Engine Performance problem
2003 GMC Yukon V8 Four Wheel Drive Automatic 115000 miles
I first had trouble with a lack of power and than a the engine light came on and I got codes P0300 and P0430 and after looking in your archives here I found information about an ECM ground on the engine block so I cleaned those up and put some electrical grease on them and it got rid of some noise on the radio that had started about two months ago and when I pulled the truck out of the shop it seemed to have a lot more power than it has had for a while however when I got it up to speed on the highway the engine light came on again and it lost so much power it could barely maintain highway speed. When I pulled the codes again I got P0101 and P0300. I cleared the codes and and as soon as I gained any speed the codes came back sometimes exchanging the P0300 code for P0306. I checked the grounds again to make sure I didn't miss putting a wire back on and I didn't find anything wrong and I checked the wires on the mass air flow sensor for damage and they looked to be ok. I am not running and have never used an oiled air filter and the sensor looked very clean. The truck is now running so rough it is not drivable and I don't know where to look next.
Tuesday, December 1st, 2009 AT 7:59 PM