Deleted Posted October 16, 2019 Author Share Posted October 16, 2019 4 hours ago, Money_Pits said: Random suggestion, but check the voltage output of your alternator under load. If the voltage regulator in it is going bad and supplying incorrect voltage, weird things can happen. voltage regulator is failing thats confirmed so maybe that is the cause of my issues, I'm just too broke to dish out 100$ on a new alternator right now Link to comment Share on other sites More sharing options...
Deleted Posted October 16, 2019 Author Share Posted October 16, 2019 1 hour ago, omega_rugal said: whoaa i knew mexican gasoline sucks but come one, it literaly ruined your MJ...... i don't know if the mexican gas is solely to blame as the two JKs I was with also drank from the same pond with no trouble but it definitely didnt help my engine in the moment lol Link to comment Share on other sites More sharing options...
Deleted Posted February 20, 2020 Author Share Posted February 20, 2020 I'm reviving this thread again because i'm somehow closer to figuring out the issue and still just as far away from fixing it. I have done everything I can think of, I got so fed up that it was still doing it after all these months that I finally caved and took it into the shop (Christian Brothers Automotive). They had my truck for 3 whole days and came back to me with the following report: "We have found that the computers in the truck think it is going 200mph when it is warm. We are trying to determine the source of the incorrect speed reading, this would cause the speed limiter to engage and cut out the power." After this all they basically did was unplug everything, clean it, plug it back in and see if that changed anything. They said they drove it for 40 miles without the problem popping back up and the speedometer needle no longer bounced around and was stably reading the speed so that night I picked up my truck. They werent confident it would be that easy so they didnt charge me yet and asked me to drive it around for a few days. The next day I drove about 70 miles (i work really far from home) with no issues but 5 miles from my house the issue popped back up. same as always, speedo needle jumping around, go over 2500rpms and lose power on and off. I called the shop back and took it in for another day. At the end of that day they called me and said its going to take some time since my ECU isnt original and the codes its throwing arent related to my vehicle since parts of the harness are missing due to the fact that my drivetrain was swapped with a 96 cherokee and with this issue they would need to keep the truck for about a week. Besides the labor costs that wasnt something I wanted to do so I said forget it and asked him what his recommendation on what to do was. He basically told me that the only way to go about fixing this is to 1.) replace the entire harness with something custom built for my frankensteined truck, and then 2.) start replacing parts until the problem goes away. So I guess thats where I'm at right now. Still have this issue, sorta know whats causing it, but in the end back to square one. On the bright side the shop didnt charge me since they didn't fix anything so that was nice. If anyone knows where I can get a custom harness for my 86 comanche with 96 grand cherokee parts I'm all ears lol. The shop recommended i email painless wiring which I did but still haven't heard back. I love my truck dearly but this issue really has me at my wits ends and makes me resent the previous owner for doing a swap half-a$$ed haha (and also myself for buying a swapped vehicle) Link to comment Share on other sites More sharing options...
eaglescout526 Posted February 20, 2020 Share Posted February 20, 2020 24 minutes ago, Pirate_Staz said: 96 grand cherokee Lets not touch a ZJ. I think it would be easier for you and I to get a damaged 96 XJ and harvest a good clean harness to start from scratch. Or there is that 89 Renix at AMC salvage we could do. Less problems Link to comment Share on other sites More sharing options...
OldManComanche Posted February 20, 2020 Share Posted February 20, 2020 You say that the speedo started bouncing again and your problem came back, maybe there is a link. Is the speedo cable driven or electric sender? You might try to unhook it and see if your problem goes away. You might also try driving in a lower gear at 2500 + RPM to see if the problem shows back up. This might tell you if it is a speed sensing problem (I doubt it), I would guess the ECU thinks the engine is over revving. 200 MPH REALLY?? I have a 1990 YJ Jeep. The original 4.2 I6 with carb had been replaced with a 97 HO I6. When I bought it it would barely run. Someone had done a half way installation, (kinda like your deal) of the Painless System. I cut it out and started over, (with the phone help of the guys at Painless). Now my Jeep runs like a fire truck on fire! But there was plenty of PAIN to get there! Link to comment Share on other sites More sharing options...
Deleted Posted February 21, 2020 Author Share Posted February 21, 2020 18 hours ago, OldManComanche said: Is the speedo cable driven or electric sender? You might try to unhook it and see if your problem goes away. You might also try driving in a lower gear at 2500 + RPM to see if the problem shows back up its electric, no cable. Ive consiered unhooking it but A) don't know how B) wasnt sure if itd mess with anything else. It does it in any gear which why I though it was a speed sensor. 18 hours ago, OldManComanche said: Someone had done a half way installation, (kinda like your deal) of the Painless System. I cut it out and started over, (with the phone help of the guys at Painless). Now my Jeep runs like a fire truck on fire! But there was plenty of PAIN to get there! This is probably what I need to do but I don't even know where to start/what harness to order/ or if I'm even capable of such a feat. Plus this is my daily for now so id need to do it all in one weekend Link to comment Share on other sites More sharing options...
