88whitemanche Posted January 19, 2015 Share Posted January 19, 2015 What's up fellas So I decided to drive the comanche today and it has been driving flawlessly which to tell you the truth SCARES ME...has all the power at acceleration, no skipping of a beat, I mean I haven't felt my truck run like this a few time up until I get to the point of a backfire/shuts off/shuts on by itself in a split second....no real way to control this....not even to pull to the side or rejump it...just on like nothing happened after the shut off and backfire.... Do I really need to know for that my truck in order to perfect is to actually not run right? Everything is new, except cat haven't replaced(removed) yet, all my grounds are tight and new ones added in every aspect known, manifold bolts tight, wires not frayed or cut, cps new, plugs and wires, rotor , cap, map sensor... Any clues? Link to comment Share on other sites More sharing options...
88whitemanche Posted January 21, 2015 Author Share Posted January 21, 2015 Anyone? Link to comment Share on other sites More sharing options...
dj5 Posted January 21, 2015 Share Posted January 21, 2015 maybe cat is clogged and fills with pressure so shuts off truck?smell anything when backfiring? Link to comment Share on other sites More sharing options...
88whitemanche Posted January 21, 2015 Author Share Posted January 21, 2015 No...it only happens on the hwy at70mph....more concern about not crashing/ someone crashing into me/ get out safely.... Link to comment Share on other sites More sharing options...
nitroxsteve Posted January 21, 2015 Share Posted January 21, 2015 Is it shutting off and back on again by it self? Link to comment Share on other sites More sharing options...
88whitemanche Posted January 21, 2015 Author Share Posted January 21, 2015 Is it shutting off and back on again by it self?By itself... Link to comment Share on other sites More sharing options...
88whitemanche Posted January 30, 2015 Author Share Posted January 30, 2015 Well fellas it's not the catalytic converter... I went to remove it and it's been hollowed out... So it must be something else.... Anyone has a clue what it could be? Link to comment Share on other sites More sharing options...
nitroxsteve Posted January 30, 2015 Share Posted January 30, 2015 Sounds like it's loosing spark . How long does it shut off for? Will it do it just idling in the driveway? Link to comment Share on other sites More sharing options...
88whitemanche Posted January 30, 2015 Author Share Posted January 30, 2015 It's only happened doing 70mph on the hwy and the shutoff is a true split second and it'll start back up by itself and run flawlessly after... You don't even have time to realize to Pop the clutch/pull over to the side or anything....just you feel a sudden loss/ loan down at gauges/ backfire and rpm back to normal in speed at 70mph.... No it doesn't do it at idle In the driveway...sometimes out on the street....cps is clear from the exhaust manifold... Link to comment Share on other sites More sharing options...
nitroxsteve Posted January 30, 2015 Share Posted January 30, 2015 Does anything else go off at the same time? Link to comment Share on other sites More sharing options...
88whitemanche Posted January 30, 2015 Author Share Posted January 30, 2015 I assume just everything when it shuts off for a split second.... But you mean after it backfires? No...everything runs like butter after...it's hard to repeat the same symptoms back to back...luckily I've been able to go home and switch trucks after a week of dd driving.... I leave it parked because I'm afraid for an accident when it's shuts off while I'm in the middle of the hwy doing 70 Link to comment Share on other sites More sharing options...
nitroxsteve Posted January 31, 2015 Share Posted January 31, 2015 I was wondering if things like the radio also shut off. Link to comment Share on other sites More sharing options...
88whitemanche Posted January 31, 2015 Author Share Posted January 31, 2015 It happens so fast I don't realize the radio is on...but when it does come back on the radio is on/everything works as usual... Link to comment Share on other sites More sharing options...
nitroxsteve Posted January 31, 2015 Share Posted January 31, 2015 If you loose spark but fuel is still delivered when the spark returns it will back fire. I think your loosing spark for a split second but I don't kmow where to tell you to start looking. Link to comment Share on other sites More sharing options...
