grizer Posted April 30, 2006 Share Posted April 30, 2006 Hi , folks. Need help, next thing may be dynamite. Milage, 135.000, has been maintained properly. Last week, cut off and would not crank back up, engine would spin, no fire from coil, (but did have voltage to ignition module) :headpop: after it sat overnite, cranked and ran about four to ten minutes and shut down, (no fire). This cycle has continued for last week. I feel something is heat sensitive and replaced coil first, (even tho it checked out), next ignition module, whats next that could do it, that is exposed to heat?. Bought two new relays and went thru them in all positions, (no change). Had correct voltage, (five volts) to distributor and would pulse when engine was cranked. Have checked and ohmed out all sensors and are winthin specs, hot or cold, fuel pressure is correct. Replaced ECU and it cranked and ran and cut off the same, then would not run at all, (no voltage to dist), tried second ECU, eould not run at all. Put in old ECU and ran and cut off like it has done all week. As a last resort, changed out distributor, thinking maybe module could be getting heat soaked, but no, still will run about five to fifteen minutes and shut down, no fire from coil, will sometimes crank back up in fifteen minutes and sometimes takes an hour or so. Have checked all wires and connectors and have tried all combinations of components that I bought and evidently didn't need. Oxy sensor was past due to be replaced so I exchanged it, It would have nothing to do with my problem. Just to crank up and run, some of the sensors, (if bad) could not shut engine off, (may run rough, but would still run. When it runs, it runs qiite well. I have good factory manual with wiring diagram. If anyone has any ideas, please respond. I have been told that this is a combo of american motors and chrysler, (first year for 4.0) and has had problems. :headpop: :mad: Thanks Robert Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 30, 2006 Share Posted April 30, 2006 If nobody here can help you, post on www.jeepforum.com in the comanche section. 'Ed in North Ga' will respond, and he knows EVERYTHING about renix 4.0s, it seems. Otherwise, I can't do anything for you. Link to comment Share on other sites More sharing options...
ejndssn Posted May 1, 2006 Share Posted May 1, 2006 this may work for you :idea: we repaired a similar problem with an xj 88 and we replaced the CPS over the tranny with a bone yard donor and got his xj running with no problem vice paying someone to trouble shoot and not even gaining any ground. not saying that this is the cluprit but worth a try. Link to comment Share on other sites More sharing options...
87manche Posted May 1, 2006 Share Posted May 1, 2006 CPS. If the CPS goes bad you will have no spark. Have fun replacing it. Gonna need a few wobble joints, and about 2 feet of extensions. Don't drop the bolts into the bellhousing. Good luck. Link to comment Share on other sites More sharing options...
Eagle Posted May 1, 2006 Share Posted May 1, 2006 CPS. If the CPS goes bad you will have no spark.Have fun replacing it. Gonna need a few wobble joints, and about 2 feet of extensions. Don't drop the bolts into the bellhousing. Good luck. X2 Sounds like a classic CPS failure. Link to comment Share on other sites More sharing options...
grizer Posted May 1, 2006 Author Share Posted May 1, 2006 Hi, thanks for responses, my manual just calls it a speed sensor, what do you mean by CPS? With engine warm, it reads about 200 ohms, book calls for 200, + or -75. In this long :headpop: session I've checked it several times, will replace it tomorrow, would have allready if it was easy. I've thrown enough money at it to burn a wet mule, if it was in dollar bills. :oops: :mad: Link to comment Share on other sites More sharing options...
512tr Posted May 1, 2006 Share Posted May 1, 2006 CPS=Crank Position Sensor, but in the Renix it's called Engine Speed Sensor. The CPS don’t have to be 100% dead, but work a few minutes after start up and then shut off, causing no spark….so your symptoms indicates a CPS failure. Link to comment Share on other sites More sharing options...
Eagle Posted May 1, 2006 Share Posted May 1, 2006 I've had two Renix CPSs fail, and both gave me readings that were within spec, yet would not produce any spark. But I had to read the resistance at room temperature. I dunno how the factory expects you to test a CPS with the engine at normal operating temperature when the engine won't operate ... but let's not go there. I carry a spare in each vehicle. Link to comment Share on other sites More sharing options...
grizer Posted May 2, 2006 Author Share Posted May 2, 2006 Thanks everyone, :bowdown: changed speed sensor and seems to be ok. :D Put ohm meter on unit, waved a torch by it and it went bonkers :nuts: then goes back to correct reading when cool. Would have changed it sooner but I'm 71 with joint problems, had to get young friend to do it. :bowdown: I do have spare parts now. ;) Link to comment Share on other sites More sharing options...
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