SD cars are finicky about cams at idle and part throttle because of the inevitable lose in engine vacuum. They rely heavily on the MAP sensor to determine engine load. A low vacuum signal tells the computer the engine is under load and it reacts the only way it knows how, with more fuel. The O2 sensors then read rich and the computer gets stuck in a weird loop it can't figure out.
Lesson is: go heads, intake, LT headers, and 1.72 RR and avoid the aftermarket cam until you can convert to mass air. The few hp at WOT really isn't worth the headache.
|