ok so i have 93 with the 318 awd and i have a major problem, i have replaced the fuel pump,filter,cps,coil,pulled the injectors,have done a fuel pressure test,stays steady at 39-40 pounds at idle,and 45 roughly at 2grand rpm, ok the problem she will start up fine most of the time but when she warms up temp gauge gets to 125 she does not want to idle,nor go down the road smoothly,if i keep constant pressure on the gas she runs but rough,but as soon as i let off the gas she falls flat on her face,then takes quite a few cranks to get her started again and then runs rough as all get out, nobody in my realm of friends who all drive and build jeeps has a clue because they all drive the standard Cherokee 4.0 so nobody i know knows anything about these monsters, i have sunk roughly 300.00 in her in the last two days and still the same outcome usually a smooth start up and then bam on her face, I need help BAD PLEASE AND FAST .... i had this posted last-night but it got deleted due to me putting it up as an example on another post so that post has been deleted and this is the original again,,, really needing help this is my only vehicle and i drive for a living....
1. Check for evidence of oil in the intake lower plenum. If there is oil, replace the intake plenum pan gasket.
2. Check the engine vacuum at idle, it should be 19-20".
STALLS ON DECELERATION
1. Test the ISC steps with a scan tool. With a warm engine in neutral, with no accessories on, if the steps are higher than 30 at idle, inspect for a collapsed PCV hose, clean the throttle body bore and disconnect the battery for 10 minutes. Retest for the ISC counts to be between 10 and 28 steps.
I know the second one doesn't help much with out the scan tool. Can you pull the codes by flashing them out of the cluster?
ok plugs wires cap and button all changed,iac i removed and cleaned was not bad at all,pcv hose is fine.not collapsed and is working, i disconnected one o2 sensor and it ran way worse than if it were hooked up now ??? do i have two of these jewels ??? if so where is the other one i unhooked the one before the cat... the whole isc thing i could prolly have my buddy do that he has a computer diagnostic tool, this started out of nowhere one day lasted a day then went away for two weeks roughly and came back last Thursday outta nowhere and has just progressively gotten worse... has broke me seriously and i do not want to do not want to just keep buying parts and replacing them so far nothing i have done has worked....
ok so if that is the case i have unplugged that one o2 sensor and it ran way worse but plugged it back in and it ran like it did before i unplugged it did not run better another words, ok so when i took the iac out i did not clean like the whole throttle bottle should i remove it and clean it thoroughly ????
I have a 94 zj same as your set up and when mine was doing this I replaced the idle air control valve, the throttle position sensor, ignition coil cap and rotor, as well as the cam shaft position sensor, the plugs and wires, and the O2 sensor with the NTK every says you have to have. and after all that it worked for about a month. the NTK O2 sensor went bad twice within a month and a half. and I changed it and got the premium Bosch O2 sensor from advance auto and haven't had any problems with the o2 sensor since. the engine did start to do it's gremlin thing again and I finally broke down and bought a brand new egr valve for it and I haven't had any problem since.
have you tried doing to key trick to pull the error codes from the computer? if so what are they and I can better help you as to which "loop" you are working with.
she is not showing any codes,have a buddy coming out this weekend and he is a dodge man and has similar problems so were going to test the map,tps,going to just tinker around and see if we can nail it down,but by far do not stop giving me your opinions at this point i would take a garage full of people to study her and see what they come up with I have def been writing all your ideas down and going through the elimination process.... and if any or all these work i will def be sure to let everyone know what the GREMLIN was...
ok sooo today i pulled the throttle bottle completely stripped it cleaned it took a look down her throat and looked pretty clean no puddling of oil carbon but nothing that would suggest plenum not being in good shape,my buddy showed up we did all kinds of stuff and he seems to think that my iac is not fully engaging or disengaging ???