Misfire on cylinder 4 code p304. We have replaced the spider fuel injector, the distributor, all spark plugs and spark plug wires, we did a compression test and all of the cylinders have good compression. After we did all of that the code that pop out was a p1345 so we took it to a mechanic to the timing right and the p1345 seems resolve but now we are still getting a p304 code any suggestions on what else could it be? (Can any faulty wiring cause a misfire on a cylinder? or a computer error?)
Check the misfire topic in our FAQ and see if there's anything you missed.
You don't seem to be complaining about any driveability issues, more about a pesky, recurring, P0304 code.
It would be useful to determine when the computer is throwing the code.
Does it always throw the code during a "cold start" warm-up?
Does it always throw the code at idle?
What do the fuel trims on that engine bank look like when it throws the code?
Obviously I'm alluding to an intake manifold gasket leak on the #4 cylinder's intake manifold port where it mates to the cylinder head.
You also have coolant flowing through ports in that intake manifold gasket. So a vacuum leak (which could cause a misfire) sucking on a coolant leak would certainly add to the probability of a misfire.
GM used a plastic "composite" for the OEM intake gaskets and they're a known "problem area".
They still sell them so if that turns out to be the problem don't use the OEM. Felpro manufactures a gasket with a metal core and rubber gaskets lining the ports.
So like I said. Use your scanner to figure out when the code is being thrown. (Freeze Frame).
Clear it and check it a few times to establish a pattern (if any).
Intake manifold gasket leaks are (almost) always more severe during "cold start" warm-ups and idling.
Have you checked the headgasket?
he said he did a compression test
Hi guys it throws the code right away as soon as we turn the truck on Thank you guys no I have not check the head gasket yet, but i will check the intake manifold gasket because when we replace the spider injector there was some kind of oil base inside the Where the spider injector is. I will replace the intake manifold gasket then and see if that clears the code p304 misfire. Thank you 😊 so much I will let you know what happens.