mjbret13 Posted January 3, 2014 Share Posted January 3, 2014 88 comanche. Was running fine till a trail wheeling trip on New Year's Day. Lately it loves to high idle at 3000 rpm. There are no vacuum leaks or loose manifold bolts. Lately it would randomly idle at 3000 but shutting the jeep off and starting right back up had been solving the problem. Yesterday I replaced the IAC which gave me no problems during the test drive. After letting the jeep cool down I went to drive it, there it went back to 3000 rpm idle. The TPS was adjusted the day before per cruiser54's instructions. I have also done the ground refreshing. Link to comment Share on other sites More sharing options...
ftpiercecracker1 Posted January 4, 2014 Share Posted January 4, 2014 Stuck throttle cable? :dunno: Have you ever cleaned the Throttle body? Its would seem you have pretty much covered all the trouble areas, but then again i am not there to see it with my own eyes. You may be missing something obvious and we would never know it. Take some carb/choke cleaner and spray around all the vacuum ports and manifold to head mounting surface areas, if the engine sputters there is a vacuum leak in that area. Also, disconnect and cap your power brake booster vacuum line where it attaches to the manifold. That is a massive vacuum line and Intuition is telling me that if you booster was bad enough it could be the source of a pretty big vacuum leak. Link to comment Share on other sites More sharing options...
jeephack Posted January 4, 2014 Share Posted January 4, 2014 I have had a dash wire harness become dislodged and fall across the throttle cable keeping it from retracting completely. Probably not your problem but it only takes a few seconds to check. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 4, 2014 Share Posted January 4, 2014 I would start by clickng on the link in my signature and doing the ground refreshing, C101 cleaning, Connector refreshing and Sensor ground testing. The TPS adjustment procedure is in there also, but do the other groundwork first, in the order given. Good luck. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted January 4, 2014 Share Posted January 4, 2014 He. already did that Link to comment Share on other sites More sharing options...
cruiser54 Posted January 4, 2014 Share Posted January 4, 2014 I only see ground refreshing and TPS adjustment in post #1. Link to comment Share on other sites More sharing options...
mvusse Posted January 4, 2014 Share Posted January 4, 2014 I sporadically had the same issue, but it became more and more prevalent. In my case the issue was the throttle position sensor. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 4, 2014 Share Posted January 4, 2014 I sporadically had the same issue, but it became more and more prevalent. In my case the issue was the throttle position sensor. Yep. Leaning that direction myself. but now would be a good time to check the sensor ground circuit as it not only affects the TPS, but the CTS, IAT and MAP. Their signals run through the C101 also. Link to comment Share on other sites More sharing options...
mjbret13 Posted January 4, 2014 Author Share Posted January 4, 2014 Seemed to fix the problem for now but I still have a high ohm reading between ground at the battery and the TPS sensor. I have cleaned the c101 connector the best I could do in the cold and dark last night. Reading went from 12 to 10 ohms of resistance but I want to make it as low as possible. I think I'm going to give my self a project and lable all the injectors and remove the engine side of the harness and clean all the grounds to get it lower. Even possibly install a grounding jumper to bypass the c101 to see if that helps. Is there any good write ups to remove the c101 or should I just pull the harness off a 89 or 90 xj or mj? Link to comment Share on other sites More sharing options...
cruiser54 Posted January 4, 2014 Share Posted January 4, 2014 I have a writeup in that link for Sensor Ground Upgrade........ Link to comment Share on other sites More sharing options...
mjbret13 Posted January 11, 2014 Author Share Posted January 11, 2014 Since discovering my problem is caused by the c101 connector I have since then cleaned the hell out of it and it's been running fine since. I am on the look out for the engine wiring harness out of a 89.5-90 xj or mj just so I can eliminate the c101. Also clear up that spot on the firewall. Plus my harness has hardly any of its wires bundled together like they should anymore. I do admit installing the wiring cover off an H.O has cleaned up the wiring a lot. Link to comment Share on other sites More sharing options...
mvusse Posted January 11, 2014 Share Posted January 11, 2014 I sporadically had the same issue, but it became more and more prevalent. In my case the issue was the throttle position sensor. Even though the TPS was bad, I just had it happen again yesterday, with the new TPS. So evidently the cause was NOT the TPS. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 11, 2014 Share Posted January 11, 2014 Since discovering my problem is caused by the c101 connector I have since then cleaned the hell out of it and it's been running fine since. I am on the look out for the engine wiring harness out of a 89.5-90 xj or mj just so I can eliminate the c101. Also clear up that spot on the firewall. Plus my harness has hardly any of its wires bundled together like they should anymore. I do admit installing the wiring cover off an H.O has cleaned up the wiring a lot. You can eliminate the C101 by soldering the wires together. I have a link somewhere. That said, I've found that most times cleaning the c101 thoroughly as you have done, fixes it forever. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 11, 2014 Share Posted January 11, 2014 I sporadically had the same issue, but it became more and more prevalent. In my case the issue was the throttle position sensor. Even though the TPS was bad, I just had it happen again yesterday, with the new TPS. So evidently the cause was NOT the TPS. How's YOUR C101? Sensor ground test results? Link to comment Share on other sites More sharing options...
mjbret13 Posted January 11, 2014 Author Share Posted January 11, 2014 I'm just going to get another harness and redo all of the factory grounds within the engine management harness. That should solve all of the grounding problems that reek havoc with engine problems. Link to comment Share on other sites More sharing options...
mvusse Posted January 12, 2014 Share Posted January 12, 2014 I sporadically had the same issue, but it became more and more prevalent. In my case the issue was the throttle position sensor. Even though the TPS was bad, I just had it happen again yesterday, with the new TPS. So evidently the cause was NOT the TPS. How's YOUR C101? Sensor ground test results? Your thinking the same thing I am. Link to comment Share on other sites More sharing options...
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