P0305 or P0300

[SlugSlinger]

P0300 is the DTC for random misfire, P0305 is a misfire in cylinder 5.

The plug on the left is cylinder 5, the right is cylinder 1.

I started the engine for 5 seconds and shut it off.
The endoscope piston image is from # 5


This image is #1.

 

[SlugSlinger]

The issue is a misfire at startup for about 10 seconds then it clears. Trying to figure out if it’s a head gasket or injector issue.

 

[adamsredlines]

Swap the injector...see if the 0305 becomes a 030x (wherever you switched it to)

 

[SlugSlinger]

The problem is I would have to pull the intake to get to the fuel rail and injectors. I’d like to just pull it once.

 

[adamsredlines]

Well there's lots of things that can cause a misfire beyond an injector or head gasket.
Sometimes ya gotta do what ya gotta do.

 

[SlugSlinger]

Yeah, I’ve been through new plugs, coils, wires, checked for vacume leaks. If it’s an injector or injectors, I would rather just pull them all and have them cleaned or I’ll replace them.

it’s an issue on start up. Once it runs for about 5 seconds, it clears and runs fine and doesn’t throw additional misfire codes.

 

[NightShade]

With my truck I just replaced all the injectors since it was at 200K anyway and some of the injector bodies were starting to crack. I went from a 2 hole to a 12 hole injector as well so I thought it was worth it. If the engine has quite a few miles on it anyway and the injectors are not that costly grabbing them and making the swap is a simple proposition.

But a lot of times knowing that information can be very helpful. Some engines just have issues at certain mileage points and without knowing most of that it's like throwing at a dart board in the dark while using arrows instead of darts... Eventually you will find the problem but who knows what else you hit while trying to find it.

 

[PBramble]

Compression test it, then leak down test it. That's some nasty looking crud in there though. Might be valve stem seals leaking too. If it's a coil pack motor, swap a coil with a known good cylinder and see if the misfire moves.

 

[918evo]

It is a clearish liquid that is cleaning the piston, so you are right to assume either an injector or coolant. Maybe try to rig up something to swab the top of the piston and see what the liquid is? I wouldn't waste my time with a leak down or compression test, but you could test the coolant for exhaust fumes. If the engine misfires for the first ten seconds and smooths out, i would also try cycling the key on and off quite a few times and then starting it to see if it misfires longer than usual(this would indicate a leaking injector).

 

[SlugSlinger]

Good advice. I swabbed the cylinder and the liquid smelled like petroleum but when I tried to light it with the torch, it wouldn’t burn.
Cylinders 1,3,5 are wet with the puddle in hole 5. The other side of the motor’s cylinders looked dry.

This is what it looked like this morning after sitting overnight.

It is a clearish liquid that is cleaning the piston, so you are right to assume either an injector or coolant. Maybe try to rig up something to swab the top of the piston and see what the liquid is? I wouldn't waste my time with a leak down or compression test, but you could test the coolant for exhaust fumes. If the engine misfires for the first ten seconds and smooths out, i would also try cycling the key on and off quite a few times and then starting it to see if it misfires longer than usual(this would indicate a leaking injector).