ZooKeeper

1988 Jeep Cherokee XJ 4.0

So I brought this Jeep back to USA from the Caribbean. When it arrived, I replaced the engine with a reman 4.0 (not HO).
Installed everything new. (you name it, it's new)

Cruiser54 list - Almost all done

The problem:
Coming back home from a weekend of diving, the XJ started "bucking" at approximately 50 mph. I limped home at under 50 and using backroads, 200+ miles!!!!! LOL

Here is what the XJ does:
Start the XJ and it idles fine. Drive below +/- 2200 rpm, and all is well. As soon as it hits 2200ish, it misfires cylinders 3 & 4.

Fuel side: Checked fuel pressure, 31psi/39psi on the button.
Ignition side: I'm stumped. Took all the new parts to advanced and replace then. New sparks, new Accell wires, new distributor.

Still misfires on 3 & 4.

Any help is appreciated.

ZooKeeper

bump

cruiser54

Are 3 and 4 plugs wet or dry after this happens?

ZooKeeper

Hey Cruiser, started the xj, reved it up, and checked both and both are dry.

Also, I tested spark with a tester. 1,2,5,6 were fine. 3 & 4 misfired at 2200 rpm.

ZooKeeper

Added note: hooked up a spark plug tester to 3 and 4 (individually). Sparks were fine until rpm exceeded 2200, then misfired.

cruiser54

If they're dry, seems like there's no fuel getting squirted into the cylinders.

3 and 4 fire right next to each other. Check plug and injector wiring.

cruiser54

Have you done tip 27?

ZooKeeper

Thanks, Cruiser. Will check them today. And yes, 27 done, C101 eliminated.