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Odd cylinder 1 Misfire...

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Old 06-25-2011, 09:21 PM
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Default Odd cylinder 1 Misfire...

96 Jeep Cherokee 4.0 Auto. The CEL was on so I scanned it and said Cylinder 1 Misfire. So I replaced the fuel injector with no change. It has 13.xx volts going in on one side of the plug. It has spark with new plugs, wires, Cap and rotor. When I take the clip off it doesn't change the idle like the rest of them do... any Ideas? If you need more Info let me know thanks.
Old 06-25-2011, 09:42 PM
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Originally Posted by JoshMan88
96 Jeep Cherokee 4.0 Auto. The CEL was on so I scanned it and said Cylinder 1 Misfire. So I replaced the fuel injector with no change. It has 13.xx volts going in on one side of the plug. It has spark with new plugs, wires, Cap and rotor. When I take the clip off it doesn't change the idle like the rest of them do... any Ideas? If you need more Info let me know thanks.
Wow not too sure on this one, but check the fuel rail, maybe there is somethin in it

have you pulled the injectors out and see if they fire?
Old 06-25-2011, 09:45 PM
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When I was replacing the #1 injector I forgot to do that. But I did swap #1 injector plug onto another injector and it worked... just can't figure out why that one cylinder/new injector is being a pain in the @$%.
Old 06-25-2011, 09:53 PM
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Maybe its a bad injector, sometimes you just don't know with China
haha
this guy had a similar problem:
https://www.cherokeeforum.com/f2/199...ed-help-64824/

Last edited by Cherokee89sport; 06-25-2011 at 10:02 PM.
Old 06-25-2011, 10:22 PM
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yeah the box said Made in USA so I think I'm good (atleast the box was made in America lol) and I read pretty much all of those and Haven't found a good answer. I also Don't feel like pulling off my Heads lol
Old 06-25-2011, 10:22 PM
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Had the same issue. Replaced injector twice. Switched injectors around, still had the issue. Finally checked the harness. Had a melted wire that was shorting out.
Old 06-25-2011, 10:25 PM
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Yeah, I was going to check that next. But I checked for Voltage and it said 13.xx and I dont think my meter is good enough to check for the impulse on the other wire...
Old 06-25-2011, 10:34 PM
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Did you do a Compression test on #1 cylinder? May have a valve issue. You can get a set of noid lights pretty cheap, these will test the injector circuit also.
Old 06-25-2011, 10:40 PM
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Rent a noid light frpm autozone. Disconnect injector harness from wire and plug light into the harness. Start up your jeep and watch the light. It should blink consistantly. Mine was erraticwhich led me to inspect the wiring. Ohm meter showed no shortage in the wire. I guess it was only occurring while the vehicle was on.
Old 06-25-2011, 10:57 PM
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Yeah I'm going to do a compression test tomorrow. I just tried the Noid light on the plug and one side lights up (steady) other side It doesn't blink or nothing. I also did more then one injector and all the same. Maybe a cheap light? lol
Old 06-25-2011, 11:00 PM
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I also didn't use that noid light, Thinking of something different. I used a test light...maybe thats why?
Old 06-26-2011, 01:49 AM
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The circuit fires too fast for a test light, thus the constant on appearance. Try the noid light set from autozone. The rentals only require a deposit, which you get back when you return the set.
Old 06-26-2011, 02:23 AM
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yeah, I'm going to do the compression test first. that will tell me if i should even mess with the damn injector or not haha. Hoping I don't have a cracked head
Old 06-26-2011, 05:43 AM
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Compression test never a bad idea, but simple stuff first.

New plug, new plug wire, new distributor cap. Any one of those could be marginal enough to create a misfire.
Old 06-26-2011, 11:20 AM
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Just Did a full tune up less then a week ago with: plugs, wires, cap, rotor, oil change, fuel filter.


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