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Old 11-10-2013, 02:48 PM   #1
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constant engine misfiring issue ?

i just changed my pugs and boots last weekend because it was misfiring(ticking noise) got a couple days with no noise and now it keeps on misfiring. anybody know what else it could be?
thanks in advance
joe

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Old 11-10-2013, 02:58 PM   #2
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Check Engine light? Codes?

Exactly what spark plug brand & model # was in it before, and exactly what spark plug brand & model # did you just install?

I'm kinda leaning towards an 02 sensor problem but the wrong type of spark plug can cause misfires too... even if the guide book blesses them. Even Autolite has a bad recommendation in their spark plug guide for 2000 and newer TJ 4.0L engines so you can't always trust everything you read.

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Old 11-10-2013, 03:04 PM   #3
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No check engine lights or codes. I put in the champion spark plugs and I believe that is what was in previously as well.
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Old 11-10-2013, 03:06 PM   #4
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I was wrong... it was auto lite that I just installed. It was auto lite that was used previously too. Sorry about the mid information
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Old 11-10-2013, 03:10 PM   #5
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Ok, Autolites... as was asked, exactly what model Autolite spark plugs did you install? 985? AP985? APP985? XP985?
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Old 11-10-2013, 04:56 PM   #6
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They were the AP985
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Old 11-10-2013, 05:02 PM   #7
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AP985 is a single-tipped platinum plug which is the wrong model for 2000 and newer TJs with the distributorless ignition. It can and does cause mysterious idles and can cause misfiring in the newer distributorless 4.0l engine. The 985, APP985, and XP985 are appropriate for newer 4.0L engines like yours. The 985 will perform well for 25-35k miles, the APP985 around 100k miles, and the XP985 probably at least 200k miles.

I'm not guaranteeing replacing that AP985 is the cure for your current misfiring but eventually, that AP985 will start causing problems.
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Old 11-10-2013, 05:24 PM   #8
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Thanks
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Old 11-18-2013, 08:27 AM   #9
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i just replaced the ap985 spark plugs with the app985 as recommended. its been 3 days or so since i replaced the plugs and it is misfiring(ticking) again. when i listened to it, it sounds like it is coming from the middle of the coil rail. any other ideas for what it might be?

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