I have an 06 LJ auto with 139900 miles on it. CEL has been on since I got it for a o2 sensor heater circuit. I used a multimeter to test the circuit and all values were within spec. I replaced the o2 sensor with an oem one. After every attempt i’ve reset the light and it keeps coming back on. A little bit ago I put like 4 gallons of 88 gas in my my jeep and it was causing a misfire. Putting 87 back in fixed that...or so I thought. It’s been about 2-3 full tank fill ups since the 88 was in there but all of a sudden today my jeep is misfiring again. It only happens under acceleration at a certain rpm when the transmission in shifting. I will cut the jeep off and back on and it’ll go away until I accelerate again. When i had the 88 in there the misfire would rarely happen but now the misfire happens every 200 feet. I pulled over every time it happened and cut the jeep off and back on. I was thinking it had to do with the o2 sensor but I disconnected the battery and the misfire still happened. I haven’t checked the code yet to see which cylinder it is or if it’s multiple random misfires. Any ideas? Is it a bad PCM?
Could my PCM be bad?
- Thread starter Chasitek
- Start date
There is a service bulletin out to fix this issue.
Read this thread.
https://wranglertjforum.com/threads/sb-25-001-07.1703/
I did it to my 06 TJ a month or so ago and it solved the problem.
Read this thread.
https://wranglertjforum.com/threads/sb-25-001-07.1703/
I did it to my 06 TJ a month or so ago and it solved the problem.
Southtowns27
Member
I wasn’t sure. I just know my jeep started misfiring after putting that in. That’s it.
Thanks so much man. I will do this first thing.
Do you guys think the o2 heater sensor circuit is also what’s causing the misfire? I’m thinking it’s starving the engine of fuel?
edit: getting a p2305 code. Gonna replace coil pack rail
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It sounds pcm related to me. The bad o2 sensor codes are a tell-take sign of a bad pcm. The acceleration issues with the transmission could also be pcm related...any other codes that have came up? Hard shifts?
Well I occasionally have the hard shift from 1st to 2nd but haven’t had it in a while. I pulled my spark plugs and checked the gaps and all gaps were wayyy too big so I regapped them and reinstalled them. I’m gonna get some new ones but just didn’t have another vehicle to run to the store. I have a P2305 which is for ignition coil “B” secondary circuit and a P0161 for the o2 sensor. The misfiring all of a sudden went away yesterday. I gapped the spark plugs and reset the CEL and about a mile down the road it was misfiring AGAIN (seemed to be when it got up to operating temp) so I stopped at advance to read the codes since it was 100 ft down the road. The same 2 codes came back and I left advance and the misfire went away. They didn’t reset the CEL or anything so now i’m just stumped. The TSB for the o2 sensor says the diagnosis is tO turn the key to the on position and that after 10 seconds the MIL(CEL) will flash 15 times and then turn solid. Mine does in fact do that so I was going to try the fix for the o2 sensor and see if that fixed any problems. How would I go about diagnosing a bad pcm?
Once the hard shift comes, it’s the beginning of the end for the pcm. It can go away for awhile without occurring but it’s 100% pcm related.
Noted. Thanks. So i’ve read about tons of people who have fixed it and haven’t fixed it by getting a new OEM pcm. I don’t think i’m going to get a new one as i’ve read it’s just the programming. If I flash the PCM would that fix it? Or if I buy the pcm from wranglerfix. com? What’s the most documented fix?
There are no new oem pcms available and anyone claiming to fix these pcms is selling you a pig in a poke.
The processors aren’t available and it’s like trying to put Humpty Dumpty back together. Digging the gel out alone is an hour of tech time.
Here is a video that I made about our pcm vs. oem a couple of months ago.
As far as reliability...Our solution works and we stand behind it. Here’s a video testimonial from a customer.
You can call me if you’d like. 866-888-7710.
Thanks,
Mark
I have an 03 TJR that hard shifts when it’s cold from 1st to 2nd. I’ve heard the 05-06 Pcms go bad but not so much on an 03. Is this a sign of a bad pcm in my 03 or just how an old (cold) transmission shifts with 106,000 miles?
I can’t speak for the first 95,000 miles, previous owner who I bought it from said the tranny fluid was just changed at 95,000. It looks clean and red and proper level.
There is a software update for a harsh down shift, and you may want to have that done first. If the problem still exists it could be a valve body problem in the trans or sensor that is acting up. I would get it flashed first and have the dealer do a "relearn" procedure with their scan tool. Hopefully this will take care of your problem. Let me know what happens.
Thanks,
Mark
Before replacing anything else, check your wiring harness for chafing. You want to look at the large loom that runs down the passenger side of the engine block near the fire wall. The wiring for the coil pack, 2/2 02 sensor and PCM grounds all run through this loom. Note also that this loom needs to rest on the coil pack. If it's between the coil pack and the block, it's rubbing on the block and it will wear through. That you're experiencing issues when the transmission shifts also points to a wiring harness shorting on the block as the engine mounts flex.
Also: 25-001-07 will not resolve P0161. This TSB addressed an emissions testing communication error. The light could also be blinking (KOEO) because the battery was disconnected. With the '05-'06 TJ, the PCM requires 3 drive cycles to reset the flashing MIL even if the TSB has been performed.
Also: 25-001-07 will not resolve P0161. This TSB addressed an emissions testing communication error. The light could also be blinking (KOEO) because the battery was disconnected. With the '05-'06 TJ, the PCM requires 3 drive cycles to reset the flashing MIL even if the TSB has been performed.
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I haven’t even tried the TSB yet. My jeep has been parked for the past week. I’m waiting on a new radiator to arrive. Do you have a picture of the harness?
Paranoid057
New Member
Have also seen issues from the harness rubbing through when resting on the AC dryer causing all sorts of havoc