QuestionI have a 1997 gmc 5.7 1500 pickup 4 months ago i had a miss. so I replaced wires,plugs,coil,tps,fuel filter,crank sensor,cap,ignition module,and rotor. None of this helped it still missed. I took it to the shop and he adjusted the timing and it worked. he had also checked the fuel psi and it was good. now about 4 months later I am expereincing a miss. it only happens when i first start my truck in the mornings, and usually takes about two blocks of driving for it to begin, but it only last for about 2 miles and then the missing quits. any ideas on the problem?
AnswerHi
Does the service engine soon light come on?
If so get it scanned, probabally a P0300 misfire.
These vehicles have poppet noozzle fuel injectors.
They are pretty common for the poppet nozzle to get stuck, especially on cold start up's.
I would check 2 things. I would have your mechanic hook a scanner to vehicle, and watch the misfire data and see exactly which cylinders are missing. I would then preform a fuel pressure drop test on these cylinders and see if the injectors are pulsing properly.
If so I would then look inside the distributor cap and see if there is any corrrosion on the rotor tip or the tips inside the cap. If so I would replace the distributor assy.
If all this checks out OK, I would then suspsct an engine mechanical problem (Intake gasket leaking, worn cam lobe, sticky valve, leaky valve etc.....)
Just advice from experience.
Hope this helps.
Good Luck
Pawl
