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Unread 01-15-2006, 04:00 PM   #1
willy peter
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Misfiring 4.0

I already posted this in the TJ forum, but I thought I might get more/better responses here. So for about the last week I've had the check engine light on telling me that cylinder #5 is misfiring. It would only happen under real heavy acceleration. Well, Friday the 13th comes around and guess what, it know does it constantly and my jeep is undriveable. I believe it may be clogged or dirty injectors from a bad tank of gas. I will be replacing them ASAP. Has anyone else had this problem and/or do you think this will fix it. BTW, only 32K miles.

Plugs were replaced 2K ago with champion truck plugs. There are no plug wires on a 2001. I think I can rule out any spark related problems.

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Unread 01-15-2006, 04:32 PM   #2
Matt Gertsch
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Its a pretty common problem on the 00-01 XJs too. Call the dealership and see if you have any outstanding recalls. There was a heatshield recall on the XJs.
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Unread 01-15-2006, 05:15 PM   #3
bobjp
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What makes you think you got a bad tank of gas? That would effect all of the cylenders not just number 5 I would think.
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Unread 01-15-2006, 08:05 PM   #4
willy peter
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Quote:
Originally Posted by mgertsch
Its a pretty common problem on the 00-01 XJs too. Call the dealership and see if you have any outstanding recalls. There was a heatshield recall on the XJs.
I have heard about adding additional sheilding to the #3 injector but not #5.
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Unread 01-15-2006, 08:07 PM   #5
willy peter
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Quote:
Originally Posted by bobjp
What makes you think you got a bad tank of gas? That would effect all of the cylenders not just number 5 I would think.
I have friend who got gas from the same place about the same time and his car wouldn't start until he diluted it with a lot of new/different gas. Unfortunate he only got about 5 gallons whereas I got 15. I think it started with #5 but will spread to all of them eventually.
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Unread 01-15-2006, 08:43 PM   #6
bobjp
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Have you tried diluting your gas? Or maybe drain it out and putting some new gas in. Check out your fuel filter. See if it is filled with gunk; if it is then it may have let stuff pass into your injectors. There are products that you can buy that will clean your injectors. I used some stuff from napa that came in an aerosol can. You spray it right in the injectors when you take them off.

I am unfamiliar with the ignition system of a 2001 4.0. You say it doesn't have plug wires? What kind of ignition system does it have? Do you have a chiltons/haynes manual for it. I have a Haynes manual for 87-2003 wranglers and it doesn't say anything about the 2001's not having plug wires otherwise I would look in it for some info for you.
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Unread 01-15-2006, 09:18 PM   #7
Snuffster
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Quote:
Originally Posted by bobjp
What kind of ignition system does it have? Do you have a chiltons/haynes manual for it. I have a Haynes manual for 87-2003 wranglers and it doesn't say anything about the 2001's not having plug wires otherwise I would look in it for some info for you.
'00's and up use a coil pack ignition system (much better when you blast through water lol). The problem could be a bad coil pack. They do go bad. It is easy to test, but too much for me to type. I will say you need an ignition system tester, a jumper wire and you have to remove the coil rail. A Haynes manual details it step by step. I think bad gas is out of the question.
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Unread 01-15-2006, 09:21 PM   #8
willy peter
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Quote:
Originally Posted by Snuffster
'00's and up use a coil pack ignition system (much better when you blast through water lol). The problem could be a bad coil pack. They do go bad. It is easy to test, but too much for me to type. I will say you need an ignition system tester, a jumper wire and you have to remove the coil rail. A Haynes manual details it step by step. I think bad gas is out of the question.
I will look into that, is it common for them to fail this soon?
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Planning on more, just saving up the cash.
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Unread 01-15-2006, 09:29 PM   #9
Snuffster
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*edit* Nevermind, you know you have a #5 misfire. I'm betting it's a bad coil pack or injector.
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Unread 01-15-2006, 09:31 PM   #10
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Quote:
Originally Posted by willy peter
I will look into that, is it common for them to fail this soon?
I don't know if it's common, but it is not unrealistic.
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Unread 01-15-2006, 09:45 PM   #11
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One option is to swap the #5 injector with another one and see if the same cylinder is misfiring. If not, switch coil packs around.
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Unread 01-16-2006, 02:53 PM   #12
willy peter
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OK, I got a new injector to try, but now I'm trying to reinstall the fuel rail. I can get all of the injectors to fit snug in either the manifold or the rail, but none of them will snap into both the manifold AND the rail. I have lubed all the o-rings, and applied superhuman strength. What else do I have to do?
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D44/D30 with 3.73's/31x10.5 Kumho AT's on stock canyon's/Rhino-lined interior/Alpine 9856 Headunit with Infinity speakers/Teraflex disco's/Blacked out headlight bezels/Removed front flotation devices!
Planning on more, just saving up the cash.
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Unread 01-25-2006, 11:42 PM   #13
stonehogg
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How Come Your Engine Light Is So Smart It Can Tell You Which Cylinder Is Misfiring ? No Body Elses Is....
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Unread 02-03-2006, 08:51 AM   #14
WVMIKEsTJ
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Same prob!

Mine is doing it to!! I changed plugs and that worked for a few days and then poof the light was back on. Went to the dealer and the mechanic told me and showed me that # 5 is misfiring. I was watchiong it misfire on their computer. What next?
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Unread 02-03-2006, 10:37 AM   #15
98JEEPTJ
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I have a stupid question for you guys. Are you using the correct plugs?? Are you sure you got the correct plugs from the parts store. I had a dude give me five correct plugs and one that was to long. Thus the piston hit the plug just enough to bend over the electrode so it wouldn't fire. it was cylider #5. I couldn't figure it out until I pulled all the plugs and was inspecting them and see this one all bent and mangled. I was pissed. The dude at oreillys just said oops. So I talked to the manager and he paid for the Shop to look at the pistons and head to make sure there was no damage...I was pretty scared when he said that they had bought people engines in the past because they gave them the wrong parts...Yeah I don't go to that store any more....
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