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Unread 10-04-2013, 10:55 AM   #16
prjohnson
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Quote:
Originally Posted by goodwrenchdave View Post
Do you have a warranty as you just bought it?

sounds almost like it was sold because of this problem.

reading material.... not saying it's this as it has to be diagnosed but:

http://www.wjjeeps.com/tsb/tsb_wj_0900303.pdf
remember this can get expensive fast!

A very simple check is to just decarbonize first and check results.
I wonder if you could use that cleaner to prevent this from happening.

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Unread 10-04-2013, 11:16 AM   #17
SpecialTwinky
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Also it usually happens around 40 mph and up. And how would I check exhaust back pressure
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Unread 10-04-2013, 12:14 PM   #18
aTX427
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Originally Posted by SpecialTwinky View Post
I just put brand new Bosch Double Platinum plugs. The codes were p0300 301 303 304 305 306. What are mopar wires and how do I change them? And it is an automatic
I forgot the newer models don't use pug wires. I would still check all your engine ground wires and ditch those plugs in favor of some cheap Champion copper plugs. If that doesn't help try the CPS. These engines are very reliable, but only seem to like Mopar brand electrical components and copper plugs.
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Unread 10-04-2013, 01:51 PM   #19
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These engines are very reliable, but only seem to like Mopar brand electrical components and copper plugs.
My 2000 Sport runs very well with Champion 7034 spark plugs...
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Unread 10-04-2013, 05:22 PM   #20
SpecialTwinky
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I will be checking the CPS tonight or tomorrow and report to tell you guys if it worked.
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Unread 10-04-2013, 06:38 PM   #21
TJJP77
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I'd pull those Bosch plugs out of there. There's been several reports of 4.0L's not playing nice with them. If your problem started after installing the plugs, then there's your answer.
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Unread 10-04-2013, 06:41 PM   #22
SpecialTwinky
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Quote:
Originally Posted by TJJP77 View Post
I'd pull those Bosch plugs out of there. There's been several reports of 4.0L's not playing nice with them. If your problem started after installing the plugs, then there's your answer.
I put those in after to try and fix the problem
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Unread 10-04-2013, 06:45 PM   #23
SpecialTwinky
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Can somebody give me a list of things to check first? Mostly things that I should be able to do without needing a lot of experience with wiring.

Last edited by SpecialTwinky; 10-04-2013 at 07:05 PM..
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Unread 10-04-2013, 07:32 PM   #24
SpecialTwinky
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My dad just told me that somebody that he worked with said that it could be misfiring because it is running too rich. Could that be a legit reason? It does smell like it is running very rich. Also I pulled the new plugs out and they are very black. I have only drove it once or twice after changing the plugs and they are already black.
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Unread 10-04-2013, 07:34 PM   #25
goodwrenchdave
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Unfortunately, without any "tools", there isn't much you can check. By tools
I mean scanners, gauges etc. do you hear any valvetrain noise, tapping/ticking? (not injector tick),
Do you feel it at a certain RPM more or at a particular speed more? Does the CEL flash or it just lights solid.
have a quick look at the crank sensor with a flashlight - does it look new?
Do any sensors/parts on the motor look new?
You changed the spark plugs (and to not a preferred brand by many) and that's probably about all you can visually do). What did they look like? Was there any carbon tracking on the ceramics/coil assy? (thin dusty black lines- spots)
You know you have a misfire but there are many things that can cause it.
some simple as a sensor or learn calibration to bad gas to mechanical issues such as the bulletin explains. Just for sh!ts and giggles you can add some injector cleaner in the tank, if you don't feel like spraying combustion chamber cleaner in the intake. Don't baby it either (a few WOT's on open roads to raise the rpm's so the engine "expels the mucuus").
Would't wait too long to get it fixed either as raw fuel is very bad for catalytics...plugs them up.

