ComancheKid45 Posted January 12, 2011 Share Posted January 12, 2011 Alright, well my MJ left me stranded for the 1st time last night, 30 miles from home. Ive pretty much narrowed it down to the CPS (again) or the Coil. However i found this plug and sensor right above the oil pan on the drivers side wasnt in happy shape at all but I have no idea what it is or if it would have anything to do with my no start issue. I circled it for you guys, the plug on the bottom left is for the O2 sensor... Thanks for any help. 88/4.0/AW4/4x4 Link to comment Share on other sites More sharing options...
mjeff87 Posted January 12, 2011 Share Posted January 12, 2011 knock sensor..... Link to comment Share on other sites More sharing options...
Akula69 Posted January 12, 2011 Share Posted January 12, 2011 :agree: If not torqued down to the right in/lbs it will send wrong signals to ECM and engine will run like crap. The plastic sleeve is fragile at best, and after market replacements (I was never able to find an exact OEM replacement) are priced starting at 70.00. The newer ones look different, and are more strongly built (IMHO) Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 12, 2011 Author Share Posted January 12, 2011 Well the plastic sleeve was all but falling apart in my hands last night. The sensor itself is in pretty crummy shape, but would that cause the truck to just shut off (it was ideling fine, no misses or nothing) and not refire?.... I'm gonna try swapping out the coil, CPS and the knock sensor and see where that gets me.... So ill dig into it alittle later on today. Thanks Again. Link to comment Share on other sites More sharing options...
Akula69 Posted January 12, 2011 Share Posted January 12, 2011 Well the plastic sleeve was all but falling apart in my hands last night. The sensor itself is in pretty crummy shape, but would that cause the truck to just shut off (it was ideling fine, no misses or nothing) and not refire?.... I'm gonna try swapping out the coil, CPS and the knock sensor and see where that gets me.... So ill dig into it alittle later on today. Thanks Again. I've never had it cause the truck to not start, but it sure runs like crap when its not there.. The actual behavior is more along the lines of some serious engine misses and backfiring. The NO. 1 culprit for "just dying and won't start" is the CPS. Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 12, 2011 Author Share Posted January 12, 2011 Just swapped the CPS to no avail... Have swapped Coils, Ballast Resistor and Relays so far. I'm working out in the cold....I'm gonna try the MAP sensor as well. It cranks and reeks of fuel, but i see no leaks or signs of a leak anywhere.... Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 13, 2011 Author Share Posted January 13, 2011 The CPS was not it, i pulled 1 from my 89 and swapped it in, nothing.... Reinstalled back into the 89 and the 89 fired up and ran normal as before. Gonna swap the MAP sensor and the Knock sensor tomorrow....those are about the only 2 i havent tried that would possibly make any difference. Ill work on it again tomorrow.. Link to comment Share on other sites More sharing options...
mule13 Posted January 13, 2011 Share Posted January 13, 2011 if you buy a new knock sensor it won't look like the old one, but it works, least the one they gave me didnt look like the one i took out but the guy said it was the right one so i went home and ionstalled it and it worked great :) Link to comment Share on other sites More sharing options...
kyleag89 Posted January 13, 2011 Share Posted January 13, 2011 You say it cranks and stinks like fuel, but does it have spark? Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 13, 2011 Author Share Posted January 13, 2011 Yep it cranks over fine, and theres no spark from the coil.... Link to comment Share on other sites More sharing options...
SW86 Posted January 13, 2011 Share Posted January 13, 2011 thats the very sensor that i took out thinking it was the CTS for the gauge swap but wasnt. i don't remember what. it fell apart in my hands and had like a blue gel around it. i said f*ck it and plugged it back in bare metal and all oh and sorry about your ride :fs1: Link to comment Share on other sites More sharing options...
kro10000 Posted January 13, 2011 Share Posted January 13, 2011 IIRC there is an ignition pickup located under the dizzy cap and rotor that could be the culprit Link to comment Share on other sites More sharing options...
vaquaro Posted January 13, 2011 Share Posted January 13, 2011 ICU (I think thats the correct ) malfunction causes symtoms simular to a coil going bad , I had the same break down you discribe and my local shop traced it to the "ignition control module ". Replaced it and it's run fine since . :thumbsup: Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 13, 2011 Author Share Posted January 13, 2011 Where is the ICM (ICU) located on our trucks? I plan on diagnosing the Cap/Rotor and distributor area this evening......It is a Renix engine and Theres not a whole lot that goes into making it run, lol Its just a puzzle for me for the time being. :doh: Link to comment Share on other sites More sharing options...
