Dadinator Posted October 24, 2011 Share Posted October 24, 2011 So, the MJ dies when cold. After it's warmed up, it's OK. It starts back up. Particularly when its cold and you go down my long driveway, in 1st or 2nd, then get to the bottom and push in the clutch and dies. Starts back up OK. I cleaned the IAC and throttle body. Any other ideas? Link to comment Share on other sites More sharing options...
gl1200aman Posted October 24, 2011 Share Posted October 24, 2011 map sensor? Maybe the IAC is bad? I have tried to clean them on the 2 comanche's that I bought and it didn't help but after replacing them they worked good. www.teemcherokee.com has them for just under $57 plus shipping. Link to comment Share on other sites More sharing options...
Dadinator Posted October 24, 2011 Author Share Posted October 24, 2011 Would either one of those make it only die when cold??? I actually replaced it first along with the throttle body from my donor XJ. Though they could be bad too. Link to comment Share on other sites More sharing options...
Eagle Posted October 24, 2011 Share Posted October 24, 2011 So, the MJ dies when cold.After it's warmed up, it's OK. It starts back up. Particularly when its cold and you go down my long driveway, in 1st or 2nd, then get to the bottom and push in the clutch and dies. Starts back up OK. I cleaned the IAC and throttle body. Any other ideas? Live with it. It's a peculiarity of the Renix system. The dealers even had a name for it: "Early morning drive-off stall." My '88 XJ has always done this, and I bought it new. A couple of years after I bought it, my dealer had retired and sold the business to a pair of crooks, so I switched to another Jeep dealer for service. The service manager there talked me into having the C101 connector (which your '90 doesn't have) bypassed. He promised me it would improve starting, improve gas mileage, cause beautiful women to throw themselves at me -- and cure "early morning drive-off stall." The work was covered by a TSB but, unlike a recall notice, the customer pays for TSB work. IIRC, it cost me $500 -- and that was back when $500 was worth something. Naturally, it didn't fix any of the things he had claimed it would, and when I confronted him later he absolutely denied having told me any of what I remembered. Needless to say, I no longer go to that dealer for service. The point of all that being ... you are not alone in having that issue and, if you have it, just live with it because there isn't any living person who really REALLY knows either what causes it or how to fix it. Link to comment Share on other sites More sharing options...
gl1200aman Posted October 24, 2011 Share Posted October 24, 2011 From what I have seen it could, it controls the fuel richness. I had one that idled low and one that reved to 1800 rpm's. Cleaning them did not help so I replaced them and they worked great. When I replaced them I also drove them at 40 mph or faster for 20 min. which helps them self adjust. Have you checked the MAP sensor or the TPS? Link to comment Share on other sites More sharing options...
Dadinator Posted March 16, 2012 Author Share Posted March 16, 2012 Long time, but it's fixed. Someone on the Jeepforum was having a similar issue. The issue is the fuel pump ballast resistor. Some bypass it. I have a donor, so I just pulled the one off the XJ. It idles better than it has in years and doesn't die anymore. Simple fix. Thought folks would want to know in case they are having the same problem. So, Eagle... Don't live with it. Fix it. There is now a living person who knows what it is! Me! :wrench: Link to comment Share on other sites More sharing options...
1987Comanche Posted March 16, 2012 Share Posted March 16, 2012 There is another possibility. You might need the revised ECU. I was lucky enough to score one at the jy and it works great!! See Text file below for TSB Models 1987-1990 MJ & XJ Bodies With 4.0 Liter Engine Subject Start and Stall and Driveway DieOut Index DRIVEABILITY Date December 29, 1989 No. 18-54-89 REVISION A P-0005 (C18-24-9) BODY CODE LEGEND MJ - COMANCHE XJ - CHEROKEE NOTE: THIS TECHNICAL SERVICE BULLETIN SUPERCEDES TSB 18-54-89 WHICH SHOULD BE REMOVED FROM YOUR FILES. SYMPTOM/CONDITION Driveway die-outs with a cold engine, particularly in warm ambient temperatures. DIAGNOSIS Verify that TSB 18-51-88 or TSB 18-57-89 (crank position sensor and patch harness) has been properly performed on the vehicles to which they apply. Make sure the fuel management system is operating correctly by using the DRB II in the state display and systems test. Any electronic engine control problems detected by the DRB II must be corrected before performing this TSB. PARTS REQUIRED 1 ECU (Automatic Transmission) PN 53007842 1 ECU (Manual Transmission) PN 53007843 1 Mopar Choke and Linkage Cleaner PN 4549619 This repair procedure involves replacing the ECU and cleaning the throttle body. 1. Install the new service replacement ECU. 2. With the engine off, remove the clean air tube from the throttle body. 3. Open the throttle and spray the bottom edge of the throttle plate and the throttle body bore with Mopar Choke and Linkage Cleaner, PN 4549619, (use cleaner sparingly). NOTE: USE ONLY THE RECOMMENDED CLEANER TO PREVENT DAMAGE TO THE THROTTLE SHAFT SEALS. 4. Using a soft bristle brush such as a tooth brush, work the cleaner into the stubborn deposits on the throttle blade and the throttle body bore where the throttle blade is positioned at idle. Allow the cleaner to soak for three (3) minutes. 