Do you know if any repairs done recently (by other owner)?
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Unread 10-04-2013, 07:45 PM   #26
goodwrenchdave
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Quote:
Originally Posted by SpecialTwinky View Post
My dad just told me that somebody that he worked with said that it could be misfiring because it is running too rich. Could that be a legit reason? It does smell like it is running very rich. Also I pulled the new plugs out and they are very black. I have only drove it once or twice after changing the plugs and they are already black.
oh??
so your running real rich
You may have a bad upstream 02 sensor (out of calibration).- strange it didn't code a system lean/rich... but sometimes it doesn't.
Also look at the vacuum line going to your map sensor . check for dry splitting, cracks/vacuum leaks.

unplug the upstream o2 (make sure the connectors don't touch any hot exhaust). REM: It will set an o2 code. Run under the same conditions for the misfires and see if it went away.... The ECM will use it's "basic" fuel mapping based on temperature, load and displacement, and not try to adjust from O2 readings,
Did your mechanic see any value a little off in the data parameters? Fuel trim learn?
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Unread 10-04-2013, 09:09 PM   #27
SpecialTwinky
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Two more extra pieces of info: just got the codes pulled and now they are p0301 302 303 304 306. It's every cylinder but five and this is after I changed the plugs. The old plugs were every cylinder but 2 and 5. The second thing is that it idles very rough right after I turn on my jeep, I let it go for a few minutes and nothing changed. I then drove it around and it didn't idle like that after twenty minutes if driving and it was fine. Does this help pinpoint something? (Autozone said that it could be something with my timing belt).s

No p0300 code.

Last edited by SpecialTwinky; 10-04-2013 at 09:38 PM..
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Unread 10-04-2013, 09:22 PM   #28
SpecialTwinky
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Quote:
Originally Posted by goodwrenchdave View Post
Unfortunately, without any "tools", there isn't much you can check. By tools
I mean scanners, gauges etc. do you hear any valvetrain noise, tapping/ticking? (not injector tick),
Do you feel it at a certain RPM more or at a particular speed more? Does the CEL flash or it just lights solid.
have a quick look at the crank sensor with a flashlight - does it look new?
Do any sensors/parts on the motor look new?
You changed the spark plugs (and to not a preferred brand by many) and that's probably about all you can visually do). What did they look like? Was there any carbon tracking on the ceramics/coil assy? (thin dusty black lines- spots)
You know you have a misfire but there are many things that can cause it.
some simple as a sensor or learn calibration to bad gas to mechanical issues such as the bulletin explains. Just for sh!ts and giggles you can add some injector cleaner in the tank, if you don't feel like spraying combustion chamber cleaner in the intake. Don't baby it either (a few WOT's on open roads to raise the rpm's so the engine "expels the mucuus").
Would't wait too long to get it fixed either as raw fuel is very bad for catalytics...plugs them up.

Do you know if any repairs done recently (by other owner)?
The cel flashes when it happens and it happens more at 45+. It only happens once and I have to pull over, turn it off and then it doesn't happen anymore for that drive. And by carbon tracking do you mean the black stuff that gets on the bottom of the spark plug that is supposed to be white? Here is a picture of an old spark plug that was used before I changed them.

For any of the sensors and stuff looking new, I haven't checked or even paid attention to if they are new or not. How do I tell? The motor and sensors under the hood are very clean.

No repairs that I am aware of at this moment.

Last edited by SpecialTwinky; 10-04-2013 at 09:37 PM..
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Unread 10-04-2013, 09:28 PM   #29
SpecialTwinky
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Sorry I can't upload the pictures but the bottoms are very black and I know they aren't supposed to be.
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Unread 10-04-2013, 10:19 PM   #30
TJJP77
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Quote:
Originally Posted by SpecialTwinky View Post
I put those in after to try and fix the problem
What plugs were in it before the Bosch plugs?

I still say pull the Bosch plugs and put some Champion or NGK plugs in it. Both were OEM specified at one point in time or another on the coil rail engines, so you know they work. Sometimes these coil-on-plug systems are sensitive to resistance/feedback in the plug circuit and that feedback shuts down the coil drivers in the PCM to protect it from damage. As an example, Hemi engines are notoriously sensitive to the brand of plugs that will work with them - Bosch platinum plugs will make a Hemi stall, yet Champion platinum plugs will not.
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