I have a 2000 A6 2.7 6 speed with just over 105k miles. It's a sport pkg. car I thought would be fun to "expand the capabilities" of. The problem is that it has a rough, low(500rpm) idle after warmup and will typically pull random misfire codes for the right bank, cyls.4, 5 & 6. I'm about out of things to change out. I've had all the injectors and coils swapped and checked, fresh plugs, new maf, new front left bank O2 sensor, checked hoses for leaks, & yesterday a new throttlebody...it still does it. I've occasionally had the EPC light come on at startup and, after shutting down and restarting, it's gone. The code that came up after that was a 1558/throttle actuator electrical malfunction, hence the throttlebody replacement. The timing belt was replaced at a reputable dealer 15k ago. It runs great, excellent mileage and very good boost...it just won't idle for crap. Any ideas? I'm runnin' out of money here!

 

After a throttle body replacement an adaptation is necessary (I believe).

Or drive like that for while, the ECU should take care of it.

What is your current situation?

Any changes?

 

do a TBA. Also it could be your coil pack amplifier for that side. Switch them to see f the misfires change side too.

 

do a TBA. Also it could be your coil pack amplifier for that side. Switch them to see f the misfires change side too.

 

run some seafoam in there!

 

Thanks for the input!
The new throttle body has been in for a week so it should be adapted by now...nothing, it runs as weak at idle as before. That's the weird part. Other than low idle the car is strong as any I've ever driven. If I manually keep the idle around 800-1000 at a stop light I never get any cel's.
As for the coils, I've switched them all around and did the same with the injectors...still get a low idle. By the way, I'm not a tech so what is a TBA and how do I check the coil pack amplifier for 4,5,6 side?
I also ran BG to make sure carbon buildup wasn't a factor. When the coils and injectors were switched around they told me the MAF was reading low. How can that happen when it's less than 4 months old. This is driving me nuts!

 

Anyone know if a 2000 would be drive-by-cable? If so, I think you have to Vag-Com the Throttle Body Adaptation (TBA). Only the drive-by-wire (electronic) throttled cars do it automatically. I've also heard that with drive-by-wire you can get an adaptation by leaving the drivers door and hood open, and turning the key to on without starting the car for 30 seconds. You should hear the throttle body moving if you lean in close to it.

 

My 2000 is electric. I have a 98 A4 2.8 that is cable, but the throttle body adaptation works on that too (door open, hood up, key on).

To check the coil primary stages, there is a quick test: Lift the plastic cover on top of the airbox, you will see primary stages there. Remove the four connectors (2 black, 2 tan) and plug them back into the opposite primary stages and see if the misfire has moved to other side. Tan plugs = 4,5,6 bank, black = 1,2,3.

If you are handy with a meter, there is a definitive way to check - search for a thread on testing the primary stages.

 

bump - i hope you find your answer, i'm curious to what it is.

 

Okay, did the TBA...nada. Kinda figured that when the car ran exactly the same after the TB swap. I switched the black and tans like you said loach1 and got the same dang reading:P0300 (rand. misfire) P0304 & P035 (cyls. 4&5). When it starts it idles perfectly, but by the second stop light it's idling around 550 again. All the filters are new, I run premium fuel only, and I really don't want to push it over a cliff (it's getting tempting, though).