Why is my motor idling rough???

Asked by May 28, 2014 at 11:10 PM about the 2002 GMC Sierra 2500HD 4 Dr SL Extended Cab SB HD

Question type: Maintenance & Repair

I have the vortec 6.0 v-8, and sometimes when I start it the check engine light will flash and it will idle very rough, and then when I put it in gear and try to accelerate it will bog down for a few seconds until I get it over 1600-2000 rpms. And then the check engine light will flash once and a while while im driving and the acceleration will not be as responsive and it sounds like it may be misfiring. Any ideas? Mass Air Flow Sensor maybe???

2 Answers


Could be mass,but the best way to know for sure is take it and let some one hook it to obd reader,any parts store can do this for free.


How many miles are on it .I have 2002 avalanche and I had the same problem and GM are known to have fuel pumps go out around a 100,000 miles, that was my problem .Take it to get the fuel pressure checked that will tell you if the pump is bad. If so GM put it inside the fuel tank pain in the but to replace you have to pull the tank. Cost about 700 dollars to have it replaced.

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