Mechanics

RUNS ROUGH WHEN COLD

1998 GMC Jimmy

I HAVE A 1998 GMC JIMMY THAT RUNS ROUGH WHEN IT IS COLD, AFTER IT WARMS UP IT RUNS GREAT.
I HAVE CHANGED PLUGS, WIRES, DIST CAP, EGR, O2. CAT CONVERTER, MUFFLER, MAP SENSOR, THROT POSITON & AIR FILTER.
I DON'T KNOW WHAT TO DO NEXT, PLEASE HELP.
THANKS,
DAVE
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Yanks1968
November 25, 2006.




It is normal for a car to run " rough" when its cold. Let your car or truck warm up a bit before taking off. Notice the RPM's. When they get towards the 1 or below, and your engine temp guage reaches midway you know its safe to take off and your car is warmed up.
AD

Tiny
Lsussel
Nov 28, 2006.
ANY CHECK ENGINE LIGHTS ON, THEY DO HAVE A PROBLEM WITH THE INJECTOR POPPET VALVE STICKING WHEN VEH. IS COLD COUSING A MISFIRE, GM CAME OUT WITH NEW INJECTORS FOR THAT PROBLEM. ALSO HAVE U CHECKED UR FUEL PRESSURE, MAKE SURE IT HOLDS, UR FUEL PRESSURE REGULATOR COULD BE LEAKING COUSING VEH. TO RUN ROUGH BECAUSE OF THE RAW FUEL IT DUMP OVER NIGHT. DO U HAVE A HARD START WHEN VEH. SIT FOR A LONG TIME IF SO U HAVE A FUEL PRESSURE REGULATOR THAT LEAKS.

Tiny
GMX
Nov 29, 2006.

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