8valvehero Posted January 31, 2015 Share Posted January 31, 2015 Ok go through every connector. Starting at the coil, then going to the distributor, plugs, alternator, battery, and every other electronic connector and relay that you can possibly access- check every inch of wiring that you can see. If possible, disconnect them, shine 'em up with a wire brush and plug them back in. At very least, you will find the problem while you are looking at everything else. If everything looks cool, then get a multimeter and start doing some basic tests. It could be something super basic that you'll see immediately like a loose wire on the coil, or something like the crank sensor where you've gotta test it. Just be patient and go through every single thing that you can see. I've had to tape my multimeter to my window and drive around with it hooked up to figure some things out. Good luck! Link to comment Share on other sites More sharing options...
metrictonner Posted February 1, 2015 Share Posted February 1, 2015 I did some testing of a MAT sensor for a company that thought it had a replacement for the no longer produced 4.0 Renix MAT. Appearently their MAT was telling the computer that the air flow was too cold all the time. This caused really bad gas mileage and backfiring periodicly for what seemed no reason. I got the feeling that you could tell the ECU to cause the injectors to really dump fuel to the point of backfiring if you really wanted. So if your problem is based on bad gas mileage and your temperature gauge is not reading too low after warmup you might check your airbox heat diverter air temp sensor or MAT. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 4, 2015 Share Posted February 4, 2015 I did some testing of a MAT sensor for a company that thought it had a replacement for the no longer produced 4.0 Renix MAT. Appearently their MAT was telling the computer that the air flow was too cold all the time. This caused really bad gas mileage and backfiring periodicly for what seemed no reason. I got the feeling that you could tell the ECU to cause the injectors to really dump fuel to the point of backfiring if you really wanted. So if your problem is based on bad gas mileage and your temperature gauge is not reading too low after warmup you might check your airbox heat diverter air temp sensor or MAT. It's not that big a player in this. And when they fail, if they ever actually do, they fail indicating a high temp to the ECU. And even when the biggest player in air/fuel ratio fails, the MAP, it will burble and flood, not shut off and come back. This isn't gonna be a quick and easy one. But, there are some steps you can take to make sure what isn't causing the issue. Ever clicked on the link in my signature and reviewed my Tips? #4 could be a player here for sure. It it's an 88, I would do Tips 1 through 5 thoroughly and consider doing #27. Link to comment Share on other sites More sharing options...
8valvehero Posted February 4, 2015 Share Posted February 4, 2015 ^this^ :bowdown: Link to comment Share on other sites More sharing options...
88whitemanche Posted February 4, 2015 Author Share Posted February 4, 2015 1. Cleaned and added 5 more grounds and upgraded.... 2. Can't do...did #27 already.... 3. Will redo 4. Will reclean 5. 0 ohms Will get back to you guys with more info... Link to comment Share on other sites More sharing options...
cruiser54 Posted February 4, 2015 Share Posted February 4, 2015 1. Cleaned and added 5 more grounds and upgraded.... 2. Can't do...did #27 already.... 3. Will redo 4. Will reclean 5. 0 ohms Will get back to you guys with more info... You've done a lot of good stuff. Link to comment Share on other sites More sharing options...
88whitemanche Posted February 9, 2015 Author Share Posted February 9, 2015 Ok before I got to do any cleaning I let the truck idle for a bit since i haven't ran it in a week.... I went to clean out a section where I have jeep parts after 20mins I hear the truck bog then catch itself but didn't back fire.... I wasn't there to see what went out but I started to do cruisers tips 3 and 4.... Surprisingly it actually did it at idle or in the drive way. It only does it on the road doing 70mph...but after that bog down I can't get it to repeat itself... I'm at a loss.... Link to comment Share on other sites More sharing options...
cruiser54 Posted February 9, 2015 Share Posted February 9, 2015 "Started to do tips 3 and 4"? Link to comment Share on other sites More sharing options...
88whitemanche Posted February 9, 2015 Author Share Posted February 9, 2015 Sorry I did it after I heard it bog down... Link to comment Share on other sites More sharing options...
88whitemanche Posted February 9, 2015 Author Share Posted February 9, 2015 double post.... Link to comment Share on other sites More sharing options...
88whitemanche Posted February 10, 2015 Author Share Posted February 10, 2015 Relay center looked like this.... Link to comment Share on other sites More sharing options...
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