Misfires P300,301,304,308 after Head Gasket Replacement
 

Hello Everyone,

This will be the 2nd time I've had this engine out of this truck, this time due to burning coolant. Turned out the left side gasket failed between the front of the #1 cyl and the front coolant jacket. I did use non-OEM gaskets which I was told by Turner Engineering loose there elasticity after about 2 years causing leaks. Not sure why I didn't use the OEM gaskets first time around, stupid move. I also had an oil leak right after I replace the engine with a Turner Block which I thought was due to an issue with the rear main seal. Turns out after I had the engine out it appeared to be coming from the cam plug and two oil gallery plugs above this plug. I replaced the Cam Plug sealing it with RTV and the Rear Main Seal of course and no leakage.

So got everything back together, replace plugs with E3 Plugs, had to replace the wires again due to pulling the spark plug boot off on the Kingsborn 8mm wire I replaced two years.

The problem is that I'm now getting P300, P301, P304, P308, P1174 meaning I'm misfiring and running lean. The engine at idle runs a bit rough, but above idle speed it runs fine. I've look for vacuum leaks/exhaus with nothing found.

I've check wires for incorrect installation and all is correct. Now I did use cheapo wires from NAPA which are 7mm. They actually look like very nice construction for the $30 they cost me.

I'm lean towards it being an MAF sensor issue since this is one item that has never been replaced with 100K on the truck. I have the typically cracked tangs on my airbox and taped up MAF connection to airbox which I feel is sealed up enough to prevent leaks.
MAF, Coils, etc at it.

Any suggestions would be much appreciated.

Perhaps go out in total darkness and look for arcs from coils, boots, plugs, wires, etc.

that sucks that turner did not seal the oil gallery correctly. you may want the try a smoke test to look of an intake leak.

Hey Buzz,

Not sure why I'd have arcs with new wires?? I'll look tonight. Still amazes me that they jammed that coil all the way in the back of the engine. I'm very tempted to move it possibly to the top of the intake.

One interesting note is that when I remove the MAF plug the engines does run a bit smoother. Would a faulty MAF sensor have anything to do with a Misfire?

This, then check the MAF. I doubt your wires are the problem unless you wired them incorrectly. I've got the same NAPA wires and they've been going strong for nearly 3 years now.

I can see on my scan gauge that my MAF Sensor is sensing. If it's working does this mean it is good or can it be out of tolerance?

Yeah it sure did suck that I've had to mop up oil in my driveway for two years thinking I incorrectly installed the rear main seal.

How do I do this smoke test??

to be totally honest I just use wd40 or carb cleaner but that is unsafe. I think if you look on utube you will find something.

And just spray it on the engine surfaces looking for the engine to suck it in?

I used it with the straw, if you hit a leak the rpm with change. but caution not the recommended way to do it.