beach dude

hello all! great site ya got here. this is my 1st post here and im looking for some help.

got a 2000 cherokee with the check engine light on. my buddy has a diagnostic machine and its telling us that cylinder 3 is misfiring. ive already read a little online here and from what i understand (no mechanic here by any means), the heat from the exhaust is migrating up the engine block (when vehicle is off) to the injector line and causing the fuel to boil thus causing the misfire. ok so ive read that there is a heat sheild that can be installed, which i already think there is one (as i bought used) so that shouldnt be the problem. changed the plugs and coil already. still the light came back on after being cleared. i just talked to a service guy at the jeep dealer and he was telling me to check compression. what is the easiest way to check engine compression on my truck?? has anyone ever had these symptoms before? thanks in advance guys/girls!!

beach dude

anybody have a fix for this? been reading around and either no one has posted a reply for a fix or there aint one. getting real sick of the light coming on. thinking of selling the jeep cause of it. i'd rather not but if there is no fix i dont wanna every month with it. thanks again!

muddeprived

Oh....normally I run away from these threads cuz I'm going through the same thing and it's just a BIG headache.

Here are some good reads that will explain everything and possible fixes:

http://www.cherokeetalk.com/forum/f2...-misfire-6800/

http://www.naxja.org/forum/showthread.php?t=1009745

Abovetimberline

If you have good compression,spark,fuel supply,consistently,it will not misfire,I would check compression,remove your coil packs in order to get to the plugs and remove them,check #3 with a compression guage and see where it is,should be at least 100lbs,normal is 120-150lbs,the correct procedure is a bit more complicated,but for what you are trying to find out it will work just fine,if it has good compression,it gets a bit harder because it could be a sticky valve,injector going bad,or wiring to the coil or injector.

beach dude

wow thanks man! thats some good reading there! any luck with the heat tape wrap job? looks like you did a good job there!

(Eckks-Jay)

I used spark plug insulators on all six of my injectors on my 2001 for the cyl 3 misfire. looks great and factory like...might check that out. they sale them at just about any auto parts store.

muddeprived

I dunno yet. I haven't driven it far to see if it worked but I'm doubting it. I drove it to UPS and it stumbled a little when I started it up. It wasn't anything like the usual misfire but it wasn't a normal start up either. My next possible fix is to remove to intake manifold and wrap the headers and put a heat shield UNDER the manifold. This will be my last step and if it don't work I swear i'm tearing out the engine.......

beach dude

i think thats the issue. is fuel. the heat soak causes it to turn to vapor in the injector line

so how long since you put them on have you not had a problem?

thats what im afraid of. i really think thats overboard for a stupid heat soak issue. i mean if it works then great but in my eye its just uncalled for to do that much work for this rediculous problem! ! !

beach dude

anybody??

beach dude

anybody ever try ceramic coated headers? just trying to throw out ideas!

petesxj

i dd what that bulletin sais to do and my heat soak problem went away. If you continue you to have this problem i would try heat wrap the header

petesxj

^^^^^ wow txting and typing at the same = bad idea ^^^^^

beach dude

which bulletin are you talking about?

GhostRider

I really cannot understand how the fuel can boil/vaporize in the injector.
All the injectors are tied to a common fuel rail. The fuel is being pump through the fuel rail under pressure. It sounds more like a bad injector or a leaking (o-rings) injector that is making that particular cylinder run very lean, this will also create a lot of heat in that cylinder. Once you start having injector problems, it's probably better to replace all the injectors. If you chose to replace the injectors, look on Ebay for a set of reconditioned Mustang GT 5.0 injectors. They have 4 holes in the end of the injector that better vaporizes the fuel and actually increases HP. These are ultrasonically cleaned and matched for volume output. They will also come with new o-rings. A complete set for $115 to $125.
I had an injector that was leaking down and a new replacement was $75 to $100. Good Luck!

petesxj

the bulletin on putting a plug wire insulator over the inj. Replacing the injectors to bigger ones is a waste, there not doing anything different than the stock ones are doing the ecu is going to adapt rhe fuel map. The only time bigger injectors does anything is with a ton of bolt ons that forces a tune that maxes out the duty cycle of the factory injectors. Feeling more power is all in your head bigger injectors doesn"t add power.