last254 Posted December 10, 2012 Share Posted December 10, 2012 so i have an 87 manche 4.0 4wd with nv3550 that has been fairly reliable but has a high idle problem. when i first start it up it is good at only 1000 rpm but as it warms up the idle will drop down to 400-500 a few times until its finished warming up then it remains at 1000 constant. However once i begin to drive the idle at a stoplight is typically around 1600 way too high. Also i don't know if its related but it will occassionally stall on me but I have made no relations as to what happens the stalling seems to be a very random and intermittent problem. Any thoughts on what should be tested or what direction to move in first? Link to comment Share on other sites More sharing options...
ComancheKid45 Posted December 10, 2012 Share Posted December 10, 2012 Could be 1 or many things. Start simple... Check Manfold bolts for looseness Clean TB and IAC check TPS voltage check all vacuum lines and hoses. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 11, 2012 Share Posted December 11, 2012 Good advice^^ here. I'm betting your TPS is taking a dive. Read my write-up on TPS adjustment in the link in my signature. Pay particular attention to the sensor ground test. BTW, have you ever refreshed the grounds or cleaned the C101 connector on your Jeep? Link to comment Share on other sites More sharing options...
last254 Posted December 11, 2012 Author Share Posted December 11, 2012 i am very familiar with cruiser54's electrical write ups and will begin going through every single one once school ends this thursday. I bought this jeep so i could learn about cars and i've come a long ways imo but love working on my jeep. comancheclub is definitely the best forum site ever and i just wanna kinda get a list together of what to check cuz i'll have lots of time after this thursday Link to comment Share on other sites More sharing options...
cruiser54 Posted December 11, 2012 Share Posted December 11, 2012 i am very familiar with cruiser54's electrical write ups and will begin going through every single one once school ends this thursday. I bought this jeep so i could learn about cars and i've come a long ways imo but love working on my jeep. comancheclub is definitely the best forum site ever and i just wanna kinda get a list together of what to check cuz i'll have lots of time after this thursday Do what ComancheKid45 suggested also. Link to comment Share on other sites More sharing options...
last254 Posted December 12, 2012 Author Share Posted December 12, 2012 will check manifold bolts tomorrow as wells as tps voltage but i only had a lil time today so i cleaned the tb iac and the c101 connector. if i have time i plan on updating all my grounds as well. cruiser's write up's just seem like the most necessary tune up these 25 year old trucks need. also any ideas on the random stalling every once in a while? do you think it may be related to the high idle? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 12, 2012 Share Posted December 12, 2012 will check manifold bolts tomorrow as wells as tps voltage but i only had a lil time today so i cleaned the tb iac and the c101 connector. if i have time i plan on updating all my grounds as well. cruiser's write up's just seem like the most necessary tune up these 25 year old trucks need. also any ideas on the random stalling every once in a while? do you think it may be related to the high idle? Take care of the basics like ground refreshing, manifold bolts, connector refreshing first. They all need it. If the stalling persists after that, I would test the CPS. Come to think of it, has it stalled randomly since the c101 cleaning? Link to comment Share on other sites More sharing options...
last254 Posted December 12, 2012 Author Share Posted December 12, 2012 ill do that list and well the stalling is more of like a once a week thing so it is hard to tell but the idle problem still persists although that c101 really needed it wow your right about that nasty gunk getting hard. i have a question though what do you mean by connector refreshing like all my sensor connectors or just the relay panel on the passenger fender? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 12, 2012 Share Posted December 12, 2012 I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight. ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else. Revised 07/23/2012 Link to comment Share on other sites More sharing options...
last254 Posted December 12, 2012 Author Share Posted December 12, 2012 hey cruiser i went to check the ground on my dispstick stud and they are all idk how to describe it but behind the bolt how can i take that bolt out and properly clean the area, do you think the PO might have done that area already. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 12, 2012 Share Posted December 12, 2012 It's usually a stud with a nut, but could be a bolt if someone changed it. I would definitely remove and clean everything up. Link to comment Share on other sites More sharing options...
last254 Posted December 14, 2012 Author Share Posted December 14, 2012 so i think its a stud with a washer looking thing in front of the oil dipstick tube bracket and the ground wires behind the so called washer but the washer is definitely not movable so should i try the double nut method to remove the stud? do i need to take any precaution in particular when removing the stud? Thanks Link to comment Share on other sites More sharing options...
cruiser54 Posted December 14, 2012 Share Posted December 14, 2012 A 7/32 box end wrench should hold the stud. It's an inverted Torx, Smaller than an E8. Funny you should ask. Last night I was fumbling through my bucket of Jeep bolts and I ran across the stud you mention. I took it over to my toolbox and found the socket that fit. I was thinking to myself that someone will probably wanna know the size fo that some day. Funny...... Link to comment Share on other sites More sharing options...
