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MJ Misfiring on #1 ??


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I unplugged the leads 1 by 1 and everyone i unplugged the idle changed significantly except for #1 when i unplugged the lead from the spark plug there was no big change in idle theres spark coming from the lead when i unplug it but funny thing is it sounds fine idling to me but then again what do i know ive never owned a jeep before truck seems to run fine i don't feel any lack of power or anything but like i said i have never owned a jeep before so don't know what its suppose to feel like  i have new plugs in there new leads,,tomorrow i'm going to check the compression but any ideas from you guys are always appreciated maybe a comon problem or anyone whos had the same issue before input is most welcome..

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Do you have a check engine light flashing or a code or something specifically stating engine miss fire? Or are you just assuming because there was no change in idle when you unplugged the front plug?

OP has an 89.  Pre OBD.  No flashing lights or codes.

 

Only way I am aware he could get computer info is from a SnapOn MT2500 or similar scanner.

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Do you have a check engine light flashing or a code or something specifically stating engine miss fire? Or are you just assuming because there was no change in idle when you unplugged the front plug?

 

OP has an 89.  Pre OBD.  No flashing lights or codes.

 

Only way I am aware he could get computer info is from a SnapOn MT2500 or similar scanner.

  

Do you have a check engine light flashing or a code or something specifically stating engine miss fire? Or are you just assuming because there was no change in idle when you unplugged the front plug?

Yeah it's an 89 no lights I just assumed since there was no change in the idle when I unplugged #1 cylinder there might be a problem with it cause all the others #2-#6 cause a rough idle when unplugged

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Do you have a check engine light flashing or a code or something specifically stating engine miss fire? Or are you just assuming because there was no change in idle when you unplugged the front plug?

OP has an 89. Pre OBD. No flashing lights or codes.

 

Only way I am aware he could get computer info is from a SnapOn MT2500 or similar scanner.

.

 

Wasn't sure what year he had, that's why I listed some explanatory questions.

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You can use a inferred thermostat and point it at each exhaust tube coming right off the head and you will see if there are any inconsistency in temp. That is a great tool to have anyway.  I bet there is not a problem. I think I remember noticing the same thing once when I pulled number 1 for something I was doing on my Cherokee. probably just not real noticeable at idle.

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You can use a inferred thermostat and point it at each exhaust tube coming right off the head and you will see if there are any inconsistency in temp. That is a great tool to have anyway.  I bet there is not a problem. I think I remember noticing the same thing once when I pulled number 1 for something I was doing on my Cherokee. probably just not real noticeable at idle.

 

 

 

Bad injector?

 

Pull the plug out and see if it's wet or dry........

that would be my second idea

 

 

 

Bad injector? 

 

Pull the plug out and see if it's wet or dry........

 

 

 

dumb question, you say ou put all new plugs in, are they gapped correctly? could 1 be miss gapped?

^this....

Or either a bad plug/wire...

 

 

 

Did you do the compression test?  What were the readings across the engine?  Does #1 have a leak?

 

So found the culprit did a compression test this morning on all cylinders 150 across the board which i'm assuming is good compression?!?...anyway when i took out #1 plug i noticed there was no carbon build up on there was almost as new as when i put it in where as all the other plugs had a little black on the tips so i thought maybe it was the plug or lead or something so connected the the plug and swung the engine with the plug out gave me a good zap so plug was good so my next bet was the injector just as Cruiser said so pulled it out and it so happened that the oring ging into the fuel rail maybe had dry rot and pieces of it broke of and apparently chocked the injector took it out cleaned it up when to the parts store picked up a set of new fel pro o-rings for 5 bucks put it back in and damn i never heard this truck idle so beautifully and just when i thought it was already idling good but like i said what do i know never owned a jeep before just glad that i did have to end up opening that engine ..anyway thanks again for ur input guys much appreciated

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You can use a inferred thermostat and point it at each exhaust tube coming right off the head and you will see if there are any inconsistency in temp. That is a great tool to have anyway.  I bet there is not a problem. I think I remember noticing the same thing once when I pulled number 1 for something I was doing on my Cherokee. probably just not real noticeable at idle.

 

 

 

Bad injector?

 

Pull the plug out and see if it's wet or dry........

that would be my second idea

 

 

 

Bad injector? 

 

Pull the plug out and see if it's wet or dry........

 

 

 

dumb question, you say ou put all new plugs in, are they gapped correctly? could 1 be miss gapped?

^this....

Or either a bad plug/wire...

 

 

 

Did you do the compression test?  What were the readings across the engine?  Does #1 have a leak?

 

So found the culprit did a compression test this morning on all cylinders 150 across the board which i'm assuming is good compression?!?...anyway when i took out #1 plug i noticed there was no carbon build up on there was almost as new as when i put it in where as all the other plugs had a little black on the tips so i thought maybe it was the plug or lead or something so connected the the plug and swung the engine with the plug out gave me a good zap so plug was good so my next bet was the injector just as Cruiser said so pulled it out and it so happened that the oring ging into the fuel rail maybe had dry rot and pieces of it broke of and apparently chocked the injector took it out cleaned it up when to the parts store picked up a set of new fel pro o-rings for 5 bucks put it back in and damn i never heard this truck idle so beautifully and just when i thought it was already idling good but like i said what do i know never owned a jeep before just glad that i did have to end up opening that engine ..anyway thanks again for ur input guys much appreciated

 

Woohoo!! Thanks for reporting back.

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