Manche757 Posted February 22, 2020 Share Posted February 22, 2020 Someone solve this. Curiosity is killing me. Link to comment Share on other sites More sharing options...
eaglescout526 Posted February 22, 2020 Share Posted February 22, 2020 I’m thinking he just needs to do a whole new harness. Link to comment Share on other sites More sharing options...
JMO413 Posted February 22, 2020 Share Posted February 22, 2020 There is an input and output speed sensor in the transmission. There is also a speed sensor in the transfer case. The transfer case should run the speedometer. Link to comment Share on other sites More sharing options...
JMO413 Posted February 22, 2020 Share Posted February 22, 2020 After looking up these sensor I remember selling a ton of the output speed sensor in the early 2000's. They were popular enough we kept them in a drawer at the back counter. Link to comment Share on other sites More sharing options...
Manche757 Posted February 22, 2020 Share Posted February 22, 2020 4 hours ago, JMO413 said: There is an input and output speed sensor in the transmission. There is also a speed sensor in the transfer case. The transfer case should run the speedometer. If defective, would that cause the bucking or just the speedo to malfunction? Link to comment Share on other sites More sharing options...
OldManComanche Posted February 22, 2020 Share Posted February 22, 2020 (edited) Drive the truck till the problem shows up. Crawl underneath and unplug the speed sensor at the transfer case and try driving it. Does the problem go away? Good Luck! Edited February 22, 2020 by OldManComanche misspelling Link to comment Share on other sites More sharing options...
JMO413 Posted February 22, 2020 Share Posted February 22, 2020 8 hours ago, Manche757 said: If defective, would that cause the bucking or just the speedo to malfunction? I'm not real sure. If I was guessing I would think the output speed sensor would be the culprit. Link to comment Share on other sites More sharing options...
Deleted Posted February 25, 2020 Author Share Posted February 25, 2020 On 2/22/2020 at 8:44 AM, OldManComanche said: Drive the truck till the problem shows up. Crawl underneath and unplug the speed sensor at the transfer case and try driving it. Does the problem go away? Good Luck! Ill try this tomorrow after I get home from work and let you know. As for the diagram @JMO413 sent thats an AW4, I have the AX-15, will that matter too much or does that diagram still correlate to what I have? @eaglescout526 and I are going in about 2 weeks to the salvage yard where I plan on grabbing as much electrical as I can and just start rebuilding. Might even grab a spare ECU and see if its mine thats the problem. Link to comment Share on other sites More sharing options...
mjeff87 Posted February 26, 2020 Share Posted February 26, 2020 Just for grins and giggles, the next time the problem happens try unplugging the O2 sensor too and see if the problem goes away. My old MJ originally had a 2.5 that developed random, intermittent engine stumbles similar to yours that I spent weeks trying to figure out but never could. One day driving to work it acted up so I pulled over, popped the hood and started pulling sensor connectors. As soon as I disconnected the O2 sensor everything went straight back to normal. Replaced the sensor and never had another issue with it again. Its a no-cost test, worth a shot at least. Good luck Link to comment Share on other sites More sharing options...
JMO413 Posted February 26, 2020 Share Posted February 26, 2020 5 hours ago, Pirate_Staz said: Ill try this tomorrow after I get home from work and let you know. As for the diagram @JMO413 sent thats an AW4, I have the AX-15, will that matter too much or does that diagram still correlate to what I have? @eaglescout526 and I are going in about 2 weeks to the salvage yard where I plan on grabbing as much electrical as I can and just start rebuilding. Might even grab a spare ECU and see if its mine thats the problem. My mistake I some how thought you had an automatic. The only speed sensor yours has would be in the transfer case. Link to comment Share on other sites More sharing options...
eaglescout526 Posted February 26, 2020 Share Posted February 26, 2020 Well if he would get on he can tell us that he unplugged his speed sensor and his issue went away with the engine running rich. Link to comment Share on other sites More sharing options...
Deleted Posted February 26, 2020 Author Share Posted February 26, 2020 ALRIGHT YALL so a few things, my CEL does actually work and comes on when something isnt working as it should. How would I know this? Because I did what @OldManComanche said to do and I unplugged my speed sensor on the way home from work. Wouldnt ya know it the problem has dissapeared COMPLETELY. No stuttering, bogging, misfiring nothing nada zip. I can drive it in 5th gear at 3k rpms for extended periods, I can hit 4k in low gears (not that I normally do but I just wanted to let her breathe for once) and the problem seems to be all but cured. I had @eaglescout526 order me a new speed sensor and I'm gonna order a new gear and in a perfect world this will be the end of my issues. If for some reason plugging the new one in DOESNT work, I feel like now we finally know where to look. This has been a problem for a loooooong time now and I feel like its finally coming to a head Link to comment Share on other sites More sharing options...
OldManComanche Posted February 26, 2020 Share Posted February 26, 2020 Glad to hear it, but I would wait till after a few more drives to celebrate. If everything is good then enjoy it! Link to comment Share on other sites More sharing options...
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