James Carter
Newbie
So the truck has a rough idle, surges at idle. Long term Fuel trims are -20 both banks. Everything smoothes out when driving on the highway. Map sensor is getting 5v reference key on engine off. Then I start it and it dips to around 2.3v and fluctuates slightly. Signal voltage is next to nothing but there. Any leads on where to start? It's a 1997 k3500. BBC bored to 468ci and it has a towing/RV cam in it. It's the mpfi gen 6 7.4. Symptoms are almost of a vacuum leak but I've tested all around with starting fluid and no dice. Anyone have ecm diagrams from a manual that provides schematics so I can back probe at the ecm?
