I don't know if anyone else has experienced this issue before, but I have noticed that when I start the car, then put it in drive and start rolling, the car vibrates violently for about a second as if it's about to stall, then clears up. I'd say that this happens about 10 - 15% of the time. The engine doesn't throw any codes and the scan results show nothing -- could it be a coil pack starting to go bad? Any other thoughts?

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2003 A4 1.8T Multitronic
6000K Xenon HIDs
Lip Spoiler

How old are your spark plugs and what kind do you use?

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B6 A4 1.8t Avant Quattro Sport Tiptronic REVO stage 1

The previous owner replaced the spark plugs at 40K at the dealership. I have a little more than 20K driven on the plugs.

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2003 A4 1.8T Multitronic
6000K Xenon HIDs
Lip Spoiler

Don't know. But what you are describing is misfiring. On a cold engine one would suspect plugs are not firing for some reason. I would want to pull the plugs and look at them, check the gap. The gap is supposed to be .032 and when I checked mine they were set at .025 - .028, which will cause cold firing. Looking at them will tell you if they are fouled from oil or moisture too. Coil packs are problematic but I would think you would have hot problems instead of cold problems.

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B6 A4 1.8t Avant Quattro Sport Tiptronic REVO stage 1

OK, I will look into that. But gapping aside, is it about the right time to be changing the spark plugs?

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2003 A4 1.8T Multitronic
6000K Xenon HIDs
Lip Spoiler

There are a lot of varying opinions on which plugs to use. Some believe copperare best and change them at 5k. Platinum are factory plugs and can last 40k. I am using platinum and won't change them until I see them wear. But it really depends on who you talk to and if they have performance upgrades. Perhaps others will add some info here.

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B6 A4 1.8t Avant Quattro Sport Tiptronic REVO stage 1