I have an 88 s4 and I pulled the spark plugs and found bank one is running lean. Bank 2 plugs are a nice chocolate brown and bank 1 plugs are on the white side of the spectrum. Fuel pressure seems to be ok at idle and when I snap the throttle. I currently can't check it under full load. Can the fuel dampener on that bank be the culprit? Any information would be welcome.

 

No such thing as a damper for each bank- there are two system dampers located closer to bank 5/8 than they are bank 1/4 but that is of no relevance.

Perhaps a photo of what you are seeing on the plugs may help a little.

The only things I can think of that would cause a leaning out on a specific bank would be a partial blockage in the plumbing [unlikely] or a cam timing error.

If you can, suggest you do a compression test on all cylinders. If you see consistently higher pressures on one bank compared to the other bank that would suggest a cam timing error of some kind. Cam timing that is comparatively advanced favours higher compression pressures because it is moving more air at the low speeds hence generates a leaner burn at idle conditions.

Is this a problem that has suddenly appeared or is it that you have only just noticed this and it may have been present for some time?

 

I was doing an intake refresh and tuneup and noticed the plugs when I removed them. The car is relatively new to me and cam timing was not confirmed by me yet. This is good information. Thank you! I plan on doing a timing belt in the nearr future. I will check and dial in the camshafts then.