DASC at 5000+ ft--my first CEL...argh!!!

[Budget M3]

Had my DASC now for going on 6 years and never had a check engine light (CEL) until a recent trip to Denver. The DASC with auxiliary fuel pressure regulator (stock ECU software) was installed in 2003 and the car spent its first two years in Virgina (~sea level), then the next 4 years in Tucson (~2000+ ft), and recently was moved to Albuquerque (~5000+ ft). The CEL came on while driving from Albuquerque to Denver a few weeks ago which included altitudes up to 8000 ft and sustained engine speeds of 4500+ rpm. The codes indicate it could be a bad air-fuel mixture (running too rich) which actually makes sense to me.

How to fix it though? I had the CEL reset once back in Albuquerque and am hoping the computer figures it out by itself, but if I have to adjust the AFPR to lean out the mixture, how exactly does one do that? I thought I remembered reading somewhere that clockwise turn of the allen screw on the top of the AFPR richens the mixture, and counterclockwise to make it more lean--is this correct? How much to turn it--1/4, 1/2, more?? And where/how should I look to measure if the AFPR adjustments are having the intended effect?

If the computer re-learns the correct mixture and keeps the CEL off, then I won't need to make any changes. However, it sure would be nice to know the procedure if the CEL comes on again!

[xxxJohnBoyxxx]

How to fix??

Reset and see if it comes back...

JB

[Budget M3]

Yes, that is what I did:

Originally Posted by Budget M3

If the computer re-learns the correct mixture and keeps the CEL off, then I won't need to make any changes.

If that does not "fix" it, what is the procedure to adjust the AFPR?

[Budget M3]

Just a quick follow-up....after ~100 miles of mixed city and freeway driving, I am happy to report there has been no recurrence of the dreaded CEL!!!

[Danny318]

Originally Posted by Budget M3

Yes, that is what I did:


If that does not "fix" it, what is the procedure to adjust the AFPR?

you turn the alen screw one way or another to adjust the fuel pressure. you'd need to know if the car was rich or lean, or if even that is what caused the problem.

I'd check for vacuum leaks first.