Hello guys, I'm having an issue where my engine misfires upon a cold start up. As I get it to operating temp, it goes away. We all know metal expands when heated. I'm starting to think that my valve adjustment is out of spec. I searched but I can't find any info on valve adjustment on our engines. Anyone can help me out on this?

 

Are you losing coolant too? Rough running on the first cold start of the day is often a sign of a leaking head gasket. Water gets in the combustion chamber and the engine runs rough till it's all blown out the exhaust. You typically see what smoke and might smell burning anti-freeze too.

When the engine is cold, the valves should be at max clearance I'd think. Then get tighter as the engine heats up. Meaning I'm not sure your theory is true.

 

Valve adjustment is $600 + at the dealership, I had mine done last year, I heard mine when the engine warmed up and it never triggered a misfire in the 8 months I had it when I bought the car until I got it fixed, your problem may be something else...

 

I checked my oil and I see no signs of coolant mixture. I may have to perform a chemical block test to confirm if the head gasket is ok or not

 

Rarely does a head gasket contaminate the oil. Typically you see symptoms in the coolant recovery bottle. Where the level goes higher than it should when you finish a decent drive. It might be bubbling too from exhaust gases.

It's not really an issue if you're not losing coolant. Are you losing coolant? I just threw it out there. I wouldn't suspect head gasket unless you had other symptoms in addition to the cold mis-fire.

 

It's very unlikely that excessive valve clearance would cause a misfire. Unless the engine sounds like a threshing machine when cold, look elsewhere.

 

Thanks for the insight guys, I will further investigate. My car has been down since Sunday due to a clogged catalytic converter. I'm waiting for my OBX header to come in.