fiatslug87 Posted December 15, 2012 Share Posted December 15, 2012 Be careful when removing the Torx stud, I broke the end off mine and had to use vise grips to remove it. Luckily there are lots of XJs at the JY. Link to comment Share on other sites More sharing options...
last254 Posted December 19, 2012 Author Share Posted December 19, 2012 so finally had time to finish it thanks for that size i needed thanks cruiser but i did the tps test today and its reading a very large amount of ohms anywhere from 10 to 60 so can you provide the instruction sheet for that i didn't see it under your write ups Link to comment Share on other sites More sharing options...
cruiser54 Posted December 19, 2012 Share Posted December 19, 2012 RENIX TPS ADJUSTMENT Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up. IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed. MANUAL TRANSMISSION: RENIX manual transmission equipped XJs have only a flat three-wire TPS mounted on the throttle body and it provides data input to the ECU. It has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over. Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage. AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles, as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES. However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU. FOR AUTOMATIC TRANSMISSION RELATED ISSUES: Check the square four-wire connector side of the TPS. If you have ENGINE ISSUES check the flat three-wire connector side of the TPS. For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced. Revised 09-22-2012 Link to comment Share on other sites More sharing options...
last254 Posted December 20, 2012 Author Share Posted December 20, 2012 this happened: IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed. what modifications will be needed to be done to the sensor ground harness thanks! Link to comment Share on other sites More sharing options...
cruiser54 Posted December 20, 2012 Share Posted December 20, 2012 this happened: IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed. what modifications will be needed to be done to the sensor ground harness thanks! Find your Intake Air Temp sensor. It's the sensor just to the rear of the throttle body, has 2 wires, and screws into the intake manifold. Where it's connector plugs into the harness you will see that one of the wires on the harness side is brown with a white stripe. Follow the brown with white stripe wire back into the harness. You'll have to open up the split-loom plastic sheathing to follow it. It will come to a splice with 2 other brown with white wires with duct tape over them. They're from the TPS and the CTS. The 3 wires will be spliced to a single wire headed toward the C101 connector if you have an 87 or 88. If you have an 89 or 90, you do not have the C101 bulkhead connector. Now go to the MAP sensor. Follow the brown with white wire into the harness from there. You will find a splice with 2 more brown with white wires with duct tape over them. At the splice you will find the 3 wires connected to a single brown with white wire going toward the C101, or just along the firewall towards the engine if you have an 89 or 90. Along with the MAP sensor that you traced, they are the ECU sensor ground port and the diagnostic connector on the passenger inner fender. You now have 2 sets of 3 brown with white wires, one near the firewall and one near the engine. Cut the splices out of each set of wires eliminating not only the crappy factory splices, but also the single wire between them. Bring both sets of 3 wires together. Solder the 2 sets of wires together and insulate them properly with tape or shrink tubing. Zip-tie up your new sensor loom to allow for engine movement. I prefer to cover it with some new split-loom or wrap it neatly with electrical tape when done. Revised 03-09-12 Link to comment Share on other sites More sharing options...
last254 Posted December 20, 2012 Author Share Posted December 20, 2012 awesome thanks ill do it tomorrow Link to comment Share on other sites More sharing options...
cruiser54 Posted December 20, 2012 Share Posted December 20, 2012 The number of wires can vary from year to year but don't let that bother you. It will be quite obvious what you need to do. Hey, since yo have an 87, and you're gonna be in that harness anyway, it wouldn't be a bad idea to route your CPS wires so they don't go through the c101 anymore. That is, if the factory bypass was never done. Just a thought. Link to comment Share on other sites More sharing options...
last254 Posted December 20, 2012 Author Share Posted December 20, 2012 did the harness ground upgrade and am now at a steady 1.8ohms is this ok or should i replace the tps? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 20, 2012 Share Posted December 20, 2012 The higher ohms are coming from the harness, not the TPS. Did you refresh the engine dipstick ground stud and associated wires there? That's where the circuit terminates. Any change in ohms reading when wiggling the harness? Link to comment Share on other sites More sharing options...
last254 Posted December 21, 2012 Author Share Posted December 21, 2012 yes i did the dipstick ground stud and i recrimped the wires going there as well as cleaning the area off like your write up says but there is no change in ohms when wiggling Link to comment Share on other sites More sharing options...
cruiser54 Posted December 21, 2012 Share Posted December 21, 2012 Could be just your meter then. Got another one to compare readings with? Link to comment Share on other sites More sharing options...
last254 Posted December 21, 2012 Author Share Posted December 21, 2012 ok so grounds are good ohms value now and i adjusted the tps the idle was high so i proceeded to turn it clockwise then back it off to the correct reading which was done but then i pulled a bonehead move and tightened it to tight and it cracked the tps but not badly just at the mounting point either way i couldn't get a output voltage so i went and got a new tps still no output voltage but still getting reference voltage is it possible that i messed up the connector by backprobing it because i did backprobe probably 4 different times and i still can't get an output voltage but still a solid 10 for reference voltage Link to comment Share on other sites More sharing options...
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