Help please Re: Misfires

soulpunisher

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2003 Jeep Liberty limited 4x4 I recently redid my valve cover gasket’s, then my entire fuel system (gas tank, fuel pump/sending unit, fuel filters, fuel injectors, fuel relays/fuses etc) then I did all my spark plugs and coil packs and she ran like a champ, perfect idle and running no misfires. 2 days later started the jeep and now I get a misfires on cylinders 3 and 6! Can’t get them to go away, but when I pull the plugs and coil packs and test the spark they are inconsistent on sparking as well as the color they arc is orange colored??
Is this my wiring? My ecm? Or all of it or something else?
 

02blue

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Might be tough to tell from the arc if things are good enough. What brand plugs and coil packs did you use? Did you check the gaps on the plugs? Pre-gapped isn't always correct. Have you swapped the #3 and #6 cylinder coil packs to a different location or put an old working one back in those locations? That would eliminate the possibility of a bad coil pack. Could be injector too if you did all that part replacement and knocked some crud loose to find those injectors.
 

soulpunisher

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I bought quality brands (I normally always do) and I ALWAYS gap them myself and I’ve already swapped them with each other and with other ones next to them, same problem. I’ve already trouble shooted every other possible method recommended,thus far. According to everything I’ve seen and heard every arc for all plugs should be blue not orange? Please correct me if I’m wrong? But yes, gapping, brand and testing every other method has already been done several times and also by other people as well, still the same problem yet it ran perfectly just a few days ago.
 

02blue

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Arc color is a questionable test. Not sure color really tells you much since other factors can affect color other than pulse strength. As long as they are arcing (#3 and #6 as well as the others) I'd be happy since the PCM is triggering them and it's not a major PCM/electrical issue. You can unplug the PCM and plug it back in but I doubt that's the issue. I'd disconnect the battery first but that's just the way I roll. Seems likely some new part isn't playing well with the others. Fuel injectors or maybe even fuel pressure? Even though it's the same two cylinders maybe some weirdness in the new injectors are aggravating those two.
 

soulpunisher

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I didn’t mention and should have, that also other things are happening that are giving narrowing signs. Such as, the dash lights sometimes flicker but have already installed new bulbs in it not even a year ago, and things like the doors unlock and lock during the entire time you drive (long or short distances) plus I just now got all codes to clear earlier today and after 30 mins of drive time and parked again and waited 2 hours both cylinders are miss firing again! I can’t think of what else it would be because I’m getting good spark when it is good, good air and perfect gas I’ve tested the gas pressure on the fuel rail several times with a gauged tester kit.
 

DadOSix

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I didn’t mention and should have, that also other things are happening that are giving narrowing signs. Such as, the dash lights sometimes flicker but have already installed new bulbs in it not even a year ago, and things like the doors unlock and lock during the entire time you drive (long or short distances) plus I just now got all codes to clear earlier today and after 30 mins of drive time and parked again and waited 2 hours both cylinders are miss firing again! I can’t think of what else it would be because I’m getting good spark when it is good, good air and perfect gas I’ve tested the gas pressure on the fuel rail several times with a gauged tester kit.
What kind of codes are you seeing?
 

tommudd

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I bought quality brands (I normally always do) and I ALWAYS gap them myself

but what brand ?
Maybe quality to you BUT some brands just do not work on these KJs
spark plugs NGK copper only for example
 

LibertyTC

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These are the correct spark plugs for the KJ.
You must be registered for see images attach
 

soulpunisher

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They’re both ngk but I’m unsure if they’re copper spark plugs, they’re ngk v power
 

LibertyTC

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Jeep spent much time testing spark plugs for the KJ & they fire those NGK ZFR6F-11G plugs hot. (good)...
I would stay with the factory recommendations.
 

DadOSix

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I didn’t mention and should have, that also other things are happening that are giving narrowing signs.


Such as, the dash lights sometimes flicker but have already installed new bulbs in it not even a year ago, and things like the doors unlock and lock during the entire time you drive (long or short distances)
Thinking out loud: all these things are pointing to electrical issues -

Flickering. Random lock unlock. - maybe BCM - but -- i think not.

1 - decent system voltage? How old is your battery? Clean terminals? Hard to start ?

2 - check body and engine grounds. Starting from the battery and working rear-ward. There is the big engine ground, a few smaller grounds that pull from the negative battery and are near the PDC (fuse box)
- engine grounds back of head to firewall.


plus I just now got all codes to clear earlier today and after 30 mins of drive time and parked again and waited 2 hours both cylinders are miss firing again! I can’t think of what else it would be because I’m getting good spark when it is good, good air and perfect gas I’ve tested the gas pressure on the fuel rail several times with a gauged tester kit.
 

02blue

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^^^^THIS

Both of mine did weird things (like you're seeing) when battery was getting flaky. Sometime just cleaning the terminal connectors helped. One time with my 02 I couldn't even tell by looking. Cleaned them anyway and slapped a little dielectric grease on and all better.
 

soulpunisher

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Update* I do have a brand new battery already and also redid my terminal connectors before all of this, so I know all of that was good. I just now swapped my ecm etc (computer) and yes I had it bought new and programmed properly at a dealership and just like magic no more misfires at all anymore but I am still having the doors locking and unlocking problem. Going to check my ground wires tomorrow and if they’re ok but still same problem I’m gonna check my wiring in my doors etc as well as check my fuses that are for those things.
 

DadOSix

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Update* I do have a brand new battery already and also redid my terminal connectors before all of this, so I know all of that was good. I just now swapped my ecm etc (computer) and yes I had it bought new and programmed properly at a dealership and just like magic no more misfires at all anymore but I am still having the doors locking and unlocking problem. Going to check my ground wires tomorrow and if they’re ok but still same problem I’m gonna check my wiring in my doors etc as well as check my fuses that are for those things.
Great job!
 

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