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ottermiller
New User
Apr 12, 2007, 4:21 PM
Post #1 of 3
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97 gmc miss fire ?
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i have a 97 gmc 5.0l 4x4.small history of the on going problem i have. was running rough at 65 on high way miner shacking. next day stared the truck engine light came on. check the code with a neighbor, Miss fire. after investigating, plug wires 2,4 were shorted. ok easy. cap, rotor, wires, plugs. still same problem. thought i might be losing compression. compression tested each cylyder, 150 in 1,2 135in 24637, 105 in 5. seams ok. apon pulling plugs 1357. plugs were black and smelled of fuel. 2468 plugs were brown and dry. anybody with any ideas thanks shaun
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Guest
Anonymous Poster
Jun 21, 2009, 3:42 AM
Post #2 of 3
(3616 views)
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Re: 97 gmc miss fire ?
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i have a 97 gmc 5.0l 4x4.small history of the on going problem i have. was running rough at 65 on high way miner shacking. next day stared the truck engine light came on. check the code with a neighbor, Miss fire. after investigating, plug wires 2,4 were shorted. ok easy. cap, rotor, wires, plugs. still same problem. thought i might be losing compression. compression tested each cylyder, 150 in 1,2 135in 24637, 105 in 5. seams ok. apon pulling plugs 1357. plugs were black and smelled of fuel. 2468 plugs were brown and dry. anybody with any ideas thanks shaun
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Sidom
Veteran
/ Moderator
Jun 21, 2009, 6:59 AM
Post #3 of 3
(3612 views)
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Re: 97 gmc miss fire ?
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Well there could be a few thing going on with that. GM has problems with there injector, regulators leak. Take a pressure reading & see if it holds. Get the truck up to temp & disconnect the coil, crank it over & if it diesels more than likely you got some leaky injectors. That #5 cyl is low, something going on there. They also have problems with crossfire in the Dist cap, I've even seen new aftermarket caps crossfire & because of the design you can always see visual evidence of it. That engine has a problem with valves sticking, that could be you high speed miss. Rig up a vacuum gauge & take for a drive, see it the vacuum is shaky, that would indicate a sticking valve... That's just a few ideas.... HTH
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