99 cherokee misfire?

[william]

i picked up a 99 cherokee first cherokee heres my problem the jeep starts and runs but it acts like its misfiring i pulled the wires and they all seem to be firing. ive read a few forms and some said the head gasket goes bad and can cause it to run like crap but theres no antifreeze comin out the tail pipe just smells like gas so im thinking the valves are messed up but im really not sure does anyone know how to tell if its a head gasket or the valves are not working right ? i just dont want to pull it all apart and find out i need a head if anyone can point me in a direction i would be your friend till the end lol :bang::bang:

[Cherokee85]

I had same problem, dont wont to alarm you, I replaced everything I could think of before I got it looked at properly, turns out I ended up having to replace the entire engine in my 2.5L (the 4.0L little brother engine) I had extreme piston slap and bores had worn alot, so get a garage to check that too mate, sorry to hear about your issue dude, lets hope its not that, just making you aware.

Joey

[gary63]

first is it all the time or some time if some of the time like after you drove it or it run long enuf to get it hot then off just for a very short time a then start it up and the miss starts but then goes a way.that is very come in. that is heat soaking or so.if it is all the time take the radator cap off when it is cold.then start it up and lot it run until it gets up to running temp.and see it you are getting any bubble or spitting out from it.the other way it a leak down test.

[william]

runs like crap all the time the people i got it from drove it like this for a while they changed the plugs wires cap rotor and still runns like crap the higher the rpms it seems to run smoother ?????? its crazy

[Cherokee85]

mine did that, was better at higher rpm, as the pressure "pulled it all together" and ran smoother, warped cylinder head maybe?

[william]

first is it all the time or some time if some of the time like after you drove it or it run long enuf to get it hot then off just for a very short time a then start it up and the miss starts but then goes a way.that is very come in. that is heat soaking or so.if it is all the time take the radator cap off when it is cold.then start it up and lot it run until it gets up to running temp.and see it you are getting any bubble or spitting out from it.the other way it a leak down test.

ok i ran it with the cap off no bubbles but coolant was coming out just alittle . man i just got it a week ago im a chevy guy but i like jeeps too lol

[william]

mine did that, was better at higher rpm, as the pressure "pulled it all together" and ran smoother, warped cylinder head maybe? im gonna rip it apart prolly next week i never really messed with a jeep but ill learn lol

[Cherokee85]

combine the two and cure the problem all in one, LS1 small block V8 convertion! :-)

check these guys out.....................
http://www.novak-adapt.com/knowledge/xj_swap.htm

[william]

combine the two and cure the problem all in one, LS1 small block V8 convertion! :-)

check these guys out.....................
http://www.novak-adapt.com/knowledge/xj_swap.htm

trust me if i cant figure it out for cheap i was gonna do a chevy motor to the adaptor plate they make for the jeep trans i love to go fast lol

[4.3LXJ]

One thing to check is the plugs. These 4.0s like old school copper plugs. Another thing to do is run some sea foam in the gas tank to clean the injectors and the tops of the pistons

[william]

Ok ill see what plugs are in it in the morning the jeeps at my shop, what plugs do you suggest? Would that make it run like crap if the plugs aren't copper. The exshaust smells gassy but no check engine lights on the jeep has 125000

[4.3LXJ]

Champion copper plugs. Yes they can run like crap with the wrong plugs. It is an old school motor with fuel injection hung on it. They just don't like hot plugs

[william]

Champion copper plugs. Yes they can run like crap with the wrong plugs. It is an old school motor with fuel injection hung on it. They just don't like hot plugs

Ok ill get some in the morning and head up to work and change them ill keep you posted thanks for your help

[Cheromaniac]

i picked up a 99 cherokee first cherokee heres my problem the jeep starts and runs but it acts like its misfiring i pulled the wires and they all seem to be firing. ive read a few forms and some said the head gasket goes bad and can cause it to run like crap but theres no antifreeze comin out the tail pipe just smells like gas so im thinking the valves are messed up but im really not sure does anyone know how to tell if its a head gasket or the valves are not working right ? i just dont want to pull it all apart and find out i need a head if anyone can point me in a direction i would be your friend till the end lol :bang::bang:

Firstly replace the distributor cap, rotor, plug wires, and plugs (stock Champion Copper Core). If that doesn't help, visit your local autozone and ask for a free code scan. If you have a faulty sensor the ECU will store a code.
You can also do a compression test (dry & wet) on all cylinders to see if there's any compression loss through a bad head gasket, valves, or piston rings.
All of the above are simple, cheap, and I'd be surprised if none of those measures reveals where the problem lies. Let us know how you get on.

