SpeedAgent

Guys,

I was on flat highway this evening probably going 70mph and the engine was plenty warm. I had been driving for at least 20 minutes and the ambient temp was 60 degrees F. I was driving in D and was no putting the car under any undue load, just cruising in traffic when all of the sudden the car started to feel like it was decelerating then jerking accelerating and the tach needle was jumping from 1500 to 2500 back to 1500 and back and forth back and forth for about 10 seconds. It felt like I was hitting the throttle and brake alternating each. It stopped after 10 seconds, but what the hell is going on? I bought this a couple of months ago from a dealer and I found the former owner here on the forum. He said all of the TSB's were taken care of. Knowing this what do you guys suspect here? I'm a little nervous since this is absolutely not the normal hesitation of the 1st gear issues. This is clearly something else and potentially serious.

Any advice is appreciated.

Chris

am_ver

My guess is that your Torque converter is on its way out.

KevinGary

You did not post the year or the miles. You should consider changing the ATF.

SpeedAgent

44k on a 2007. Torque Converter already?

SpeedAgent

Update- spoke to the service person the previous owner worked with (she is familiar with this exact car) and she said it sounds like a faulty brake light switch. She also said they have rarely seen a torque converter replaced and she has been there a long time.

Have you guys heard of a faulty brake light switch causing these problems? She said that it would throw a code and it would also cause the car to lose torque and would affect how the torque converter worked. I know cars, but I don't know this.

also, it would appear that if this is the case that it is easily replaced DIY. The part is $14, but the Audi labor is $175. It looks like it just goes in under the dash?

Chris

misterjj2u

I doubt a faulty brake light switch would cause your car to do what you described your car doing (which, btw, sounds like an engine misfire / coilpack issue / tranny issue than anything else).

Are you covered under CPO?

A brake light switch should NOT cost $175 in labor to do. If it's anything like the B6 platform, you literally twist the piece to remove it and twist it back on to install it. Maybe just buy the part and get a local buddy to help you out.

Lastly, do you have a VAG Com? That way you can scan the car for codes (i.e. misfire?) and actually see what the issue is.

I rarely trust what service advisors tell you at the dealership. They make most of their money from service and repairs.

SpeedAgent

Could a faulty brake light switch cause a traction control issue? Could I have been experiencing traction control engaging?

misterjj2u

I don't think so.

Honestly, your best bet is to get your car scanned for codes (try an Autozone). Write down the code values and descriptions and come back.

Or find someone local with a CAN-BUS vag come to scan your car for you to see what error codes were actually triggered.

SpeedAgent

Hopefully doing this with the former owner who has a VAG COM in the next couple of days. It hasn't happened again and the car isn't making any strange noises. Weird.

2008A6

It's not too far fetched considering that simultaneous braking releases throttle on our cars. So weired things can happen if the electronics are sensing braking signals.
VAGCOM should provide you with better answers.