So I just got my car fixed after almost 2 weeks of electrical problems and today when I've been driving it, the idle has been rough. I'm not sure what's going on but I did have the battery unplugged for awhile. It idles between about 600 - 1000rpms and the needle just bounces up and down. I've got a vagcom but haven't had the chance to get it out yet. Does anyone have any idea what could be causing this? Thanks in advance.

 

i had a rough idle problem on my 2000 b5 a4. turns out the throttle body needed cleaning. the guy i took it to said it needed a new ECU. bullshit. cleaned the throttle body and we're all good now:]

 

Wait...I failed to mention that I've got a 98TQM, so I'm a member of the B5 club as well. I don't have my repair manual handy, but I'd assume that it would tell how to clean a throttle body?

 

Damn man. You can't catch a break. Below are some quotes from Jestnomen concerning erratic idle problem in another post.

Jestnomen wrote:

I would reset the ECU and perform a throttle body adaption if i were you. Disconnect the battery for 30 minutes or so. Turn the car on to the position just before starting. Let the car sit like this for 4 minutes or so. You should hear some clicking from the engine bay as the throttle body adapts. Make sure you have your radio theft code too.

There is a stepper motor that actuates the butterfly valve in the throttle body. On the non drive by wire the stepper motor only corrects the movement to establish a controlled idle. On the drive by wire cars it controls all movement from idle to wide open throttle (WOT). Typically rough idles are caused by the throttle body needing to relearn the settings for a smooth idle. This is also called an adaptation or throttle body adaptation (TBA). Readings from MAF are calculated in determining the correct idle speed. Thus if a new MAF is installed it is conceivable that the engine could idle erratic as is the case here.

 

Aaahhhhhh....thanks a lot buddy. I'll disconnect my battery again when I get a chance. Hopefully that'll fix the problem so I don't have to do any more digging. But you're right...I can't seem to catch a break. I've had the car for exactly one year now and the amount of stuff that's gone bad is amazing. No wonder these cars lose their resale value. If any newbies are reading this, my advice is to learn how to do everything yourself and you'll save ssssoooooooo much $$$$. I still love her though.

 

i did a TBA after getting GIAC and it smoothed things out all around, unless it was just the placebo effect, it is DBW. Were older Audi's say a 1988 Audi 5000s able to do TBA's? I remember the dealer telling my dad when he had that car to turn the ignition on and wait a few mins before starting if the car ever performs badly. I remember loving that car! For a 5 cyl it was quick and had the same center arm rest design/power locks and funky warning lights and stuff. When I was a SUPER NOOB I put rubbing alchohol in the crank case thinking it would clean it, ended up F-ing the hydrolic oil lifters hahaha.. My dad never new that ****. Sorry to get off topic. But yea TBA is worth a shot for sure.

 

That's funny. I'm getting my GIAC chip the week before Christmas [Merry Christmas to myself] and I want to make sure everything is running right before I do that so I can feel the full effect. I can't wait.

This is just a wild guess but I'm assuming TBA = Throttle Body Adjustment in which the procedure described above?

Thanks everyone for your help.

 

Yeah adjustment/alignment/whatever... Youll love the GIAC! Just make sure that any fault codes that appear after being chipped are erased, and then get it scanned again in about a week to make sure everything is cool. I had a bunch of fault codes after being chipped, and found out that when my ecu was removed to get bench flashed it will get some fault codes, you just need to clear them when the ecu is back in the car. The douche that flashed my ecu obviously wasnt aware of this, I found this out directly from GIAC.

 

Huh...thanks for the tip man. I'll be sure to take my vag-com with me on my holiday vacation. Never leave home without it, right?

 

Dont know if it's the same for 1.8T's but i had the same problem and a cleaning/polishing of the throttle body myslef helped, but mostly the difference was made by cleaning out the ICV, or idle control valve. I followed a DIY from (i think) audiworld.com or there might be one here dunno. but try that too.