random miss fire

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dferg
Posts: 1
Joined: Mon Dec 21, 2015 11:28 pm

random miss fire

Unread post by dferg » Mon Dec 21, 2015 11:36 pm

1996 gmc sierra 1500 sle 5.7 keeps throwing code p0300 have replaced plugs , wires , distributor , cap , rotor , coil, truck starts fine then dies at idle .

 

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carriedi
Posts: 2280
Joined: Wed Apr 10, 2013 12:42 pm
Location: Oregon

Re: random miss fire

Unread post by carriedi » Tue Dec 22, 2015 12:27 am

three very common things that can cause a P0300 are:
1. cam retard - check with a scanner (spec is 0 +or- 2)
2. vacuum leak from intake (could be internal leak into crankcase)
3. fuel injector bad or dirty, fuel pressure, fuel regulator, fuel supply leak in intake (check fuel pressure 60-66psi), (do an injector cleaning service), (check for raw fuel in intake)

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