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P0300 Code. Random Misfire NEED HELP!

JcGTP39

JcGTP39

New member
Okay I'm so stumped on this one guys did everything that I know that could cause this issue. It misses at idle. when you put it in drive you can't feel it cause there's a load on it.
What I've done
New Plugs gapped to .60
New wires
New Colis
Up stream O2 sensor is good replaced that 4 months ago
No Converter
No Downstream O2
Tested the the coil Module like 6 times test out good
Could it be the injectors or possibly a PCM? I just orderd one from zzp for black Friday should get on Wens, tell me what you guys think thank you
 


Plugs are autolite double platinum 104 I had delco ones in it still did the same ones. Wires are NAPA premium and so are the coils and the o2 the OEM one that plugs right in
 


With just a cold air, you shouldn't be running 104s. Switch them out with stock temp plugs and your issue should go away.
 
I did. I had AC delco's in it that had like 5000 miles on them and did the same thing. I got a smaller pulley and that PCM and SLP headers ready to throw on just want to fix this first before I do
 
Yeah I read all that. But if the cam sensor was bad that would throw a code same with the EGR. If the exhuast valve it run really ****ty when your driving. So I'm down to PCM or injector.
 


If it's a single injector it should be a cyl code instead of random, and I really doubt that the PCM just decided to go out.

The CPS won't always throw a code when it is going bad.

Can you still hear the fuel pump prime? Is the fuel filter clogged?
 
Yeah true lol. Yeah fuel pump is good possibly could be a filter im going to do a fuel pressure test tmrw at my college and see what it's putting out. I wouldn't think a cam sensor would have anything to do misfire.
 
i would insist in coils or wires...

i have had like 3 p0300 in like 2 weeks dealing with the details of the proyect.
just recheck everything.

i doubt it is PCM nor inyectors.
 
Right on man. Yeah maybe i got a bad coil from napa or something but im working on it all day so hopefully I'll figure it out
 


Well found out its cause a rough idle because sense I cut the cat off and the downstream o2 sensor it's dumping a lot of fuel into the motor. It's running really rich. We will see if anything changes once I throw that new PCM on.
 
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