Posting back to inform that my jeep stated to do this misfire thing again, just as violent as before. Just suddenly started again.

 

Start with the obvious basics. Plug wires, cap & rotor, pick-up switch in distributor(measure the air-gap with brass feeler gauges). If all those check out, make sure the distributor shaft/gear is tight and not wobbling round(worn out). Merry Xmas!

 

Merry Xmas to you too. You don't know how much trouble I went through fixing this problem. I seem to have replaced pretty much everything. Its for sure not stator, plugs wires or rotor and cap, all of those parts have less than 3k miles on them.

 

on the way to work i noticed that its lacking power too. Its backfiring from the exhaust and does it when slowly accelerating too. It started again after being gone for a long time. I did two things, put 87 gas from Super America ( i only get mid grade or 87 from BP) and i got stuck on a parking lot with a load of snow and was going back and forth for a little while and when the truck finally hooked up it hopped pretty violently, it almost felt like the engine was going to rip itself out of the engine bay.

 

Could this be knock or cas sensors acting up?

 

Ok guys I am starting to get really sick with this issue:-/. The car is misfiing and sputtering like crazy at 1800rpm and light load. What tools are needed to scan the ecu in Renix jeeps? I know ecu does not store codes but while driving the scan tool should show what is causing the stutter/misfire.

 

Ok, so I got a another icm from a junk yard together with a coil. And same issue. So it's not the coil or icm. And I tried a new crank angle sensor. Nothing.

Any ideas?

 

I certainly do not have the knowledge that many folks here do, however the problem you're describing sounds a lot like the misfire I had in mine (2000 auto, 4.0). Would misfire and backfire under load after sitting. I travel for work and when truck would sit for more than a week or two it would run like garbage w/ misfires, lack of power, backfires. WOuld clear up after a couple days mostyl, however misfire never went away completely. After replacing plugs, ignition and computer the prpblem remained. After doing lots of reading and googling and finding similar descriptions I dumped a can of seafoam in the fuel and drove it fairly hard for 100 miles. The problem vanished. No joke. Not even a hint of a misfire anymore. Valves were sticking when it sat for extended periods. After running a few days they loosened up mostly but were still dirty and sometimes stuck.

Not saying that is your issue but worth a try in my opinion.

Good luck.

 

Sounds like a bad or missing o2 sensor.

Check the connections, wires and test the o2 sensor. I can get the procedure from the FSM later if you need it (at work now).

 

An o2 sensor can cause a misfire like that? I will just buy a new one tomorrow and see if it fixes the issue. Can o2 sensor have intermitten issues?

I am getting pretty bad milage too.

 

The o2 sensor controls the air/fuel mix. If the computer is getting a bad (read: not working) signal or even a lazy signal it will default to rich. Meaning the computer will dump more fuel then needed and can cause either an intake or exhaust back fire.

The front (closest to the engine) o2 controls the air/fuel mix.

 

Yeah I know how that works, I just did not think that o2 sensor can cause misfire like that. But I guess it makes sense because when I accelerate it runs fine but when I cruise it stutters and misses. I don't know if Renix has open and closed loop but if when you are cruising it's not using the table for fuel but just uses the readings from sensors, bad o2 can cause misfire.

 

Put in a new o2 sensor. Same issue. Misfires like crazy around 2k at light throttle. I am going to post a new thread just so people understand what's going on.

 

Sorry man.

 

This makes sense. A quick check would be to look while running in a totally dark garage. You may be able to see an errant spark somewhere.