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HELP ME cylindar 6 misfire

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Toocidnab

New member
I have a flashing ses and it brings up p0306 misfire cylinder 6 ive put new spark plugs and wires checked the coil packs and fuel injectors still have misfire p0306 I have backfireing low exceleratiom high knock plz any help would be great thanks in advance I have a 2005 gp gtp
 


^ yep. that would definitely be the first step. Next I would double check to make sure that the firing order is correct. Do a compression check. A bad ICM may cause this issue. pull the harness and check for corrosion and damaged pins.
 
If the misfire doesn't move with it, I'd put a long handled screwdriver to the injector and put your ear to the butt of the screwdriver to listen for the fuel injector actually actuating. If you hear it clicking, I'd do compression test followed by leakdown test if compression is good. I hope for your sake that it isn't anything major! Good luck
 
Do you have any smoke coming out the tail pipe? By the sounds of it, your problem is internal. I'm betting broken spring or a failed lifter.
 
I did check the injectors there good and changed coil packs around still says it #6 I will try to get a compression test done today I'm not sure about smoke oput of tail pipe I will have to check. I hope its not a lifter or broken spring but if it is then I guess I will just get zzp 1.9 rockers
 


Toocidnab said:
I have a flashing ses and it brings up p0306 misfire cylinder 6 ive put new spark plugs and wires checked the coil packs and fuel injectors still have misfire p0306 I have backfireing low exceleratiom high knock plz any help would be great thanks in advance I have a 2005 gp gtp
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I have a similar issue. I service engine soon light is on, there is a misfire on the number 5 cylinder with tapping and engine vibration. There is no smoke from the tail pipe and I still have good power. I replaced all the coil packs, wires, spark plugs and the ignition control module. I either have lifter issues or a bad fuel injector. I plan to examine the fuel injector soon. Good luck with your misfire issue.
 
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davids06gp said:
I have a similar issue. I service engine soon light is on, there is a misfire on the number 5 cylinder with tapping and engine vibration. There is no smoke from the tail pipe and I still have good power. I replaced all the coil packs, wires, spark plugs and the ignition control module. I either have lifter issues or a bad fuel injector. I plan to examine the fuel injector soon. Good luck with your misfire issue.
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Did a compression test they all are 125 or 130 im stuck think maybe a spring or lifter problem

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waupachino said:
Do you have any smoke coming out the tail pipe? By the sounds of it, your problem is internal. I'm betting broken spring or a failed lifter.
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You’d be able to hear a broken lifter and I don’t recall that he said hearing anything. I maybe wrong though. The broken spring is probably a good possibility because then he’s not getting air or fuel. I don’t think you’d be able to hear that one.
 


The spring won't be broken and the lifter won't be bad if you are getting good compression. If the spring broke, the valve would be open.

Do you have an exhaust leak?
What fuel do you run?
If you know anyone with a borescope, it's time to look inside the cylinder at the piston. You may have chipped the landing.
 
BillBooost37 said:
The spring won't be broken and the lifter won't be bad if you are getting good compression. If the spring broke, the valve would be open.

Do you have an exhaust leak?
What fuel do you run?
If you know anyone with a borescope, it's time to look inside the cylinder at the piston. You may have chipped the landing.
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If it’s chipped I don’t think he’d be getting good compression. Piston rings are good then as well. If it was chipped bad enough to break the seal on the piston and cylinder wall he’d definitely know it and would be burning a good bit of oil.
 
GrandPrixGT1 said:
You’d be able to hear a broken lifter and I don’t recall that he said hearing anything. I maybe wrong though. The broken spring is probably a good possibility because then he’s not getting air or fuel. I don’t think you’d be able to hear that one.
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Not always true. In my case the whole roller broke completely off and the body of the lifter was hanging in the lifter bore. No noise, because there was no movement of the lifter. Also if it's the exhaust lifter that's not moving, it would still make compression.
 
Huh. No one has suggested coolant/oil into the cylinder fouling the plug? LIMs done? That being said, It's awfully easy to mix up the plug wires, after fixing a bad plug. Hell. I do most of time, it seems.

More info! Always dead cylinder? Does it gets better after it warms up?, starts missing after it warms up? Idle ok? Only flashes after partial throttle? Half throttle? WOT? Starts flashing as soon it's started? and then only when cold? Only after it warms?

*random thoughts*

This is a No Spark Code. Computer is not seeing engines revs going up after the spark is triggered, Via the crank sensor.

And if its the only code... Back to basics. Battery connections? Grounds? Bad plug, bad wire, wrong wire, fouled plug. Hmm. How old is the battery?
 


Ok so idk why it was coming up as misfire but i belive it to be the tranny 2nd cluctch and 4th gear and oil pump shaft working on those now as long as order some headers and zzp vs cam #90 springs

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150000 plus some change i thought of that i dont think so i had a zzp down pipe with high flow cat not even 18 months old but if for some reason that was the issue im installing headers and going cat less 3.0 in all the way 2 a split into 2 flowmaster 40 series

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