Good evening ladies and gentlemen,
I've been very busy lately transitioning from active duty USN to the reserves... I have to say, the "freedom" is nice, but I'm getting bored! (Un)fortunately, my 1996 Suburban 454 has been keeping me busy.
No CEL, no codes stored.
Once warmed up/in closed loop, there is a significant stumble between idle to 1.5/2k rpm when I give light throttle or when under load. If I give it a significant amount of gas, there seems to be no issue. Once up to speed, there is a slight hiccup on occasion, but again, giving it "more gas" clears up the issue.
Work completed recently (not necessarily related to this issue):
Fuel pump
Fuel filter
Distributor, cap, wires, plugs
All 4 O2 sensors (thanks GM)
MAF sensor
Symptom elaboration-
When I unplug the MAF sensor, which I believe triggers open-loop operation, the problem completely clears up. Runs great, but likely gets terrible mileage, triggers the CEL, and won't pass emissions.
The PCV passes the vibration/wiggle test.
What I think it could be:
Vacuum leak? I sprayed carb cleaner around the few vac lines I could identify, but noted no change in RPMs. Certainly doesn't mean there isn't one.
Intake manifold gasket leak? Unplugging the MAF could be allowing the engine to better compensate for a possible gasket/vacuum leak.
Any suggestions/recommendations would be awesome! Thank you
I've been very busy lately transitioning from active duty USN to the reserves... I have to say, the "freedom" is nice, but I'm getting bored! (Un)fortunately, my 1996 Suburban 454 has been keeping me busy.
No CEL, no codes stored.
Once warmed up/in closed loop, there is a significant stumble between idle to 1.5/2k rpm when I give light throttle or when under load. If I give it a significant amount of gas, there seems to be no issue. Once up to speed, there is a slight hiccup on occasion, but again, giving it "more gas" clears up the issue.
Work completed recently (not necessarily related to this issue):
Fuel pump
Fuel filter
Distributor, cap, wires, plugs
All 4 O2 sensors (thanks GM)
MAF sensor
Symptom elaboration-
When I unplug the MAF sensor, which I believe triggers open-loop operation, the problem completely clears up. Runs great, but likely gets terrible mileage, triggers the CEL, and won't pass emissions.
The PCV passes the vibration/wiggle test.
What I think it could be:
Vacuum leak? I sprayed carb cleaner around the few vac lines I could identify, but noted no change in RPMs. Certainly doesn't mean there isn't one.
Intake manifold gasket leak? Unplugging the MAF could be allowing the engine to better compensate for a possible gasket/vacuum leak.
Any suggestions/recommendations would be awesome! Thank you