Crap! After several weeks of things working smoothly, I headed out for an 11 hour drive to Utah and caught the dreaded CEL outside of Las Vegas. OnStar checked it out and said it was an air intake problem and driveable. Pulled into a Chevy dealer in Utah who couldn't replicate the CEL problem (light went out just after I drove in) but that codes P0229 and P0099 were present. They reset the CEL and off I went. Problem came back two days later so I went back to the dealer. Tech called the support line and they said it was the lower MAP sensor. Had to head for Phoenix so we buttoned it up. As expected, the CEL came on and off (seems like five restarts turns the damn light out) a couple more times. Now it's back at my dealer in California for the CEL challenge and the auxillary brake pump. Any ideas other than to re-inspect the MAP sensor wiring?
Thanks.

 

Are you sure it is P0229 and not P0299? P0099 is intake are temperature erratic. The only thing that really could be causing that is a poor connection to pin #2 of the TMAP sensor in the cold side intercooler pipe. Look for wire chafing/rubbing-grounding issues and splice issues.

 

YOu're right; its P0299.
Thanks.

 

Dealer/Tech Line thinks the lower MAP sensor is bad. Replacement part on order - my $ because GM and GMPP are pointing fingers. This sucks.

 

I'm having boost issues now, as well and have been searching the forums today. Have you gotten any resolution to your issues yet?

 

All I can say is: Sure glad I got the Trifecta tune! No problems whatsoever. 25 lbs. of boost anytime I want it, and it don't drop off until I'm ready. " Oh, and talking to Vince at Trifecta this morning, we are going to put a little more to it[especially in 4th gear]. Runs hard, will run harder.

 

Picked my car up today from the Dealership and it's back to running like a Chevy again.:) I was sure as heck tired of thinking I had 4.6L under my hood. They soldered the connections and all is good. Hopefully it stays that way.