GT Misfire Issues

[rgartzle]

I have a built ‘15 GT with an ESS kit. Been driving it for a little while now, it’s thrown misfire codes since I swapped from the turbo kit it had to the ESS, but they never caused issues with the drivability of the car. About a month ago I was driving it fine and did a pull up to around 8k which then caused it to throw more misfire codes and actually cause the car to not run good, was able to limp it home but it was obviously misfiring.

At this point the car barely runs, surges at idle randomly dropping down to 500 for a few minutes and coming back up. Misfiring on multiple cylinders

Tried crank relearns, replaced the intake with a boss 302, replaced the crank position sensor & trigger wheel, inspected the clutch & flywheel to no avail. Would appreciate any insight because I’m running out of ideas and have sort of run into a wall here

FIC 1000H injectors
Boss 302 manifold
ESS supercharger
Crank sprocket/OPGs

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[WildHorse]

What codes ? P0300 or more specific misfire codes along with others ?

 

[rgartzle]

What codes ? P0300 or more specific misfire codes along with others ?

P0300, P0308, P0306, P0307, P0316

 

[NGOT8R]

I had P300, 301, 304 and 307 after a clutch install. Crank relearn took care of mine, but I saw that you’ve already tried that with negative results.

 

[WildHorse]

P0316

Guessing you popped a few ring lands. OR the very outside chance a head gasket.
Next step: CR test.

 

[rgartzle]

Guessing you popped a few ring lands. OR the very outside chance a head gasket.
Next step: CR test.

Definitely worth a shot and I’ll do one, but wouldn’t I expect to see some pretty decent smoke out of the exhaust if that were the case?

 

[WildHorse]

I expect to see some pretty decent smoke out of the exhaust if that were the case?

Pull the PCV and see how much blowby there is, or if air is being forced out.

 

[BlackandBlue]

Definitely worth a shot and I’ll do one, but wouldn’t I expect to see some pretty decent smoke out of the exhaust if that were the case?

Not always. Compression and leak down will most of the time tell you if she is hurt.

Examine the spark plugs as you pull them. Thats usually a pretty big tip off.

 

[rgartzle]

Pull the PCV and see how much blowby there is, or if air is being forced out.

Cylinder 6 has 0PSI, all others are between 210-235

 

[WildHorse]

Cylinder 6 has 0PSI, all others are between 210-235

Well, either all 4 valves are stuck open, or the piston is laying at the bottom of yer oil pan.

 

[rgartzle]

Well, either all 4 valves are stuck open, or the piston is laying at the bottom of yer oil pan.

borescoped it and the piston looks fine. Going to move it to BDC to check for scoring on the walls but do you think maybe one of the valves is stuck open on just that cylinder alone or it’s not seating properly?

 

[WildHorse]

do you think maybe one of the valves is stuck open

With zero PSI, yes.

 

[rgartzle]

found this rocker roller laying in the head. Assuming lifter failure, still wondering why it would have 0PSI

 

[WildHorse]

Holy. Prolly the valve is bent.

 

[rgartzle]

Holy. Prolly the valve is bent.

Didn’t see anything on the head of the piston, think it’s worth trying to put it back on and checking compression?

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