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Unread 04-15-2014, 08:01 PM   #1
ztyson89
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Replaced coil, plugs, and injectors; still throws a misfire code

First off, i have searched for similar issues and found none. I have a 2006 3.7L GC 65th, engine started "missing" a few times while at idle and around 1500-1700 rmp (light acceleration) so i changed plugs to Autolite double platinums. That seemed to fix the issue...for a day. Check engine light came on so i had the code read: p0303. Replaced the coil for cyl. 3 and switched the plug, coil, and injector from cyl. 3 to cyl. 1. Threw another code of p0301, so that narrowed it down to the injector. Replaced the injector today, drove it around for roughly an hour (performed fine; went through all types of accelerations, idle, cruise) Parked the Jeep for a few hours and when i got back in to drive it, the misfire was even more pronounced than before i changed the injector. had the code read: p0301 again. popped the hood and got a moderate smell of gas...Im puzzled guys! Any help is greatly appreciated

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Unread 04-15-2014, 08:09 PM   #2
tjkj2002
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1st you have the wrong plugs installed,copper core only.

Bad injector O-rings could be a cause of the smell since you should replace all the O-rings when you remove the fuel rail and re-install.A injector that is not fully seated also can be a issue.

For the misfire you can check the compression(on all 6 cylinders) to further help narrow down the cause.These engines can drop a valve seat if they overheat and it can take awhile to appear also.Granted it usually happens on cylinder #2 then any other cylinder.You can also check the coil and injector wiring back to the PCM.
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Unread 04-15-2014, 08:15 PM   #3
ztyson89
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1st: which plugs would you recommend?
And i thought new o-rings come with the new injectors? correct me if im wrong, im used to a distributor cap and spider.
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Unread 04-15-2014, 08:58 PM   #4
tjkj2002
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Quote:
Originally Posted by ztyson89 View Post
1st: which plugs would you recommend?
And i thought new o-rings come with the new injectors? correct me if im wrong, im used to a distributor cap and spider.
The stock plugs that are listed on the emission sticker under the hood,either NGK coppers or Champion coppers.

Yes a new injector will come with new O-rings but the other injectors on the rail will still have the old O-rings and the closest one to the replaced injector at least will break it's seal when you lift the fuel rail enough to remove the intended injector.
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Unread 04-15-2014, 09:32 PM   #5
ztyson89
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Thanks tjkj2002, I'm going to pick up some NGKs tomorrow and an o-ring pack. I bought the injector through advance auto parts, thinking that maybe that may be the issue possibly, it not being a mopar product. Any thoughts on that aspect of it? And thank you so much for your help so far.
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Unread 04-16-2014, 06:47 AM   #6
LouC
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I'm not sure on the 3.7 but with older Jeeps with the 4.0 & 5.2 changing the plugs from copper to platinum could cause misfires; the same is true of certain years of the 5.7 Hemi. I'd start with taking out the plat plugs and installing the coppers.
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Unread 04-16-2014, 08:56 AM   #7
ztyson89
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Yea LouC, that's what I was planning on doing. But wouldn't that cause all cylinders to misfire occasionally instead of just the one? It's just utterly confusing to me because if you read the first post, you can see how I narrowed the issue down and "fixed" the issue...but it's still occurring. And so you, LouC, have any input on the injector brand question I asked?
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Unread 04-16-2014, 09:04 AM   #8
LouC
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Even though you getting a misfire on just one for now I'd still change the plugs to start. Then see what it does. You are better off just changing one thing at a time when trying to trouble shoot a problem.

As far as the injector, it is very hard to generalize about aftermarket vs OE because there is such a wide variety in the quality of aftermarket parts. And sometimes (like with brake rotors on the ZJ/XJ/YJ/TJ) after market brake rotors are better than the crappy composite ones that were OE. I used to have a warping problem on my 98 ZJ every 11-15k miles that was cured 100% by going to Wagner full cast iron rotors that have lasted in excess of 75k miles. I usually will ask the counter guys in real auto parts stores (not the big chain stores) that sell more to independent mechanics about the quality of aftermarket parts.
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Unread 04-16-2014, 09:10 AM   #9
ztyson89
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Thanks LouC, think I'll go fiddlef**k with it for a few hours, see if I can get any results with new o-rings and NGKs. If anybody else reads this and has any time of input, please please please give it. The jeep is my fiancÚ' sand she is driving my truck until hers is fixed...I want my truck back
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Unread 04-17-2014, 11:22 AM   #10
ztyson89
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Well I have an update for y'all, I reseated the injector and replaced the o-rings. Also swapped my double platinum plugs for some cheap autolite copper core plugs. I moved the (new) coil pack from cyl 1 to cyl 3 and fired her up. I have been driving it since yesterday afternoon with no issues so far (knock on wood) thanks guys for all the help it means a lot to me knowing that there are people like y'all on this forum willing to help. Thanks!
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Unread 04-17-2014, 12:53 PM   #11
LouC
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Good for you...like I said, just do one thing at a time and then see what happens. I had a misfire problem like this on my wife's old Subaru. I looked at the ignition coil terminals and found one was rusted and the resistance readings were a bit out of range. So before doing a full tune up I replace the coil and drove it for 3 weeks. Was fine after that.
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Unread 04-17-2014, 01:25 PM   #12
ztyson89
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That's one thing that I checked also, the coil resistance. When I went to advance auto, the guys there told me that driving with the screwed up injector, it was causing the coil to fire "hotter" and that I probably screwed the coil, but when I checked the resistance, all the coils were reading with tight tolerance of each other. But that's neither here nor there, I'm rambling. Thanks again guys! Hope this fixes the issue and this thread will die.
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Unread 04-18-2014, 06:30 AM   #13
backliner
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i have the same issue (5.7 HEMI '08), first came alert from O2 sensors (first banks) i replaced it (the 4 sensors) and the alert came again, for 1 more day, after that alert gone and doesn't appear more. After that I replace 16 sparks, change oil and filters (air and oil) and now appears the alert again, but this time the scanner indicates an issue with injector 1 and 6, apply pressured air and after reset error codes, now appears issues with cylinders 1 and 2.... and a random misfire issues, when i drive i loss all power for a few miliseconds (with blinking alert), the some seconds after that the alert becomes static power restablished and then all is normal for a few minutes, then al the cycle again, blinking alert with loss of power, cylinders 1 & 2 doesn't function, then all normal... i think it can be dirty injectors, but...

brand representative doesn't want to see my WK, because it's aUS version, they want to "nationalize the car" (with previous payment of $1200... and a week to scan the car).

i saw few days ago about a COMBUSTION CHAMBER CLEANER... nobody in my country sell that, even... nobody knows about that product, even DIVEMOTORS (brand representative), they said: "that product is not used her, USA uses it, we don't"... somebody knows if that product can help?

I need to clean injectors? i begins to think that the system makes variations for some days to see if the system is OK, i really don't think so, but in some forums lots of people says that JEEP systems does that.... :/
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