Hey everyone, I have a 98 tj 4.0 with the 5spd Ax-15 trans. About two months ago I gave it a good bath(flooded it) I sucked i! water then turned it off. Trailered it home drained the oil( mainly water) then ran some oil through it and have done about 4 oil changes since then. It runs really Rich and has random misfires, I’ve changed the plugs twice, wires once and both o2 sensors, the tps, the crank shaft sensor(mopar) the cam shaft sensor, the map, cleaned my throttle body, got the intake manifold glass ball cleaned, replaced all injectors, have good fuel pressure and good compression. No bad noises from the motor just runs like crap, I’ve even replaced the header and the cat. I don’t understand what goin on?? Anyone have suggestions that I can try I’m lost
Random misfire / running rich
- Thread starter 98EvaldWrangler
- Start date
Compression is good all within 5 of eachother, only place I have anything coming from is oil from my valve cover
I believe they are walker O2 sensors, also I have a cheap OBD scanner. Ordering a better one this week
I've got a $30 iCar ODB Bluetooth reader and the Torque Lite app and it'll monitor voltages.
-Mac
That's the supply voltage.
You need to look at the actual output...it should increase and decrease with RPM and stay under .9v
-Mac
Upstream and downstream should range with throttle. Can you graph?
Upstream being 0 is suspicious.
-Mac
Upstream being 0 is suspicious.
-Mac
blue is upstream and green is down, I did it while I was giving it gas and the most the upstream got to was .3
PCM? Hopefully someone else can chime in with some ideas.
@Wranglerfix
Did the computer get wet?
-Mac
@Wranglerfix
Did the computer get wet?
-Mac
The pcm sounds like the culprit. Leaking caps are the cause of 80-90% of the issues with early TJ’s. You can send it to us and we can run it in one of our Jeeps and hopefully repair it if it is the computer.
Thanks,
Mark
Thanks,
Mark