Hey everyone. I have a 97 f150 with a 4.6l reman motor which I just put in last week. I'm running to a problem with my number 8 cylinder. I'm getting a misfire code for it.
When I let it idle it has a rough idle. When I put it in gear and let it idle the whole truck shakes. When I drive it the truck shakes up to 2k rpm and at that point it feels like it smooths out.

I put a new injector in, new plug wires, new plugs, new coil pack, and the compression is up around 180 and the rest of the cylinders are within 10% of 180.

Any help would be appreciated Im now lost on what else to look at now

 

On your year and motor you have plug wires.
Have you proven there is no spark on #8 plug wire?
Have you proven the injector is operating?
Do this first to prove which is the problem instead of relying just on parts replacement.
For ignition it could be the coil plug, or the PCM. Are you sure the other coil is not the problem or the plug wire fire order is correct.
For injector it could be the plugup.
A harness issue could be the problem for either one.
Good luck.

 

That's where it gets interesting. I have spark to 8. I replaced injectors as I do not the age of them. And it's a new motor. I checked the ohms on the new injector and that's within the range my book states. Which is 13-19 ohms. I have voltage to the conector for the injector also. I even checked the ohms on the plug wire which also checks out.

 

Some aftermarket wires suck. I always went with Motorcraft on my '97.

Jim

 

If your sure there is spark then the injector is not being operated to inject fuel.
Test for power at the injector connector with the key on.
If ok then test for pulsing ground with the motor running. Don't have to be plugged onto the injector.
If pulsing ground is missing either the harness has an open or the injector driver in the PCM is faulty.
That's all there is left if your sure the plugs are wired correct at the coil.
With incorrect plug wiring, there can still be spark but at the wrong time.
Good luck.