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XJ Rail Sale!The Ruffstuff NOT Universal 4 Link Kit!Vanco Big Brake Kit Promotion!

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Unread 02-15-2011, 08:20 PM   #1
lovemy3
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Wj Codes P0303 & P0304

New to the jeep world and just need alittle help.....
Just brought a 1999 Jeep Cherokee Laredo 4.0...Changed the plugs & coil pack but still has ruff idol. Any ideas where to go next?
Any help would be appreciated. Thanks in advance


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Unread 02-15-2011, 09:35 PM   #2
oakmckinley
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Those codes are for a cylinder misfire in #3 and 4. There is a heat soak problem that happens and can cause cylinder misfire. There a some threads on this. I think there is something you can buy that insulates it.
Good luck.
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Unread 02-15-2011, 09:39 PM   #3
WhiteMtnJeep
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I had this problem in the past. Read this post.

http://www.jeepforum.com/forum/f9/03...en-hot-607283/
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Unread 02-15-2011, 11:32 PM   #4
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I have the p0304 at all times, not just when the engine is hot. I have new plugs and coil rail also. The next thing I'm replacing is the injector on that cylinder. I'm hoping it fixes it. If not, I'm gonna put a match to it lol... I have also read that it could be the gapping on the plugs, fuel filter, the heatsink issue(you should have a heatmat on the top of the intake in between the injectors and the intake itself), and you may also want to clean the throttle body. My bet would be fuel injectors are probably clogged or have gunk in them. Have you ran any fuel injector cleaner lately?
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Unread 02-16-2011, 08:54 AM   #5
lovemy3
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Thanks everyone for your help. Yes Ive ran (1) bottle of injector cleaner and have another in the jeep to run. I was talking with a guy last night at autozone...(one that seemed like he knew alittle..not like most there) said he would test pressure of injectors first then go from there. Thanks everyone for the links to all the fourms..I've did alittle bit of reading and it's helped.

Sorry for being "clueless"....everyone just thinks Im your avarage "blonde". LoL.

Thanks for your help again!
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Unread 07-25-2011, 07:22 PM   #6
02jeepAZ
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I'm sorry to bring the thread up again, but i'm currently am having the same problem of cylinder 3 misfire on my 02 jeep grand cherokee 4.7L , i drove the car for about 2 hours straight on saturday and parked the car that afternoon, when attempting to turn it on on sunday, the car only clicks when turning the key. i have read several threads and googled quite a bit, some say sparkplugs or coils can be the problem or even the injector, i'm currenty tight on money so my question is where is it best to start from as far as replacing and/or checking for problems on my car?
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Unread 07-26-2011, 12:28 AM   #7
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anybody???help would be greatly appreciated
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Unread 07-26-2011, 07:55 AM   #8
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Quote:
Originally Posted by 02jeepAZ View Post
I'm sorry to bring the thread up again, but i'm currently am having the same problem of cylinder 3 misfire on my 02 jeep grand cherokee 4.7L , i drove the car for about 2 hours straight on saturday and parked the car that afternoon, when attempting to turn it on on sunday, the car only clicks when turning the key. i have read several threads and googled quite a bit, some say sparkplugs or coils can be the problem or even the injector, i'm currenty tight on money so my question is where is it best to start from as far as replacing and/or checking for problems on my car?
move the coil pack to a different cylinder and see if the miss fire follows it. If it does you have a bad coil. If it does not move then try moving the injector to a different cylinder, if the code moves then it is a bad injector. You running the recommended plugs, I know the 4.7 is pretty sensitive to plugs.
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Unread 07-26-2011, 08:17 AM   #9
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Originally Posted by 02jeepAZ View Post
...when attempting to turn it on on sunday, the car only clicks when turning the key...
This line right here tells me it's something electrical or battery related. Does your vehicle start? If it literally just clicks when you turn the key over, I'd start by checking/charging your battery.
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Unread 07-27-2011, 07:18 PM   #10
02jeepAZ
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Wj

battery checked out fine when i took it to autozone, check starter relay fuse in the inside fuse box under the steering wheel and then checked outside fuse box in engine bay, checked all fuses and relays that i thought would be related to my problem, my next question is if the starter would be the problem, when turning the key and hearing the "click" sound is that my starter clicking? or does the click itself not make a difference and everything checking out fine would lead to possibly being the starter?
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