Missing in certain RPM range.
 

My 01 tj with the 4 cyl. has started to miss at about 1900-2100 rpm. It runs great other then that. This jeep had an deep water excursion last year. I replaced the TPS unit, plugs, wires, cap & rotor after that. When I get to around 1900 rpm it misses and if I am cruising at around 2000 it starts missing. I have no engine codes as of right now... Let my know what you think. Is there another senor that could be bad? Like the Map sensor or O2 sensor or something....? Also it always seems to idle lower than my other Jeep is there a throttle ajustment on it? :confused:

It is not the clutch slipping is it? Could be the coil? Not sure though. Inject it with propane!

Does it miss under acceleration or when cruising? Does it happen at WOT? Or does it happen all the time?

AARON

It misses on acceleration when it hit 1900-2000 rpm before or after that it accelerates fine. When cruising it runs fine below or above that range. As soon as the rpm drop to that range it starts missing? It only happens in that range with the engine hot or cold. At WOT it will hesitate at the same range? Thanks, Danny

Someone else suggested the coil also. I will have to check that out. Did you sell the 94 Truggy? Can wait to see the new one. How does that propane injection work? Thanks, Danny

Propane is simple but what you have is fine and just needs some tlc.

Its been my experiance that when a coil starts to go, it effects higher RPMs first, then hits the lower range. I would look at the MAP sensor. Ran into a similar issue with the motor in my XJ. Ended up replacing the MAP sensor and tweaked the connector and it ran fine.

AARON

Would the Map sensor throw an error code? Or maybe not since is not missing all the time? Thanks, Danny

It wont always throw a code. Mine didnt and after going through everything else, I replaced it and the problem was fixed. I thought it was my ignition and took out the MDS box and was still there, then went through and put everything back to stock and still didnt fix it. After that I started going through and testing all the sensors and the MAP sensor was still with in spec but right at the bleeding edge of being ok. I replaced it and everything was fine after that. This was on an OBD1 system, the OBD2 might be a little different but the symptoms seem to be the same. Get out FSM and test the sensor and go from there.

AARON