sandyeggoxj
NAXJA Forum User
- Location
- Sure would be nice to have a home...
99 xj, 4.0l, ax-15, 49-state SE
I parked the jeep in 2015 or so and I haven't ran the engine since. I pulled the battery at that time. Fuel pump went bad so I decided that it made sense to switch to a jaz fuel cell and return style fuel rail with all AN fittings. That project became a bigger project than I had time for and then the kids started coming. Same old story you've heard before.
I'm not 100% sure what I've done since it's been 10 years. I know I ripped out the airbox and built a new air intake. I replaced the clutch with luks parts. I finally got the fuel system done and running fine. I'm measuring around 45psi on the rail while cranking.
Cranks fine but no spark. I immediately replaced the CPS because its a jeep. That was a cheap part store version and it didn't fix the problem. So I replaced it again with a mopar CPS. I never really had the typical problems: never lost communication with PCM, gauges always worked normal, no DTC set.
I've tested sensor ground and 5V constant continuity to the CPS, TPS, IAC, MAP, CAM sensors from the PCM harness on connector A (A4 - ground, A8 - CPS signal, A17 - 5V supply). I tested the resistence of the CPS and I'm getting 4.42kOhm across pins 1 and 2 (sensor signal to sensor ground). I'm unclear if that is normal. Infinite resistance across sensor ground (pin 2) to 5v supply (pin 3)
The ASD relay tests fine and the fuel pump continues to run while I'm cranking. Swapped the ASD relay with another just to test. No change.
If I unplug the CPS nothing changes. I definitely have a damaged downstream o2 sensor from where it used to get slammed into the body when the exhaust would get smashed on rocks. I unplugged it just in case it was shorting to ground but that didn't change anything. Clutch switch functions correctly. Instrument cluster: volt meter is correct, fuel reads nothing because I don't have a fuel sender installed, oil pressure reads low (maxes out gauge if I unplug sensor), coolant temp reads out on my scan tool in the ball park temp I would expect for this time of year.
I have access to a 2006 4.0L TJ with manual trans that I could swap the PCM with if that is compatible. But I don't want to trash that one. I know the ignition is a little different on those. Any other suggestions? Should I try to get the PCM bench tested or repaired? Find a replacement to test? I don't want to throw money at it until I exhaust troubleshooting.
I parked the jeep in 2015 or so and I haven't ran the engine since. I pulled the battery at that time. Fuel pump went bad so I decided that it made sense to switch to a jaz fuel cell and return style fuel rail with all AN fittings. That project became a bigger project than I had time for and then the kids started coming. Same old story you've heard before.
I'm not 100% sure what I've done since it's been 10 years. I know I ripped out the airbox and built a new air intake. I replaced the clutch with luks parts. I finally got the fuel system done and running fine. I'm measuring around 45psi on the rail while cranking.
Cranks fine but no spark. I immediately replaced the CPS because its a jeep. That was a cheap part store version and it didn't fix the problem. So I replaced it again with a mopar CPS. I never really had the typical problems: never lost communication with PCM, gauges always worked normal, no DTC set.
I've tested sensor ground and 5V constant continuity to the CPS, TPS, IAC, MAP, CAM sensors from the PCM harness on connector A (A4 - ground, A8 - CPS signal, A17 - 5V supply). I tested the resistence of the CPS and I'm getting 4.42kOhm across pins 1 and 2 (sensor signal to sensor ground). I'm unclear if that is normal. Infinite resistance across sensor ground (pin 2) to 5v supply (pin 3)
The ASD relay tests fine and the fuel pump continues to run while I'm cranking. Swapped the ASD relay with another just to test. No change.
If I unplug the CPS nothing changes. I definitely have a damaged downstream o2 sensor from where it used to get slammed into the body when the exhaust would get smashed on rocks. I unplugged it just in case it was shorting to ground but that didn't change anything. Clutch switch functions correctly. Instrument cluster: volt meter is correct, fuel reads nothing because I don't have a fuel sender installed, oil pressure reads low (maxes out gauge if I unplug sensor), coolant temp reads out on my scan tool in the ball park temp I would expect for this time of year.
I have access to a 2006 4.0L TJ with manual trans that I could swap the PCM with if that is compatible. But I don't want to trash that one. I know the ignition is a little different on those. Any other suggestions? Should I try to get the PCM bench tested or repaired? Find a replacement to test? I don't want to throw money at it until I exhaust troubleshooting.
