P0302 misfire, can't fix it

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Cheyenne

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Hey so I had a misfire in cylinder 2
Did plugs, wires, cap, rotor and didn't fix it...
So I did the intake gasket, the upper intake and put in Delphi fuel injector upgrade. On the old injector, the tip on cylinder 2 was visibly burnt.
Finally got it started again today and after a while the p0302 code came back.
I'm not sure what it could be now. What would my next step be?
 

magimerlin

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I'd do a compression check. And also pop your valve cover off and make sure that both the intake and exhaust valves are in fact moving. They should move up and down roughly the same as each other...

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Cheyenne

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I'd do a compression check. And also pop your valve cover off and make sure that both the intake and exhaust valves are in fact moving. They should move up and down roughly the same as each other...

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I did a compression test before and it came out fine
 

1996on22s

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Did you get this resolved? I put new heads on my 96 k1500. All new gaskets. Compression was fine before removal. All valves are new and the rockers where adjusted. I’m having a misfire on cyl 1,2 and 3. Code P0300. I’m thinking I need new injectors. Not sure if that’ll fix it.
 

phaessler

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what year is it ? am curious as to which ignition system is in place.
 

BOTTLEDZ28

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I've been having the same issue for a couple years now. I do not get any codes but I do see the misfires show up on my Dash Command app. The torque converter is also unlocking around 2K RPM which is where the misfires are happening. Its mainly Cylinders 2 and 4. I have already done a new Delphi spider a couple years ago. I just did cap, wires and plugs last weekend and its still present.
I'm starting to wonder is a cracked head would cause a misfire.
 

Cheyenne

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Did you get this resolved? I put new heads on my 96 k1500. All new gaskets.
No. It hasn't been fixed.

compression test will come out fine even if exhaust valve is not opening
I wasn't aware of that.

A leaking intake gasket will cause a misfire.
I put in New intake gaskets, new injectors and intake manifold. Along with plugs, wires, cap, rotor.


what year is it ? am curious as to which ignition system is in place.
1998. 350 Vortec

I'm starting to wonder is a cracked head would cause a misfire.
I wonder that too. I have a rough idle only misifire on cylinder 2
 

Supercharged111

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If it makes you feel any better, my #2 misfires the most too. My misfire is at idle, very light cruise (TP just above coasting), and at WOT. Sometimes it doesn't do it though, usually it does. When it misfires at WOT the MIL flashes. I programmed the PCM to ignore the idle misfires and will likely have it ignore the cruise misfires as well.
 
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