Hi jeepers, im new here. Just need to know what happen to my jeep, run very good when start then after few mile, the engine feels like not enough gas, power down and start to backfire. i have change the fuel pump, filter, coil, spark plug and cable.

 

You need to tell the model year if you expect any decent input.

 

How about at WOT? Does issue clear up? Backfiring at manifold or exhaust? Sounds like the things you replaced didn't help? Need to check sensors like TPS, IAC valve, o2's

Sounds like your fuel delivery is being interrupted. I say o2 issue.

 

I've just had the same issues and they were resolved by replacing both o2 sensors and cleaning the iac helped. I should add that codes were thrown pointing at both o2 sensors.

 

Can be many little simple things like a MAP sensor, fuel regulator, a weak coil pack, if you haven't done a tune up lately I'd check your cap and rotor from corrosion or moisture. Hopefully it's something minor.

 

I have clean the throttle body but didnt change the TPS & O2. I will check n change then. What is IAC? Backfiring at exhaust.

 

The problem with me is no error code at all. . .everytime i check the code is normal. It feels like something getting hot then this.problem happen but i dont know what was that.

 

I have check the distributor cap, cable and also change the coil. Result is still the same. . . :-(

 

TPS is finicky. Might need replaced. IAC is idle air control valve. Works in conjunction with they sensors to help control trim levels. Backfire at exhaust (and sucking a lot of air?) is called dead lean. It's when gas delivery is told to be almost cut off an air delivery to be increased. Brings me back to the o2. Bank 1, sensor 2 probably.

 

My Jeep did the exact same thing you are describing and beleive it or not it was the O2 sensor in the cat . the check engine light never came on until it got to the point that it would die every time I came to a stop

 

Thanks, mean i have to change both my O2 sensor?

 

Thanks bro. . . I will.change it and update the outcome. . .

 

A good OEM, pre-heated one can be expensive, around 100 bucks. Some people seem to have good luck with cheaper ones, but that's not my style. I'd say look into getting it on a good diagnostics machine (while its acting up) to see if you can't help pin point the issue. Good luck man!

 

From what I have been told you can hook up a code scanner that has the ability to watch all the sensors in real time and you can watch both sensors they should read pretty much the same reading (give or take a few points) under normal operation. the bad one will be the one that is fluctuating real bad or or not reading at all. I believe they carry five volts through them at start up but when they heat up they drop to around 2.5 volts. If you have one that is reading 2.5ish volts and one that is stuck at five volts the five volt will be the bad


Hope this helps Im not the greatest at explaining things

 

BTW I used the bosch oem plug style o2 from autozone and that was two years ago