Zooter

I've been getting the occasional case of my 1.8T stumbling bably on cold starts. It sounds like its running on three cylinders and unburned fuel can be readily smelled. This condition usually clears up after about 30 seconds of idling or so. I told my dealer and he suggested it was a simple case of the fuel not vaporizing properly in the cold weather. I then mentioned that my Honda exhibits no such condition during identical cold starts. Then he mumbled something about high octane fuel and blah blah blah....have any of you other guys/gals experienced this problem? I thought it might be something spark related and am a little concerned my dealer doesn't even care to take a look. It is a '99.5 and completely stock.

Perpetual Novice

There is a theory circulating among techs that high octane RFG (reformulated Gasoline, wheat you get in a major city) doesn't vaporize as well, causing the rough stumble. One tech even recommended to switch to 89 octane to see if the problem went away.

If you haven't cleaned your injectors in a while, do so (Have the dealer do it) If the problem doesn't go away, I'd suggest running 89 octane + octane boost for a tank to see if it improves things.

'Bahn Burner

..Both my GF & my 1.8T's had this problem. It has to do with the low compression ratio of our engines. We used Mobil & switched to Sunoco and haven't had a problem since. Try not using the highest grade octane either, Sunoco offers a 93 octane, right below its Super grade octane of 94. I believe Audi recommends 91 octane for the 1.8T, but when the dealer first diagnosed our problem they told us to use 87 grade fuel. AFAIK putting 87-89 octane doesn't do any damage, but it does perhaps, rob the engine of power due to detonation.