gmc engine still skipping?

JD'S cj7

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Joined
Oct 25, 2006
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REIDSVILLE, NC
O.K. Ive got a 1997 gmc k1500 5.7 that was skipping. Engine light reads random misfire. Ive put new plugs and wires on yesterday. The cap and button were replaced about a year ago. Its still skipping? What else could cause this?
Thanks
J D
 
have you checked to make sure that all the plugs are getting fire? also if the spark should be a blue color....

did it say anything else as far as what cylinder might be misfiring?
 
JD'S cj7 said:
O.K. Ive got a 1997 gmc k1500 5.7 that was skipping. Engine light reads random misfire. Ive put new plugs and wires on yesterday. The cap and button were replaced about a year ago. Its still skipping? What else could cause this?
Thanks
J D
Click to expand...

Pull the cap off, and wiggle the rotor, if the dizzy shaft has ANY side to side play, REPLACE the WHOLE distributor and housing assy. May also want to look at the dizzy drive gear, they wear funky as well, and are known for causing radom misfires as well.

These engines have plastic dizzy housings, they wear, and do weird things. ALSO, if you are not already, us GM ACDELCO ignition components, YES, they are more expensive, but they also don't break down internally like the cheap aftermarket parts store junk.

THink about how much power is flying around inside that cap, and then look at the traces for the terminals on the cap. #3 and #5 cyls are NOTORIOUS for crossfiring when using a cheap cap.
 
I have the exact same problem with my 98 Hoe. The plugs have 20k on them and look perfect. Last week I replaced the following with no change in performance; plug wires, distributor cap, rotor, and fuel filter. SES light still on. I had the codes pulled at Azone, and it came back with random misfire. The random misfire only happens at cruise speed (50-75mph). Step on the gas and it goes away and pulls solid, very strong.
 
as voodoo mentioned id be checking the dist. it cruse speed its probably floating vs under load where the gear would have more force on it..
 
oh, also replace the fuel filter if it hasen't be done in recent history. ( restricted fuel supply will cause a lean miss, which can show up with no other codes)

And if it hasen't been replaced regularly, and you DO replace the filter, save your soup labels, cuz the fuel pump will be doing the death spiral in the near future ( carry a hammer to beat the tank, so you can get home)
 
It maybe the intake gaskets leaking they are bad for that on the 4.3 and the 5.7 so I would check for that also. That will cause a miss fire because it will be sucking to much air.
 
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