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Big Gus 07-14-2007 07:12 PM

Help with 82 CJ 258 missfiring
I need help trouble shooting. I have an 82 CJ7, 4.2 (258).
Replaced the worn cam and put new lifters in about 8000 miles ago, and while I was at it replaced the timing chain. It has ran fine until yesterday, and it has started spitting and back firing thru the intake, badly!
I have checked the spark advance mechanism, working, checked for vacum leaks, none, put a rebuilt carb on it when I replaced the cam, never had a lick of trouble from it. It is alsost acting like it threw a tooth on the timing chain (or the cam went bad). I was told that a coil can go bad and cause these symptons also. Before I tear into it , I would like some suggestions. Thank You!

debruins 07-14-2007 08:13 PM

a coil is easy to fix, buy a new one for like $40

i woould ask here though
they know their stuff

Big Gus 07-15-2007 08:16 AM

Distributer cap, rotor??
Could a bad distributer cap or rotor cause a backfire thru the intake??
Just want to explore the cheaper options first.

debruins 07-15-2007 09:52 AM

well a backfire through the intake is kinda of a common thing, you probably have a rich mix, i believe, but again i would ask over at ecj5.
Do this, pull your plugs, clean them real good, then replace them, run the engine for two minutes, through all RPM's. let the engine cool down, take out the plugs and look at them, if they have lots of ash your runnning rich, actually they really shouldnt have any ash on them

that will tell you if your running rich, then i owuld put a ai cleaner on it, b/c you shouldnt run an engine wihthout one, and i assume you dont have one b/c then you wouldnt even notice the backfire.

once again not an expert at these carb adjustment and timing adjustment things so i would ask at ecj5 forum

Big Gus 07-15-2007 10:22 AM

No way it's a carburation issue. It is popping and spitting too much for that, almost like the cam has gone bad, or timing chain. I can't see this though, since it's only been 8000 miles since both were replaced.
It does idle smoothly, a little backfire, then when accelerating it reaaly starts to spit and pop back thru the intake and carb

debruins 07-15-2007 10:54 AM

hmm cam problmes sounds plausible, if the vqalves arent shutting all the way, umm i have no idea wha to do about that

if u havent gotten the drift, ask here

penguin_in_a_cj 07-16-2007 11:42 AM

something to think about is an hei upgrade for your jeep. you can put a diffrent distributor in with a cam gear out of something else I got to find the link somewhere in my pile of websites. I will put if up for you later. makes a big diffrence.

penguin_in_a_cj 07-16-2007 11:44 AM

sorry I forgot to put the main thought into that make sure your distributor is not worn out. sounds like the problem I had with mine. if it is youll have play alot of it

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