2000 4.0 #2 misfire

Hey All -

This 2000 is puzzling me. Came to me with a cracked head (0331), which I replaced with a TUPY reman. Good cylinder pressure and no vacuum leaks (tested both). Installed new plugs (Autolite APP895) while I was replacing the head.

Here's the puzzle - starts up, but has a consistent miss on the #2 cyl. I pulled the plug and it looks like there has not been any ignition in this cyl, zero wear or discoloration on the plug. Looks BRAND new compared to the typical heat wear after a few miles on the other plugs. I thought maybe this is a fuel issue, so I replaced the #2 injector with one I know is good. Still misfires.

So the real question - this must be spark, but with the wasted spark shared coil system on the 2000+, wouldn't I have a miss on TWO cylinders? How could it be just #2? Anything else you'd recommend checking before I just replace the entire coil rail setup?

Even though they share a common coil does not mean there is resistance in the individual spark plug circuit.

Thanks, that makes sense. The seocndary side might just be bad to the #2 cyl, and fine to its partner cyl.

FWIW, I'm ditching the COP... such a pain. Just picked up the Ksuspensionfab viper coil mod, back to plug wires for this guy!

I went way beyond that.....

XJ_4LOW said:

Thanks, that makes sense. The seocndary side might just be bad to the #2 cyl, and fine to its partner cyl.

FWIW, I'm ditching the COP... such a pain. Just picked up the Ksuspensionfab viper coil mod, back to plug wires for this guy!

Click to expand...

For the paired cylinders, the plugs are usually in series not parallel. So a broken wire would kill spark on both cylinders. To only get one bad spark, you've have to have one plug shorted, or a wire touching the block.