2dr98xj

HI I'm NEW To This Forum Hope I'm Doing This right. Just bought 98 jeep cherokee 2dr...when I got it the map sensor was bad and they installed new distributor but was in wrong now everything is in right it backfires once in awhile thru intake like it did before but either revving up or restarting the jeep it goes away....cps is mopar and brand new new plugs wires cap rotor fuel pressure is good and if I unplug front 02 sensor changes nothing...

killbox916

Usually when an engine is backfiring and the person thinks the have the timing right its because the timing was set 180 out, or TDC on the exhaust stroke vs the compression stroke.

Are you sure that it was TDC on the compression stroke?

2dr98xj

Tbh no I can't but if it was timing wouldn't it do it all the time and never clear up? If I shut it down and restart it it will run fine all day or until next restart or sometimes you can even rev the motor out of it

killbox916

Yeah that is strange. Any codes? I would go through the timing portion one more time....I think something is off. Are you able to do it yourself? Should be a few threads on here showing how to set it.

killbox916

Found this

https://www.cherokeeforum.com/f2/bac...intake-229097/

2dr98xj

Only code is open circuit 02 bank 1 I unplugged it no change and was a code for crank position sensor changed it the new distributor has new cam position sensor in it but yeah mechanic of 30 years set timing for me

killbox916

Here's another thread pointing at O2 sensors
https://www.cherokeeforum.com/f2/00-...-today-207281/

killbox916

People having similar problems with the fix being an O2 sensor and you also having an O2 sensor code....I would change the O2 sensors

2dr98xj

Ok will give it a shot tomorrow as I'm out of state at the moment would unplugging both of them cure the problem just to test it out before buying them

killbox916

Probably not, but you could try it. I would take 5 minutes to look at the #1 sensor wiring as well....just make sure there is nothing obvious.

You could take it to a parts store and have them put the ECU reader and see what the values of the #1 O2 sensor are. Sometimes if you have a bad sensor the reading will be blank or have an XX in the corresponding readout.

But if it were mine....I would just change them....btw you can find them much cheaper online than the local store if you're not in a hurry.

2dr98xj

I can get the ntk sensor's from danger zone where I live for 3 dollars more than the net price so once I get back I'll grab one at a time and try it out and I will keep reportin till I find issue it may help someone else

killbox916

10-4...sure hope this fixes it, computer is telling you it's a problem either way.

2dr98xj

Ok so it ended up being a mixture of problems one being the cam position sensor or the pickup coIL which ever u prefer the big flat piece of plastic in distributor was a knock off brand she said heck no replaced with a USA part only had slight hesitation and with 02 sensor off runs fine so pickING up one today but no more intake backfire thank you gus so much also I found out that the brand OEM from amazon makes pretty good quality parts

2dr98xj

Ok so after replacing cam shafts position sensor\pick-up coil and cps sensor and o2 sensors I have a misfire or hesitation at 2k rpms only goes away if I floor it or stay below it only code that popped was p1391 I cleared it drove the 10 miles to work no code repop but still misfirin or hesitation at 2000-2100 rpms...no more back fire thru intake tho

MWMahoneyJr

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