Misfire cylinder #8 '96 5.7

[2LaneTraveler]

96 Tahoe 5.7 170k Code PO 0308 swapped plugs with cylinder #1, swapped wire, checked cap and rotor, not new but not bad, I can see spark on #8 plug out of engine still throws PO 0308
Ran compression test left bank 180, 180, 180, 180,
right bank 180, 180, 170, 190
Fuel problem?

 

[lesterl]

Poppet injectors or MPFI upgrade kit? Have you done an intake seafoam treatment? If original poppets you can swap the injector to another location and the code should change to another cylinder. Does the plug look clean, carboned, or wet?

 

[2LaneTraveler]

I'm assuming it has poppet injectors, no seafoam yet. Plug looked and smelled wet.

 

[lesterl]

So it could be flooding that cylinder like with a stuck open poppet...

To check pull the black tube off the top of the throttle body, use a small inspection mirror and a light to look down in throttle body (held at WOT position), you will notice either a couple small black tubes, or white tubing and a couple wires per tube.

The former is poppets, the latter is MPFI.....

 

[2LaneTraveler]

I'm pretty sure it has poppets as I know the previous owner. The good news is after a bottle of seafoam in the tank it is running on all eight and no misfire codes for a week.

 

[lesterl]

Seafoam works pretty good, I seafoamed my intake and put some Techron in the tank....