The A4 is an '01 1.8T Quattro 5spd, 66k on it (and yes, Dr. Moderator, I was here for a few final searches before I order a timing belt kit from ECS Tuning or similar)...

This is the first emissions test Colorado has required of the car and results are as follows:

- HC 0.0779 against a fail limit of 1.2
- CO 2.4171 against a fail limit of 20.
- NOx 0.1961 against a fail limit of 3.0 (all of these numbers were suffixed by GPM but I doubt they meant gallons per mile, more likely PPM was the intended scale).

I am no emissions scientist but these look pretty good. Car was up to temp, fresh 0w-30 Mobil 1, plugs are recent, and we burn premium gas from whoever's cheapest.

Anyway, will be doing the belt(s) and all the related pieces in the vacinity soon... a question for anyone who reads this far. The car doesn't have the ooompf it used to (I am not the regular driver, so easier for me to notice differences via the butt-ometer). Is there anything else performance related that wears our (bypass valves, heart valves, ???). Thanks...

 

Diverter valves do wear out..

Have someone with a Vag-com check for any error codes.

You are also at high? Altitude?

 

Yes, the diverter vavle can wear out over time. And the gpm is grams per mile.

 

Yes, Longmont is about 5k above, so its considered high altitude... and thx Doose on the GPM. Makes sense now. So the diverter valve could be the cause of 'less than it used to be' performance?

Thx again - appreciate it.

 

Yes it can