I got a 99 dodge ram 4x4 with a 5.9 360. i bought the truck because it needed a computer. i went and bought a new comp. and got it flashed to the vin and milage. it seemed to help the truck a littl after i put it on but now the truck will fire up and run perfectly when its cold, but will warm up to operating temp. then just die like u turned the key off. i try to start it after it dies and it will fire up for a split second then shuts off. i put a new iac, and tps on and nothing. ive tested the map sensor and it tests good on my volt meter. ive checked my fuses on the fuse box they appear to be good.would a bad cam sensor cause thisby chance? i would think it wouldnt be the crank sensor or i wouldnt get spark at all.. please help because honestly..im stomped

 

OK. A couple of things. Yuo need to see what is causing it to die - fuel, spark, air. You said you changed IAC. DId you disconnect battery while doing this and the other things? If not, disconnect and let set a couple of minutes. Did you clean out the IAC port in the TB when you changed it?

Also, ASD relay can cause it to shut down. Swap it with another relay and see if this helps.

Also, don't throw away the aprts you took off. Thye may not be bad.

you can go to the FAQ/DIY section and download a service manual. Parts manual there also. Very helpful.

Check those things and post back...maybe we can help you figger' this out.

 

Try unplugging the O2 sensor as well.... (pre-cat.)

 

like gdstock said, find out what the engine isnt getting. fuel, spark, or air.
the crank sensor and the cam sensor both could cause a problem like this. both ahve inputs to tell the engine when to fire. if one or both of the sensor are bad the engine is going to fire at will with no input. that being said, you would more than likely run into a missfire also. plus the sensors would be bad with the engine hot or cold so you would see these symptoms regardless of the engine temp.

check tb/iac ports. clean them up.
do a spark test on a few cyls. 2 on each bank should be good.
check fuel pressure. should be at about 49 psi

thats a good place to start.

 

Was my first thought too, since it runs good till it warms up. Check engine light not coming on, I guess?

 

I'll put my vote in for crank sensor. But do what has been suggested first.

 

i havent gotten to do a fuel pressure test yet but im thinking its fuel or air related. check engine light will come on after dies but usually stays off when i first cold start it. its just weird to me that everytime it starts, it will shut off at the exact same time every time. i had the bat. unplugged while replacing the sensors and then reset it after i put them on. i guess i will get a crank and cam sensor in a couple days and try that but i was also thinkin, would a temp sensor cause this? i also tried switching the asd around and it did nothing. WTF????

 

if your temp gauge is reading correctly, then the sensor is OK. (PCM gets its cue from the sensor, and 'suggests' to the instrument cluster what it should tell you.....)

Being consistent like that..... I would unplug the front O2 sensor, and take it for a drive, see if it still craps out at the same point.

 

so i tested it with a fuel pressure guage today and it read a constant 49 lbs. i cant figure this out its still dieng when it warms up its sucking all kinds of air and doesnt want to restart when i go to fire it back up. ive got about $800 in this ordeal

 

Crank sensor or maybe ignition coil ?