5. Start the engine and let idle. Spray the cleaner sparingly at the throttle plate edge and throttle bore contact area. 6. Operate the engine at 1500 RPM for one minute to clear the intake manifold of cleaner. Allow the engine to idle until it reaches normal operating temperature. Then shut the engine off. 7. With the engine off, connect the DRB II to the vehicle. 8. Disconnect the idle speed stepper motor wire harness connector at the stepper motor. 9. Connect the stepper motor exerciser tool 7558 (Ele. CT01) to the stepper motor. See Figure 1. 10. Set the parking brake, place the transmission in park or neutral and start the engine. 11. While observing the RPM on the DRB II, put the exerciser tool control switch in the low position until minimum idle speed is obtained. 12. With all accessories off, adjust the base engine idle speed to 575 rpm in neutral. This should be accomplished by first adjusting the throttle body air by-pass screw and then, if necessary, by adjusting the throttle stop screw. 13. Adjust the throttle position sensor so that the "state display" on the DRB II displays the throttle position sensor as 12-14%. If the TPS percentage is above or below this number, refer to the TPS adjustment procedures as displayed on the DRB II or as outlined in the appropriate Jeep Service Manual. 14. Shut the engine off. Install the clean air tube, remove the stepper motor exerciser control tool, connect the idle speed stepper motor wire connector. Spray the exposed threads of the throttle stop screw with cleaner and blow dry with shop compressed air. Apply Loctite 209 or equivalent to the exposed threads. See Figure 2. POLICY: Reimbursable within the provisions of the warranty. TIME ALLOWANCE: Labor Operation No. 08-15-62-93 . . . . . . . . . . . . . . . . . 1.0 Hrs. FAILURE CODE: 04 - Cold Stall Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 16, 2012 Share Posted March 16, 2012 Long time, but it's fixed.Someone on the Jeepforum was having a similar issue. The issue is the fuel pump ballast resistor. Some bypass it. I have a donor, so I just pulled the one off the XJ. It idles better than it has in years and doesn't die anymore. Simple fix. Thought folks would want to know in case they are having the same problem. So, Eagle... Don't live with it. Fix it. There is now a living person who knows what it is! Me! :wrench: The fuel pump ballast resistor's value is about 1.3 ohms. It's bypassed when starting so the fuel pump gets full battery voltage, then is relayed into the FP circuit to lower the voltage to the pump which prolongs it's life and lowers the operating noise. A corroded terminal on the ballast resistor can cause an ohm or two resistance by itself. I think you just lucked out replacing the ballast resistor because by unplugging and replugging the spade connectors you wiped out some corrosion resistance. I hope not, but I think you have a temp fix mate. :cheers: Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2012 Share Posted March 16, 2012 Long time, but it's fixed.Someone on the Jeepforum was having a similar issue. The issue is the fuel pump ballast resistor. Some bypass it. I have a donor, so I just pulled the one off the XJ. It idles better than it has in years and doesn't die anymore. Simple fix. Thought folks would want to know in case they are having the same problem. So, Eagle... Don't live with it. Fix it. There is now a living person who knows what it is! Me! :wrench: The fuel pump ballast resistor's value is about 1.3 ohms. It's bypassed when starting so the fuel pump gets full battery voltage, then is relayed into the FP circuit to lower the voltage to the pump which prolongs it's life and lowers the operating noise. A corroded terminal on the ballast resistor can cause an ohm or two resistance by itself. I think you just lucked out replacing the ballast resistor because by unplugging and replugging the spade connectors you wiped out some corrosion resistance. I hope not, but I think you have a temp fix mate. :cheers: Interesting. My wife complained the other day that her Cherokee was acting like it did just before the fuel pump went out a while back. I did the usual connector checking and found that the connectors at the ballast resistor weren't real tight. I removed them from their plastic housing, squeezed the sides a bit and put them all back together. No more problem. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2012 Share Posted March 16, 2012 This never hurts and can only help: 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, and adding dielectric grease before plugging it back together. 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 dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else. Revised 03/15/2012 Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 16, 2012 Share Posted March 16, 2012 This never hurts and can only help: 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, and adding dielectric grease before plugging it back together. 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 dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else. Revised 03/15/2012 To clarify, dielectric grease is non-conductive sealant and it's purpose in life is to prevent contaminant entry (like H2O) into electrical connectors, spark plug boots, etc. It should never be used on any shiny metal-to-metal connector pins or relay terminals after cleaning as it will add resistance. