3.4 Misfire

I've got a 1997 LX with a 3.4 that has a slight misfire when I start it up when it's cold outside (let's say below freezing, 32°). It then will clear up after about 5 seconds and run fine. Anything above that and it starts up fine and doesn't misfire.

I unfortunately am pretty sure I know what it is (head gasket(s)), but I thought maybe someone else had similar issues and it turned out to be something else?

 

Are you losing coolant?

 

I don't seem to be, and as far as I can tell there's no coolant in the oil and vice versa.

 

Could be an injector or a coil/wire.

 

Throwing any codes?

TB could be dirty/cold.

Battery could be dying.

 

Only code it's throwing when I read it last week was for the heater circuit in the rear o2 sensor. At one point it was throwing the CEL for a random misfire. I have 3 extra coils I'm going to replace the ones in there with and see if that might fix it.

 

Check the coils are good. Check fsm for resistance spec.

Plugs and wires fresh/ish?

Fix problem related to code.

 

Plugs were done probably 15-20,000 miles ago. Wires haven't been done AFAIK.

 

Do wires and plugs same time. Good practice. Rock auto has denso brand wires for cheap compared to oem.

Fix problem related to code.

Clean tb and IAC setup. If issue persists check compression on cylinders.

 

I'll do the compression test first to see if that's the issue before I start throwing money at it.

 

Mine was a gasket! I had a misfire on 1,2,3.(P0301, P0302,P0303)

 

I bought a compression tester and I'll see what it comes back to me with tonight.