1999 5.7 350 vortec P0304 cylinder 4 misfire

[alvaroemg]

Found one spark plug that looked like this and the rest smelled like gas, replaced them all with some spares I had and truck still cranks but won’t fire. My old cap had a crack so I threw on a spare but maybe the spare is bad? The brass terminals look fine. I went through and double checked all my electrical connectors and everything is plugged in.

You must be registered for see images attach

Did you plug in the ignition coil? When i did my lower gasket i had the same issues. I literally had a dream about my work and saw i didn’t plug it in. I woke up at about 7 and headed straight to my truck. Sure enough, it was unplugged.

 

[alvaroemg]

Also, your distributor may be in and plugged in, but you have to twist it to where the flat portion is parallel to the plastic intake.

You didnt leave any paper towels or rags in the intake?

Make sure the injector spider is seated properly on top of the intake. I had to use my palm and lots of pressure downwards to make it seat fully

 

[socal k1500]

yes dizzy flat part is parallel with the flat part of the intake. I didnt leave anything in the intake. i pulled it all out when i went to do the gasket. Ignition coil is plugged in.

I went through all the connectors i cant find anything unplugged, maybe i disturbed one of the ground wires? I have the ground wire connected by the T-stat housing, and the other ground is connected thats near the crank shaft sensor.

you can hear the fuel pump priming. I need to check for spark.

 

[socal k1500]

Kind of a side quest here but I was looking for things that could be disconnected and on the back of the engine there is this cavity hole thing ? It didn’t look right can anyone explain what it’s for. Drivers side of the engine

You must be registered for see images attach

You must be registered for see images attach

 

[Orpedcrow]

You must be registered for see images attach

You must be registered for see images attach

This thing? It’s a freeze plug. Or a casting plug for an oil passage.

 

[Road Trip]

Found one spark plug that looked like this and the rest smelled like gas, replaced them all with some spares I had and truck still cranks but won’t fire. My old cap had a crack so I threw on a spare but maybe the spare is bad? The brass terminals look fine. I went through and double checked all my electrical connectors and everything is plugged in.

You must be registered for see images attach

That plug looks to be heavily all carboned up from a really rich condition. Once everything gets
properly sorted out the porcelain insulator on the new plugs should color somewhere between a
bone white and a very light tan. Q: Did all 8 plugs match each other? Or did 7 look more normal
and this one is the outlier? (Trying to figure out if we have a sensor affecting your engine globally,
or do we have a single dribbly injector giving us a plug looking like this?)

****

Not to focus on the obvious, but have you checked all the fuses in both
the Instrument Fuse Block & Underhood Fuse Block? (If you have, I must have
missed that while reading through this thread.) I wasn't expecting a no-start
after a manifold gasket replacement, so we need to start from ground zero &
prove everything out one step at a time.

 

[Orpedcrow]

yes dizzy flat part is parallel with the flat part of the intake. I didnt leave anything in the intake. i pulled it all out when i went to do the gasket. Ignition coil is plugged in.

I went through all the connectors i cant find anything unplugged, maybe i disturbed one of the ground wires? I have the ground wire connected by the T-stat housing, and the other ground is connected thats near the crank shaft sensor.

you can hear the fuel pump priming. I need to check for spark.

I would still triple check plug wires. Even pull them all off and start over. Did you follow the FSM procedure for stabbing the dizzy? Lining up the little “8” that’s cast into it.

Just spit balling ideas…

Oil pump drive shaft is lined up with the dizzy?
Distributor is installed all the way?

 

[socal k1500]

I would still triple check plug wires. Even pull them all off and start over. Did you follow the FSM procedure for stabbing the dizzy? Lining up the little “8” that’s cast into it.

Just spit balling ideas…

Oil pump drive shaft is lined up with the dizzy?
Distributor is installed all the way?

I double checked wires and firing order. the very first time i went to start the truck i did have 2 plug wires mismatched so i corrected them but it still wouldn't start. The only other thing thats different is that the dizzy cap i took off before i started this repair was cracked so i swapped in a spare i had laying around, idk maybe something is wrong with it?


last year i replaced the ignition coil with some off brand one and i read here on this forum about how crappy the aftermarket ignition coils are maybe it went bad.

my gut is telling me its going to be something silly but i just cant see it. A friend of a friend is a mobile mechanic and offered to diagnose for free. hes going to run through all the basics. Ill let you guys know what they say. My wife is out of patience from me spending all my free time on it so i couldnt say no lol

 

[socal k1500]

Cap and rotor seem fine, the brass looking cylinder contact thing under the rotor on top of the distributor looks chewed up though. Comparing to pictures of new dizzys

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[Road Trip]

Cap and rotor seem fine, the brass looking cylinder contact thing under the rotor on top of the distributor looks chewed up though. Comparing to pictures of new dizzys

I took one of your dizzy photos and put some arrows to something that looks like a failure
of the insulating properties between the center conductor and one of the individual runs?

You must be registered for see images attach

Anyone else ever see something like this in their Vortec caps?

What does a brand new cap look like in this area?

EDIT: What does the underneath of your rotor look like? Any blow-through evident?

Hmmm...