Weird symptom - occassional pause / stumbling?
 

Hi all,

I've had the car (01 a6 2.7t mt6 93k miles) for about a month and driven it for about 1,000 miles. I've had this happen about 10 times, and 9/10 times it was in slush or snow. It only seems to happen when I'm at a constant speed, barely touching the gas, usually around 1500 rpms, and usually in the snow/slush. It feels like a slight engine breaking, or maybe like the car is cutting off ignition for half a second, or possibly like the brakes engaged for a 1/2 second.

At first, I was fairly convinced this was my imagination (hitting a small bump or something), then I was fairly convinced that it was me letting off the gas and getting a little engine breaking, but I don't think that's the case. Maybe the stability control system or the abs doesn't like the snow and is going a little haywire?

When I brought the car in for a TB change, I was told there was a CEL for a bad cat. conv. on the driver side and some other emissions control thing was bad. The CELs haven't come back since he cleared them and there are no other CELs right now.

Thoughts?

Brian

Weird
 

Hi,

It cold be the stability program engaging if its sensing wheels spin. Have you ever noticed you, "ESP" light illuminate on the instrument cluster when you experience this?

No, I haven't noticed it. I'll keep a look out for it next time it happens.

2000 A6 Avant with 130K miles.

I've had the same thing happen. Recently I can recall it was in snow/slush. I can't remember if it ever happened on dry roads though. Although it wouldn't be stability control if on dry roads. I've had the concern it was the transmission but what you've described here is exactly what mine is doing. I did have the timing belt replaced 25k miles ago and started thinking maybe the engine was missing or something. I could never really put my finger on whether this was an engine or transmission thing. I had the tranny fluid replaced by mechanic.

I'm hoping when we get out of this winter weather it doesn't happen on dry roads as this would confirm it's either the tranny going out or possibly a engine/timing issue?

Yeah, I'm hoping its not the engine or the trans too. I have had it happen on dry roads one time, but I still expect that the check engine light would go off if it was misfiring. Mine has a manual transmission, so I don't think that would be the issue in my case.

I vote for stability system engaging. I do not have it in my 00, but or 3 series has it, and when it engages, it can feel like what you describe.

I had the same thing happen to me last night. No ESP light and no sound from the brakes. It was on a straight road but the road was slick with snow.

I had it happen to me a few weeks back but then it went away. Again, cold snowy weather.

No codes. No CEL. No ESP.

Bob

I believe there are two systems, ABS and ESP, that work together. When the ABS system actively engages the brakes to prevent a skid, the ABS light goes on. I don't recall seeing a separate ESP light.

I do know that when I force a slide in slush or deep snow, I can feel the brakes try to counter the slide and the ABS light flashes briefly.

Ok. Sounds like the ESP might be being a little oversensitive. Hopefully its nothing else; I'll watch out for any non-ESP related symptoms.

Thanks for all of the responses.

Brian