$1,000+ in, Multiple cylinder misfire still fighting back!

WHITE the civilian · **Posted:** Sun Mar 02, 2014 2:51 am

My 2006 KJ limited has served me well for the time I've owned it.
Despite a few cross country trips (NY to AK) at about 80K miles on her now.

Check engine light came on and the code for multiple cylinder misfire has been destroying me financially. Over a thousand Washingtons have been sent away and the jeep comes back all willy nilly like nothing was changed.

All Spark plugs have been changed twice over the course of a few months most recently the plugs that originally came in the jeep were put in. All o2 sensors have been replaced as well.

What else can cause my blinking check engine light to exist?
If this can't be fixed I'm trading her in and settling for another poopy vehicle.

HoosierJeeper · **Joined:** Sun Feb 15, 2009 8:23 am **Posts:** 1218

Something with the coil packs maybe?

streetglideok · **Posted:** Sun Mar 02, 2014 12:43 pm

First thing is what cylinders have misfires on them? Has a compression test been performed on those cylinders? If you have good compression, then look at injectors. Before I would start throwing money hand over fist at replacing them, swap their locations with cylinders without misfires. Has this work been done at a regular shop or at home?

WHITE the civilian · **Posted:** Mon Mar 03, 2014 1:14 am

ALL cylinders are experiencing a misfire, compression is good and a trusted local shop saw nothing out of the ordinary when they went in and changed spark plugs and o2 sensors.

03CDKJ · **Posted:** Mon Mar 03, 2014 2:25 am

$1000 in 2 sets of spark plugs and 4 02 sensors.... You got hosed!

disconnect the battery.....take out the coil packs.... take out the spark plugs.... get copper ones if you don't all ready have them... RE CHECK THE GAP.... Check the coil packs out and make sure they have a spring in them..... make sure they are CLEAN AND DRY.... if not... clean and dry them.... Put some DIELECTRIC GREASE on the coil pack connection where they plug into the harness.... Put in clean PROPER GAPPED PLUGS... put in coil packs. Make sure they are connected.... Reconnect Battery and report back....

If they are all still bad....
Replace coil packs.... and report back....

Thats all we can do from the net... :JEEPIN:

streetglideok · **Posted:** Mon Mar 03, 2014 10:42 pm

Yeah it's going to be difficult to pin this down online. Need to watch the datastream while it's running. See how the fuel trims are responding, etc. Did they use non-bosch O2 sensors? If they used bosch garbage, that alone can and will cause issues. May pay to verify it has not jumped time.

tjkj2002 · **Posted:** Mon Mar 03, 2014 10:49 pm

Need to check the battery,compression,fuel pressure,grounds,but 1st I'd be checking the cats.I've run into some misfire issues with 3.7/4.7'ss and bad cats without cat codes.

infernicus · **Posted:** Tue Mar 04, 2014 7:21 pm

streetglideok wrote:

....Did they use non-bosch O2 sensors? If they used bosch garbage, that alone can and will cause issues....

Not to thread jack.. But how accurate is this statement? Are Bosch O2 Sensors that bad?

tjkj2002 · **Posted:** Tue Mar 04, 2014 7:24 pm

infernicus wrote:

streetglideok wrote:

....Did they use non-bosch O2 sensors? If they used bosch garbage, that alone can and will cause issues....

Not to thread jack.. But how accurate is this statement? Are Bosch O2 Sensors that bad?

Yes they are that bad in Chrysler engines as they do not switch fast enough for our PCM's liking.

infernicus · **Posted:** Tue Mar 04, 2014 7:28 pm

(Sorry WHITE)
Booo, I know there was a reason I put OEM last time.

What will I see/expect with a Bosch in there?
(With the deep snow I keep messing up the wire for the sensor and it keeps tearing. Do they need a specific resistance or length of wire? Or can I just splice the wire back together?

The_dealer · **Joined:** Wed Jan 08, 2014 8:41 pm **Posts:** 129

There's nothing you can do besides replace them with NTK, which is what the oem are. Bosch and mopar don't play very well as stated. Securing the wires where it won't keep getting snatched will be a good place to start.

