Truck in question is a 1992 Dodge Ram 150 2wd 5.2L MPFI. Well i have been through alot with this truck, first putting a trans in it, was fine for about 2 3 months, now the motor, i have done the intake gasket, new fuel pump, new IAC, O2, AIT sensor, full tune up, crank sensor, distributor pickup coil, new oil pump drive gear and the bushing in the block underneath it, cleaned the throttle body to look like new, unclogged the egr port in the intake, new egr, all new vacuum lines, pretty much the only thing not new is the MAP, TPS, Fuel pressure regulator and the injectors. I have changed the computer out with a (spare) that i aquired at the junk yard. Anywho, my problem is that the truck runs fine idle sometimes it would just stall and if it would run about 2500-3000 RPMs and above it like breaks up or kinda like intermittant spark. and it stalls will not start get a few spits and sputters but nothing. If i blow compressed air over the crank sensor in time it will fire up sit and idle repeat process. Just wondering if there could be something i am overlooking. Oh and there is a ground that the speed sensor/crank sensor and whatever else all goes to one ground in the transmission wiring harness that was all corroded i fixed that as well. Just really pulling my hair out and i have never in my life had a vehicle that everything kind of just quit at once. Any advice or help would be greatly aprreciated. Oh and the crank sensor came from advance auto parts, its the 4th one i have put in, any intell on a better dealer or where to get one that will last more than 4 days would be great....thanks for looking.

 

Throw a can of sea foam in the tank. You might get lucky if it is an injector problem. Have you tested the MAP, TPS, and fuel pressure? Does the truck set any engine codes? Have you checked voltage and resistance values in all of the engine systems? If you can get your hands on a stethoscope you can listen to each injector to tell if it is firing.

 

Well i have not tested the map or tps sensor, all the injectors are firing i listened to them with a peice of hose up to my ear, but i did find one problem the crank sensor wiring connector on the engine side of the harness one of the pin connectors was loose so i replaced it, it was the ground wire for the sensor it still shuts off at random, last night for example fired it up sat for about 5 minutes running shut off started again, then shut off would not start, battery died trying to start it in 6 degree weather, soon as i put jumper cables to it fired right up, i may have to run new ground wires for the trans harness they did not look to pretty little bit of corossion in them. But i do believe the injectors are working fine, it still runs like hell, it is throwng two codes for the trans cause i swapped the junk a518 out of the legendary A727 Loadflight trans, so much better but its just throwing codes for the TCC and the overdrive. And one other is that the engine is staying cold to long i think it just needs a thermostat but i do not see that making the truck just shut off. I really hate wiring but i love the truck and do not want to get rid of it any time soon. Thanks for the input.

 

I do not know if the map or tps would cause a crank but no start i am doing some reaserch on them cannot really find anything for my vehicle but typical google, more about a BMW than anything. I will try and test them both in a bit.

 

A bad temperature sensor can cause all kinds of intermittent problems. A bad MAP will definitely cause a no start condition but I have never heard of one being intermittent. A dead spot in the rheostat inside the TPS can cause what you describe. If you have found some corrosion in the wiring the chances are pretty good you will find more as you look. I still suggest the sea foam if the injectors haven't been cleaned in a while as they may be pissing a stream instead of spraying a fine mist even though they are firing. Any good manual will give you the info to test all of your voltages and resistances in all of your systems. Good luck.

 

I just got off work so looking into that now, i really do not want to buy a new map from advanced, all they have anymore is junk, but i gotta do something and i am definately a believer in sea foam i have not ran any throught yet just some standard injector cleaner. Thanks for all your help and advice.

 

Part replacing is an expensive way to trouble shoot unless you work at a dealer. Get a good manual and check the part before replacing it.

 

I have put two map sensors in the truck. First one i was on my way home it backfired really loud, like a shotgun outside my window, and ran fine until i was about a mile away and it shut down. So I waited a few minutes and it fired up idled fine, put it in gear to take off home and kept stalling i eventually made it but it was no easy task...lol. Next morning it started and died that was the last of it so i went to the auto parts and got another one installed it fired right up and ran fine till last night. Backfired by my house and stalled right in front had to push it into the parking spot. Now this morning it started right up and ran fine the whole way to work. I live about 15 miles from work so it definately had time to warm up. I do not know what the issue could be i cannot see getting two faulty sensors from advance. I Know the alt. puts out more voltage than i would like, could the sensors be getting to many volts and tripping them out?? Any help would be appreciated

 

I say again. "Part replacing is an expensive way to trouble shoot unless you work at a dealer. Get a good manual and check the part before replacing it."

You must also check the wiring system the part goes into.

What test did you do to make you think the MAP sensor was bad?

 

i have not tested it but i do believe that its in the wiring harness being as there were a few other problems with my wiring. What would be the best way to test the wiring with a multi meter. Last time i used two jumper wires and a test light to find broken wiring or bad grounds. It just did it to me now and i am at work, i waited like two mins and it fired back up, im really loosing patience with this thing.