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2012 Share Posted March 16, 2012 I wonder what that crap was that the factory used that left the white hardened residue on the connectors. I will change my write-up if you're absolutley sure of this. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2012 Share Posted March 16, 2012 After reading this and a few others, I'm not sure that leaving the dielectric grease out/off is a good idea, especially in hostile environments. http://www.epinions.com/review/Loctite_ ... 40932?sb=1 Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 16, 2012 Share Posted March 16, 2012 Worked in military Cal Labs for many years. Automotive, aviation, RF, VHF, and micro-electronics. Use of dielectric grease on any shiny metal-to-metal contact in a connector, be it a single or multi-pin connector, high or low voltage, AC/DC, high or low frequency, whatever, is a strict MILSPEC verboten in any environmental application as dielectric grease is non-conductive. Read resistance. It's a sealant, designed to keep contaminants out, i.e. a coating for the boots, weather-tech shell, or whatever protective shield around the electrical harness joint. Use it if you wish on metal-to-metal, I don't and never will. And yes, I'm absolutely sure of this. Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 16, 2012 Share Posted March 16, 2012 Worked in military Cal Labs for many years. Automotive, aviation, RF, VHF, and micro-electronics. Use of dielectric grease on any shiny metal-to-metal contact in a connector, be it a single or multi-pin connector, high or low voltage, AC/DC, high or low frequency, whatever, is a strict MILSPEC verboten in any environmental application as dielectric grease is non-conductive. Read resistance. It's a sealant, designed to keep contaminants out, i.e. a coating for the boots, weather-tech shell, or whatever protective shield around the electrical harness joint. Use it if you wish on metal-to-metal, I don't and never will. And yes, I'm absolutely sure of this. I used it on my C101 connector............guess I should clean it out huh? What do you suggest I clean it with? Link to comment Share on other sites More sharing options...
NotMatt Posted March 16, 2012 Share Posted March 16, 2012 Interesting problem. I've heard of this being common on the HO motors but never heard of people experiencing issues like this on RENIX motors. As far as the ballast resistor is concerned, I have removed it and spliced the wires together on every renix-era 4.0 I've ever owned... my understanding is that the resistor was added to reduce fuel pump "noise", excessive whine from the pump. If you look on an 87-era rig they don't even have one. Seems like just another item that can cause problems and complicate troubleshooting. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2012 Share Posted March 16, 2012 Worked in military Cal Labs for many years. Automotive, aviation, RF, VHF, and micro-electronics. Use of dielectric grease on any shiny metal-to-metal contact in a connector, be it a single or multi-pin connector, high or low voltage, AC/DC, high or low frequency, whatever, is a strict MILSPEC verboten in any environmental application as dielectric grease is non-conductive. Read resistance. It's a sealant, designed to keep contaminants out, i.e. a coating for the boots, weather-tech shell, or whatever protective shield around the electrical harness joint. Use it if you wish on metal-to-metal, I don't and never will. And yes, I'm absolutely sure of this. I used it on my C101 connector............guess I should clean it out huh? What do you suggest I clean it with? It can't be any worse than the road tar the factory used 25 years ago. If yo really wanna clean it out, use Brake cleaner or electric contact cleaner. Tweak the receptacle pins tighter with a pick before reassembly. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 16, 2012 Share Posted March 16, 2012 Interesting problem. I've heard of this being common on the HO motors but never heard of people experiencing issues like this on RENIX motors. As far as the ballast resistor is concerned, I have removed it and spliced the wires together on every renix-era 4.0 I've ever owned... my understanding is that the resistor was added to reduce fuel pump "noise", excessive whine from the pump. If you look on an 87-era rig they don't even have one. Seems like just another item that can cause problems and complicate troubleshooting. 87s came without it but the factory issued a TSB shortly thereafter for a harness including the resistor to eliminate fuel pump noise per customer complaints. They later issued a TSB to put a pulse damper into the hose between the pump and sending unit assembly to further reduce noise. Yes, it is a source of problems. I don't know how many of them actually burn out and fail, but I was surprised to find that the connectors being "wiggly" on the resistor of my wife's XJ were causing symptoms of a bad fuel pump. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 16, 2012 Share Posted March 16, 2012 http://sw-em.com/anti_corrosive_paste.htm Good stuff. Link to comment Share on other sites More sharing options...
Dadinator Posted March 17, 2012 Author Share Posted March 17, 2012 Sounds like if I have the problem again, I'll be bypassing. I had a donor so replacing was easy and free. Link to comment Share on other sites More sharing options...
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