OP, I also agree with tjkj2002. I'd check the cats out, which alot of the time is the culprit of a multiple misfire. You mentioned a blinking cel, but didn't say what codes? It sounds exactly like the problem my aunt had with her wj when the cats took a dump. Are u getting a misfire on the first xx revolutions code?

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WHITE the civilian · **Posted:** Sun Mar 16, 2014 2:57 am

P0300 <<<< multiple cylinder misfire?

P015 <<< Deleted the other portion of this one. I had a severe electrical draw, example being you're driving at night (headlights on) you open or close the windows and the headlights dim REALLY BAD!

Jeepjeepster · **Posted:** Sun Mar 16, 2014 4:36 pm

My head lights dont dim when i open the doors or use my power windows??

Have you seriously spent $1,000 on spark plugs and O2 sensors?

The_dealer · **Joined:** Wed Jan 08, 2014 8:41 pm **Posts:** 129

Have you had your battery and alternator tested?

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streetglideok · **Posted:** Mon Mar 17, 2014 10:26 pm

WHITE the civilian wrote:

P0300 <<<< multiple cylinder misfire?

P015 <<< Deleted the other portion of this one. I had a severe electrical draw, example being you're driving at night (headlights on) you open or close the windows and the headlights dim REALLY BAD!

Hmm. When did this all start happening? What was done to the vehicle before this happened? With the lights dimming, a missing or disconnected ground wire comes to mind. That can cause running issues, etc.

The_dealer · **Joined:** Wed Jan 08, 2014 8:41 pm **Posts:** 129

I went through a host of electrical problems, which all came from a crap trailer wiring job.
1)Check all of your grounds, check the straps and sand/clean them good where they mount to the firewall and fender.
2) Check the wire going from the alt to the dist. Block, and check them for continuity. There's fusible links that could be burned out. Wiggle them around while it's running and see what happens.
3) Run a ground wire from the pcm case to either the ground on the fender, or a self tapper.

I'd also get one of those cheap volt meters that go in your lighter socket and watch the voltage while driving. I've heard of slight light dimming while rolling a window up or down, but it should be barely noticable. You can check your grounds with a multimeter against a good known ground (battery). What's your voltage at the battery with the jeep off, and at idle?

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WHITE the civilian · **Posted:** Fri Mar 21, 2014 8:11 pm

It happened a few months after I arrived in Anchorage, AK after driving from N.Y 6,000+ mile trip. Regular maintenance has been done and I just purchased a Sears Platinum one battery which helped with starting a lot when it dipped below 0*F. Its most likely the alternator, it's been on there since "06". I spent over $900 in sensors and getting spark plugs replaced within a few months of each other trying to diagnose the issue at a reputable shop a Chrysler dealership first then a local shop with people lined up for miles down the road ranting and raving about how good they were.

Lambeau · **Joined:** Fri Jul 06, 2012 12:17 pm **Posts:** 23

First off, I am not a Mechanic in a Can guy. After a couple random P0304/P0306 codes on our 2006 KJ, I did some research with fellow car guys. I ended up dumping in a bottle of this in the tank (~$10). Make sure it is Techron.

The KJ has been driven +3,000 miles with no additional codes. I attribute the codes from dirty injectors. Hope this helps!!!

WHITE the civilian · **Posted:** Tue Mar 25, 2014 1:48 am

Lambeau wrote:

First off, I am not a Mechanic in a Can guy. After a couple random P0304/P0306 codes on our 2006 KJ, I did some research with fellow car guys. I ended up dumping in a bottle of this in the tank (~$10). Make sure it is Techron.

The KJ has been driven +3,000 miles with no additional codes. I attribute the codes from dirty injectors. Hope this helps!!!

Am entire bottle into the tank? Wonder if local stores have it. I'll do that tomorrow.

Edit: local Oreilly's has it. I'll let you know, getting my first tank of premium tomorrow as well.

WHITE the civilian · **Posted:** Tue Mar 25, 2014 8:56 pm

I went to O'Reilly auto parts bought the Techron (buy 1 get 1 :-)r

) proceeded to the gas station - arrived and dumped the Techron in the rest was premium and drove 5-10 miles around town. CEL is still on as of now.

$1,000+ in, Multiple cylinder misfire still fighting back!

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