Couple of weeks back, got the 0304 - Cyl 4 misfire. Was going on a trip to the lake, so didn't look much into it. Figured it was due for new plugs anyways. Did the plugs, cleared the code. Drove to the lake and back w/o any codes.
Couple of days later, MIL comes on again. Pull the codes, 0204 - Cylinder 4 Injector and 0304 'pending'. Visually checked for cracked, broken wires.
Check spark plug wires, all in good condition. Pulled dist. cap, visually looks OK. Rotor is a little dark...probably should be replaced, but I would expect to have multiple misfires if that was failing...?
Checked continuity for the injectors - 12.4 ohms across the board (except #3, cos I can't get my fingers behind the accel. cables). Tested elec. harness - noid light shines.
So electrically - injector 4 seems OK.
Mechanically, not too sure...Things I haven't done: Swapped injector with neighbor.
Also a slightly gassy smell, and at one point in troubleshooting noticed smoke from engine bay - appears that fuel ( or something) may have been leaking from where..??? on to the exhaust mani.
Is there anything else I'm missing? I guess the neighbor swap would be the best test at this point. But I'm concerned with the slight fuel ( i think) leak cos I don't wanna be driving and spontaneously combust!
My problem tho, is I'm unsure how to unhook the accel. cables to the throttle body. Any one got tips for that?
Ohm the injectors at operating temp. Drive it around a while then check them, and they will ohm out lower probably 11 or so. A bad injector can read 13+ cold and below 4 or 5 hot and that will set the light. If any read below 10 hot, replace them.
97 XJ, 6" lift with SYE. OTK steering, drop pitman, custom track bar relocated to top of axle, IRO long arm kit, RC disconnects. Powertrax no slip locker in the rear. Stock wheels with 31x10.50 General Grabber AT2's.
1. Finish your tuneup by install new distributor cap, plug wires and rotor. You can't tell much by looking at these items and they are relatively inexpensive. Don't want to chase your tail for $40 worth of parts.
2. Try swapping the injectors from the failing cylinder with another. The "swap and follow" strategy is a very effective troubleshooting technique. Injectors can pass electrically but fail mechanically.
2. Isolate and resolve that leak that is responsible for the smoke in the engine bay before it turns into something bigger....
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche Without "data", all you have is an opinion!
OK - I'll start with the ohm reading while they are hot. Wasn't sure if they needed to be at op. temps, but makes sense - Thanks!
Next, I'll go in on the wires, cap, rotor.
The neighbor swap for the injectors is cool, but like I said - How do you get the accel. cables off the cradle for the throttle body. I've read a few posts where folks have broken them off by applying too much pressures. Anyone have a good visual/video/tips to get them off...?
And yes - that leak. Not all the time, only seems to be happening when I test the injectors and/or harness. When I run the noid light ( that's the screwdriver thing with a light bulb and a positive lead the I clamp to my battery - right?) is it sending an extra fuel up the line causing excess to spill out somewhere (just a thought??)?
So this evening I ran the jeep from work, the grocery store (ran in ran out), and back to home. well within operating temp. by the time I pulled in my drive. Hurried in and grabbed my multi-meter. Checked inject #4 for continuity...13.4 ohms. Same for injector #1 and #2 ran 13.5 ohms. I stopped there. Next on the list will be cap, wires, rotor, but as my plugs are fairly new (they were replaced after the initial p0304/p0204 Friday before Memorial Day!).
So I cleared the codes last night. MIL went off. Good.
Fired her up today to go to work, gassy smell but didn't seem to be missing. Drove 3.2mi to work and she was fine....until I went to PARK. I pulled in the parking lot, took a turn, stepped on the brake to pull into the parking spot, quick sputter/hesitation and boom, MIL back on!?
Does it make any sense that I can drive 3 miles at 45-50 mph and not throw a code, but suddenly...when going 5mph pulling in to a spot she does?
But any who. Off work tomorrow so hopefully I have time to hit the store and finish off my month long tune up!
Just wanted to thrown in an update in case anyone runs into this...
I never swapped the injectors.
Cleaned the grounds, checked connectors. Cleaned up the PCM connections. Thought I did a good job visually inspecting the wiring harness and looms. All looked great.
Replaced the TPS. No change. Some one had mentioned the wires chaffing on the back of the valve cover. I inspected - didn't see anything odd. But I noticed the loom was resting on the back of the fuel rail...and there was a burn. Furl rail burned thru the plastic loom, black tape, and a light blue wire (injector #4).
Taped up and re-routed the loom far away from the fuel rail. All is well no more P0204!!!