[william]

Ok ill get some in the morning and head up to work and change them ill keep you posted thanks for your help

So i put champion coppers in and runs alittle better but still shakes. The d bag at the parts store said its the pick up coil then went on about how he had 3 cherokees and it don't matter what plugs, he was tryin to make me buy all eridium plugs and a pick up coil. Id rather ask someone on here cuz that guy was a tool. :confused:

[nickyg]

"HAD 3 Cherokees"???.. That's your first clue he was a tool... If he really had 3 cherokees he would still own at least 2... I feel your pain brother, I hate going to the auto parts store.

[4.3LXJ]

Iridium is an element that they coat plugs to make them last longer nowadays. It is not necessary for a 4.0. Glad there was some improvement. I think some sea foam in the gas will help a little too by cleaning out the injectors a little.

[william]

Iridium is an element that they coat plugs to make them last longer nowadays. It is not necessary for a 4.0. Glad there was some improvement. I think some sea foam in the gas will help a little too by cleaning out the injectors a little.

I get paid at the end of the week ill pick some up and try it out. Its just crazy no check engine light and i hooked the snap on scaner to it and nothing came up thats why I'm lost lol

[4.3LXJ]

Things like dirty injectors and worn valves will not show up on a scanner. Just the electronic stuff. Put the sea foam in about a 1/4 tank and take it for a nice drive and drive most of it out before filling up

[william]

Things like dirty injectors and worn valves will not show up on a scanner. Just the electronic stuff. Put the sea foam in about a 1/4 tank and take it for a nice drive and drive most of it out before filling up

Ok ill try it thanks again

[william]

Update ok so i hooked the comp gage up and 3&4 are dead. I was wondering when i pull the head do i need new head bolts? ?? Ill be doin the head gasket at the end of the month do to my baby shower first baby she will be here may 16th so i hope i can get the jeep staight before she gets here. :D

[Mudderoy]

So i put champion coppers in and runs alittle better but still shakes. The d bag at the parts store said its the pick up coil then went on about how he had 3 cherokees and it don't matter what plugs, he was tryin to make me buy all eridium plugs and a pick up coil. Id rather ask someone on here cuz that guy was a tool. :confused:

If you don't have any codes, I'd do a compression test.

A bad sensor could cause this problem. A dirty throttle body, and/or dirty idle air controller.

[Mudderoy]

Update ok so i hooked the comp gage up and 3&4 are dead. I was wondering when i pull the head do i need new head bolts? ?? Ill be doin the head gasket at the end of the month do to my baby shower first baby she will be here may 16th so i hope i can get the jeep staight before she gets here. :D

Sorry just read this post. Damn that's too bad. Head bolts on the 4.0 are 2 use. Once from the factory and one more time, then you have to replace.

[william]

Sorry just read this post. Damn that's too bad. Head bolts on the 4.0 are 2 use. Once from the factory and one more time, then you have to replace.

Ok thanks for the info, its got a freeze plug leakin behind the fly wheel not sure what one yet would you happen to know the size of the freeze plug or is there a kit for the 4.0?

[grainofsalt]

Freeze plug kit: http://www.summitracing.com/parts/rnb-567-017/overview/make/jeep

How to: http://go.jeep-xj.info/HowtoWelshPlugs1.htm

[grainofsalt]

Just received that freeze plug kit in the mail, It has 4 of the 2" and one 2 1/16" freeze plug.

To complete the job you are going to need 2 more 2" plugs, B/C there are 5 2" on the side of the block 1 on the head and the 2 1/16" is in the back behind the flywheel.

[william]

ok heres my update since i fell off earth lol i pulled the motor changed all of the freeze plugs cuz the one behind the fly wheel had a hole . the misfire was a half inch break in the head gasket inbetween #3-#4 cylinder cleaned it all up slapped a new head gasket in dropped the motor back in last thursday fired it up and runs great. the peorson before me must of thought the convertor was pluged cuz they cut it off and didnt put the o2 back in so my check engine lights on but ill fix that . thanks everyone for your help on my first jeep

[william]

I got the same kit i had to pick up 3 more 2 inch figured its out better chenge them all knowin my luck if i didnt one would blow out after the motor was back in lol thanks for your help

[nickyg]

first baby she will be here may 16th so i hope i can get the jeep staight before she gets here. :D

Congrats on a smooth running Jeep. How's that baby coming along? (the one without a steering wheel) we expect to see pics of both.

[william]

She's dew may 16th can't wait lol thanks for askin. :)