Akula69 Posted January 13, 2011 Share Posted January 13, 2011 I have never heard it called that (I call it the stator) but its located under the metal plate inside the distributor. It has a plug from the engine bay harness that should be right around the bottom of the distributor, and it cannot be replaced without pulling the distributor and disassembling it from the bottom up. You probably know this, but I'll post it anyways: To save grief later on: BEFORE you pull the distributor you might want to chock the wheels and place the truck in neutral (without starting it) and manually rotate the crankshaft until #1 cylinder is TDC (pull the #1 spark plug and check to be sure - I6 crankshafts have to make two revolutions before TDC is complete). Then - do not rotate the engine while the distributor is out. Once out, remove the small screws inside the distributor that holds the stator, then (using a small punch) remove the pin holding the gear at the bottom of the distributor and slide the base off. The stator will be inside, and assembly is the reverse. When you re-install the distributor in the engine the rotor should be at your 5:00 position (when you are standing by the passenger side fender) or approximately 1/4 - 1/2" past the distributor cap post for the #1 spark plug wire. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted January 13, 2011 Share Posted January 13, 2011 Cam position sensor located in distributor. Will cause no spark. Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 13, 2011 Author Share Posted January 13, 2011 Its it part of the Ing. pickup? or a standalone sensor? possibly something else i can look into. thanks! Link to comment Share on other sites More sharing options...
Akula69 Posted January 13, 2011 Share Posted January 13, 2011 Its it part of the Ing. pickup? Yes Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 14, 2011 Author Share Posted January 14, 2011 Alright, I got it into the Garage tonight with my 89 and swapped the following parts back and forth to no avail. Ign Coil and Control Unit Distributor Crank Posistion Sensor Main plug wire All 3 Relays I have power coming into the coil but am getting no spark from the coil. I put my Crank sensor from my 88 into the 89 and the 89 runs as good as always so ive definently ruled that out. My last option is the ECM under the dash, otherwise i have no idea what else sends a signal to the coil for spark???.....Any help or suggestions is appreciated guys, Thanks A bunch! Link to comment Share on other sites More sharing options...
maddzz1 Posted January 14, 2011 Share Posted January 14, 2011 Isnt there a TSB out there about bypassing the C101 connector for something like this? Link to comment Share on other sites More sharing options...
kro10000 Posted January 14, 2011 Share Posted January 14, 2011 Have you tried the ignition pickup yet? Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 14, 2011 Author Share Posted January 14, 2011 Have you tried the ignition pickup yet? Yes, I swapped the entire Distributor assembly including the pickup from 1 truck to another with no success... Link to comment Share on other sites More sharing options...
Akula69 Posted January 14, 2011 Share Posted January 14, 2011 There is a spark checking tool (I believe that it is sold at Autozone) that is used inline between the items being checked. I mention this for two reasons: 1) If you plug it in between the coil and the coil wire, it can give positive proof that the coil is producing. 2) If you plug it in between the wire and the dictributor, it can give proof there is not a hidden break in the coil wire. If you know both parts of the coil are good....then the signal must be getting to the distributor. If you have swapped a known good distributor and it still will not start, and : 1) You have checked and found spark at the individual plugs 2) You have checked the fuel rail for pressure and have a consistant 40 PSI, and there is gas present in the cylinders after you attempt to crank it. 3) You have replaced the CPS. 4) You have not removed the distributor and re-inserted it off timing (see earlier post). Then I would suggest that the ECM is either not receiving signals correctly due to a wiring harness or fuse problem (check harness wires by distributor?) or the ECM itself has bit the dust. There are other sensors that come into play as far as thier function, but most would not prevent a start, they would just make the truck run like crap. Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 14, 2011 Author Share Posted January 14, 2011 We have just been using a spark plug in the wire directly off the coil to check for spark, with no luck. My next option is 2 begin tracing wires via the FSM Diagram and possibly be swapping out ECM, although that doesnt seem like a quick job with its location... Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 15, 2011 Author Share Posted January 15, 2011 ALRIGHT! I finally made some progress this evening. I swapped out the ECM from my 89 and got the truck to Fire up....yay. However it wasnt running 2 well at all and I'm almost certian thats due to the broken knock sensor. I have 2 reset the timing again and make sure itll clear up after i swap out the knock sensor but as of tonight I'm calling this whole problem due to a Failed ECM! Link to comment Share on other sites More sharing options...
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