01 tundra cylinder 8 misfire

Hi my 2001 tundra 4.7l is having a misfire on exclusively cylinder 8. I have replaced and swapped around the spark plugs, moved the coil packs and fuel injectors around, and I Replaced the in line fuel filter but I still have a misfire on just cylinder 8.

Any ideas on what to do?

 

If you swapped the spark plug and coil pack from another cylinder, then cleared codes, and it persists…

Then it’s likely going to be one of two things:

• Your intake gasket is compromised on that cylinder and allowing too much air into the cylinder. In which case you’d be burning lean on that cylinder and the normally-white parts of the spark plug would’ve been tan. If this is the case you may also hear hissing/sucking sounds near the rear passenger corner of the block UNLESS it’s on the valley side of the gasket.
• Your injector on that cylinder is bad and not pumping enough fuel, in which case you’d likely see the same plug conditions OR it’s dumping too much fuel and the plug would be black and grimy from running rich.

I think the next non-invasive step to take would be swapping injector on cylinder 8 with the one on cylinder 6. Lucky you, those are the easiest to reach. Be cautious to make sure the o-rings/seals come with each one, you don’t want to double/seal one and not seal the other.

If the misfire changes from P0308 to P0306 after swapping injectors, your injector is your issue.

 

I previously swapped the injectors on 6 and 8. All the spark plugs look exactly the same as far as color and wear. I ended up doing the intake gasket and knock sensor and p0308 still came back a few days later. Could it be a bad 02 sensor? Or any other ideas.

 

Time to leak down/compression test. If those are good you might need to dig into the wiring harness.