1995 FZJ80, 230K mi.
Sorry in advance for the long post but I’m trying to document all my troubleshooting to date. I was heading home from a trip and the truck began running rough and the CEL came on. The CEL light would blink under heavy throttle indicating serious misfire. I plugged in the code reader when I got home (30 miles later) and got P0302 (misfire cylinder 2). I figured it wasn’t bad gas or a fuel pump / pressure issue since those would affect all cylinders. The plugs, plug wires, and cap/rotor had been replaced 5 years (only 5,000 miles) ago. There is no apparent water in the oil or oil in the coolant. I pulled the #2 plug and it looked tan (not oily) and basically normal. Based on research here, I suspected either a bad injector or melted wiring by the EGR.
I pulled off the wrap on the wire bundle and inspected all the wires. Nothing was melted but I re-wrapped with heat tape anyway and re-routed away from the EGR so it’s nice to have that done. Not finding any issue with the wire bundle, I removed the intake plenum and checked continuity on all injectors. All were within spec but, since I was all the way in there, I decided to pull all the injectors and send them to FIS to be cleaned. All injectors were cleaned and all flow tested fine. I checked continuity to chasses ground at each of the injector connectors and they all tested exactly the same (no continuity on one lead, and about 500 ohms on the other lead which is presumably the ECU) so it doesn’t seem shorted anywhere (like by the glovebox for example). I also drained the fuel tank just to make sure there was no bad gas / water in there.
I re-installed the injectors (with new gaskets) moving the #2 injector to another cylinder in the process. I replaced all the small water and vacuum hoses while I had the plenum off and also bypassed the rear heater and replaced the heater valve. I got it all put back together and started it up. It immediately idled rough (about the same as before). No CEL immediately (probably reset from having the battery disconnected for 2 weeks) but CEL came on within a couple minutes. It has the exact same code P0302 for the exact same cylinder.
I’m now at a loss. I could try replacing the plugs / wires / cap again I guess but it kinda seems like I “just” did that. I don’t have a compression tester. It may be time to drop it off at the dealer and just bend over unless somebody here has something else to check. Any ideas?? Thanks in advance for your help!
Sorry in advance for the long post but I’m trying to document all my troubleshooting to date. I was heading home from a trip and the truck began running rough and the CEL came on. The CEL light would blink under heavy throttle indicating serious misfire. I plugged in the code reader when I got home (30 miles later) and got P0302 (misfire cylinder 2). I figured it wasn’t bad gas or a fuel pump / pressure issue since those would affect all cylinders. The plugs, plug wires, and cap/rotor had been replaced 5 years (only 5,000 miles) ago. There is no apparent water in the oil or oil in the coolant. I pulled the #2 plug and it looked tan (not oily) and basically normal. Based on research here, I suspected either a bad injector or melted wiring by the EGR.
I pulled off the wrap on the wire bundle and inspected all the wires. Nothing was melted but I re-wrapped with heat tape anyway and re-routed away from the EGR so it’s nice to have that done. Not finding any issue with the wire bundle, I removed the intake plenum and checked continuity on all injectors. All were within spec but, since I was all the way in there, I decided to pull all the injectors and send them to FIS to be cleaned. All injectors were cleaned and all flow tested fine. I checked continuity to chasses ground at each of the injector connectors and they all tested exactly the same (no continuity on one lead, and about 500 ohms on the other lead which is presumably the ECU) so it doesn’t seem shorted anywhere (like by the glovebox for example). I also drained the fuel tank just to make sure there was no bad gas / water in there.
I re-installed the injectors (with new gaskets) moving the #2 injector to another cylinder in the process. I replaced all the small water and vacuum hoses while I had the plenum off and also bypassed the rear heater and replaced the heater valve. I got it all put back together and started it up. It immediately idled rough (about the same as before). No CEL immediately (probably reset from having the battery disconnected for 2 weeks) but CEL came on within a couple minutes. It has the exact same code P0302 for the exact same cylinder.
I’m now at a loss. I could try replacing the plugs / wires / cap again I guess but it kinda seems like I “just” did that. I don’t have a compression tester. It may be time to drop it off at the dealer and just bend over unless somebody here has something else to check. Any ideas?? Thanks in advance for your help!