of those miles.). Does go away once car is fully warmed up. Doesn't seem to be doing any harm. I plan on checking the diverter valve.

"PCV or diverter valve. READ MY faq FOR REPLACEMENT SUGGESTIONS"

Where can I find this? Sure is much easier following instructions, and my wife says I always need instructions.

Any help you can give will be appreciated

It's one of the stickies at the top of this forum: https://www.audiforums.com/forum/sho...d.php?t=144534

I'm not sure if there are specific instructions in there, but you should be able to find it by either searching or googling "audi pcv replacement" or something like that.

See stickey up top. Having a 2008 you probably have the best diverter valve but it can be checked by pulling it off and putting it back on i half hour. You want to make sure you have the piston version and nor one with a diaphram in it that can tear.

Probably the PCV which they keep updaating but never seem to get a proper version that fixes it. If you have warranty they will fix iy. I recommend the BSH brand which is practically bullet proof and have never heard of a failure. Lots of good info in the FAQ up top.

Will your not alone. I have a 2000 Audi A6 Q and I too had the RPM fluctuation issue but mine got progressively worse. I'm not saying you have the same problem but it turned out to be a transmission problem for me. There were warn parts that needed replacing. Cost me $2700 to fix (parts + Lab). Found it hard to spend that dow but I love the car and plan on keeping it another few years. Rides nice now. No more RPM fluctuation. I would have a trusted transmission place run a diagnostic and test ride.

any new updates on this mysterious problem? At first I thought it was the trans, but now its just reving in the morning and goes away after about 5 miles. :confused: