Wrong Spark Plug?
01-16-2016, 12:56 AM
#1
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Wrong Spark Plug?
I decided to change my spark plugs tonight since I was getting a misfire in cylinder 1. I got the champion copper RC12LYC and gapped them to about .040. After changing them and starting it up, it idled roughly and was backfiring every few seconds. I got to looking at the old spark plugs and they were Champion Copper RC12PEC5!! Also they had been gapped to about .085 or .090?!?!? I took the new plugs off and gapped them to match the old ones. Still had the issue. I cant put the old ones on because I cracked a couple of them while pulling them out. I dont know what is going on and could really use some advice here.
01-16-2016, 01:49 AM
#2
Old fart with a wrench
What is your year and engine?
93-98 4.0 Champion RC12LYC (.035")
99-03 4.0 Champion RC12ECC (.035")
04 4.0 NGK ZFR5N (.040")
If it's a V8, let us know which one.
93-98 4.0 Champion RC12LYC (.035")
99-03 4.0 Champion RC12ECC (.035")
04 4.0 NGK ZFR5N (.040")
If it's a V8, let us know which one.
01-16-2016, 01:50 AM
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01-16-2016, 01:59 AM
#4
Old fart with a wrench
Your old plugs were probably worn to .080-.090, that's not unusual. Your misfire may have been caused by carbon build-up on the valves or the large gap on the plugs.
Just as a point of reference, I'm running NGK ZFR5N in my 2000 4.0 and they are fine. I put those in after a Champion cracked an insulator tip. So far, so good.
Just as a point of reference, I'm running NGK ZFR5N in my 2000 4.0 and they are fine. I put those in after a Champion cracked an insulator tip. So far, so good.
01-16-2016, 02:01 AM
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Your old plugs were probably worn to .080-.090, that's not unusual. Your misfire may have been caused by carbon build-up on the valves or the large gap on the plugs.
Just as a point of reference, I'm running NGK ZFR5N in my 2000 4.0 and they are fine. I put those in after a Champion cracked an insulator tip. So far, so good.
Just as a point of reference, I'm running NGK ZFR5N in my 2000 4.0 and they are fine. I put those in after a Champion cracked an insulator tip. So far, so good.
01-16-2016, 02:06 AM
#6
Old fart with a wrench
I've used Champion plugs in Mopars for a long time and never had problems with them, but lately their quality sucks. It's not unusual to find cracked insulators on them. My faith has been shattered!
Try the NGK's. They are actually cheaper.
Try the NGK's. They are actually cheaper.
01-16-2016, 02:07 AM
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Well if thats the case, should I try NGK and cross my fingers. I might throw new plug wires on too just to be safe
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01-16-2016, 02:10 AM
#8
Old fart with a wrench
We crossed posts! I just edited my last! Wires may be a good idea as well. Check your cap and rotor.
01-16-2016, 09:57 AM
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Well I got to looking at my plug wires and some of the clips that go in the spark plug were missing? Probably pulled off while I was taking out the new plugs im guessing. I put on new plugs and new wires but now I have a new problem. Pretty sure I fried my ecu
https://www.cherokeeforum.com/f5/pro...8/#post3199613
https://www.cherokeeforum.com/f5/pro...8/#post3199613
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