Misfire on 07 stock 3.8
11-20-2017, 12:12 AM
#21
JK Freak
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Without proper crankshaft reading the PCM can have trouble timing the TDC and igniting the mixture. So then you end up with misfires. Obviously changing anything but addressing the issue with crankshaft signal will give you zero results.
11-20-2017, 03:32 AM
#22
JK Jedi Master
Yes, that is one item on the long list of items that can cause the crank to slow.
Last edited by ronjenx; 11-20-2017 at 03:53 AM.
11-20-2017, 04:35 AM
#23
JK Enthusiast
Misfire under load is usually a Bad sparkplug or plug wire. I suggest changing all the spark plugs and don't try and go fancy. The 3.8 likes the factory Champion platinum plugs. Anything else will likely cause you more grief... If factor original plug wires are still on there, change them as well.
I found the problem. Poor connection on the #6 wire at the distributor. I don't know why yet, as I resolved the issue on the way to work. Ill check later to see if corrosion or moisture. (all plugs, wires, distributor replaced 25000 miles ago at 130,000)
Thanks to all for the advice.
11-20-2017, 05:23 PM
#24
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I found the problem. Poor connection on the #6 wire at the distributor. I don't know why yet, as I resolved the issue on the way to work. Ill check later to see if corrosion or moisture. (all plugs, wires, distributor replaced 25000 miles ago at 130,000)
Thanks to all for the advice.
Thanks to all for the advice.
12-30-2017, 02:37 PM
#25
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Shaking engine to almost a stall when stopped in gear. 2007 JK. DTC misfire on cylinder #2. Checked with spark plug out of cylinder and in sight to watch for spark. Sure enough, no spark. Tried that wire and plug on another channel and it was working (therefore confirmed bad coil pack). Replaced for $50 . Fixed.
03-18-2019, 10:14 PM
#26
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Shaking engine to almost a stall when stopped in gear. 2007 JK. DTC misfire on cylinder #2. Checked with spark plug out of cylinder and in sight to watch for spark. Sure enough, no spark. Tried that wire and plug on another channel and it was working (therefore confirmed bad coil pack). Replaced for $50 . Fixed.
09-09-2019, 01:14 PM
#27
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My 2007 Rubicon is doing the same thing.
Ronjenx I see you posted this check list many times on this site. Do you have insight into this problem. I'm tr ing to avoid tare down of my engine for a stumble at idle with a ce light. I could see the test procedure would prove vital for a random missfire.
But mine is isolated to #2 with all basic parameters in spec. This is a out of the ordinary issue. And that's why I'm asking for help. Trying to avoid hours of diagnosis.
But mine is isolated to #2 with all basic parameters in spec. This is a out of the ordinary issue. And that's why I'm asking for help. Trying to avoid hours of diagnosis.
My 2007 Rubicon is doing the same thing except mine is not firing out of the bottom 2 of the coil pack ,no fire at all . I’ve been trying to figure it out over a month now.
so far I’ve replaced the pcm,the coil pack 3 times plugs and wires the crank and cam positioning sensors and replaced the wires between the pcm and the coil pack still no fire on the bottom 2 prongs at the coil pack ,
you might check to be sure the prong directly across from the one that’s not firing and make sure it’s firing . Because the coil pack is actually 3 coils inside of the pack one coil runs 2 cylinders and the plug is 4 wires 3 coming from the pcm that control the coil and the brown /white one comes from the auto shutdown relay its the 5v trigger wire . I guess I’m going to have to take mine somewhere I can’t figure it out and nothing on these forums can tell me what is causing the bottom of the coil pack not to work .
09-10-2019, 06:33 PM
#28
Just something to do a visual on. On my '09 The wire conduit Jeep used is crumbling. I've replaced as much as I can get to, but it's possible the stuff has fallen off and you have a wire to the coil pack that's shorting.
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hornetman (11-04-2019)
11-04-2019, 03:23 PM
#29
JK Enthusiast
For Coil Pack, plugs and wires do you recommend OEM or something else? Just popped a P303 this morning on my way to work, music was cranking and I felt hesitation and louder noise from exhaust. 92K and last time I changed the plugs was about 40K miles ago. Still have stock wires and coil pack. I did replace wire lume about a month ago because of mostly crumbling heat/age deteriorating. Had my Jeep towed to house as I had the CEL & red lightening bolt and didn’t want to risk unknown damage. So going to add all new plugs, plug wires, & coil pack just need to know if I should get from local dealership.
11-05-2019, 04:02 AM
#30
For Coil Pack, plugs and wires do you recommend OEM or something else? Just popped a P303 this morning on my way to work, music was cranking and I felt hesitation and louder noise from exhaust. 92K and last time I changed the plugs was about 40K miles ago. Still have stock wires and coil pack. I did replace wire lume about a month ago because of mostly crumbling heat/age deteriorating. Had my Jeep towed to house as I had the CEL & red lightening bolt and didn’t want to risk unknown damage. So going to add all new plugs, plug wires, & coil pack just need to know if I should get from local dealership.
FWIW, the red lightning bolt suggests you have an issue with the electronic throttle., throttle body, etc. The harness connector at the throttle body is a POS and may have crumbled or popped off. You can get a new one with a splice kit, but pricey. Mine broke when I tried to reinstall it. Was able to source the connector and install it on the existing harness.
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hornetman (11-05-2019)