3.4l missfire on cylinder 3

blew head gasket, did both heads. put back together. miss on cylinder 3. replaced plugs and wires. moved coils around. still miss on cylinder 3

 

Could be a fuel injector issue for that cylinder causing the misfire.

 

My thoughts exactly ^

 

Since you had the engine apart recently check to make sure that the #3 injector wiring connector is plugged in all the way, could be as simple as that.

 

Buddy just had same issue. What they said ^^^^. Was the injectors.

 

pulled intake off this evening, to check for anything. all hoses, plugs. are good. moved injectors around, see if it follows. pulled each coil out one at a time and inserted spark plug. all three firing

 

Compression test, just to cover the basics.

 

think i got it. valve shims. low compression in # 3. did compression test before tearing apart, so i knew better. hooked air compressor to cylinder. blowing threw intake. valves were staying open. or not closing all the way. what a pain. anyone had this trouble.

 

So basically...you're way overdue for a valve adjustment?

 

Doesn't look like an easy job, adjusting valves, that is....
http://www.yotatech.com/f128/5vz-fe-3rz-fe-2rz-fe-valve-adjustment-tech-226997/

 

So you're valves are not closing completely....which means the shims are too big/thick. That doesn't make sense....your shims wouldn't have gotten thicker . They can only wear down and cause the valves to open less, NOT in excess.

Your valves my be not closing completely, but I fail to see how the shims are responsible (solely going in the fact that shims cannot get thicker, only thinner). You should look for other components that have failed/worn.

 

Also, if shims are responsible, I would think that they would have to be so far out of spec (SO thick)not only is there zero clearance, but that even when there is zero lift from the cam, they are being pushed open some.

 

I would be willing to bet that during the head gasket job the OP accidentally lost track of the shims/cups and installed one from another location. I suggest doing a full clearance check on all of the valves. Spec I believe is on a sticker on the hood.

 

clearance is .006 to .009. what a hassle. got them all to work at .006 except for three of them. will be hear today. hooked my compressor up to my compression checker. blew air back threw motor. was running right through my intake, with vavles closed. was not an easy job