1997 F super duty, 7.3l turbo diesel, auto trans ,328,000 miles . 14,000lbs + on scales. Been running fine til yesterday , no recent changes or mods , in fact no mods at all . Trans has about 50,000 on it. Yesterday it eas fine in the morning , mid day it was about 95F outside truck had just made 40 mile part run no problems . shut it off at job fixed equipment ( about 45 mins) started up and engine was loooping like had a drag cam in it , no smoke out tail pipe ( never did this before) shut it down checked oil and changed fuel filter , old one was fine but thought I might get lucky ) started back up ran fine thought great that was a quick fix . Pulled off job shift to second , no problem , 3rd no problem 4th no problem easied off throttle it downshifted to 3rd but i was not on hill or slowing down at 45 mph in 3rd truck was turning around 3 grand (ouch) back in throttle never shifted to forth . onand off throttle several times engine reved but trans never engaged . Od light started flashing. Pulled over about 3 miles down the road shut down and got out scan tool ( its a cheap one but usualy works for me considering most of my repairs are to equipment or company trucks) hooked it up and scaned no codes . Started truck and watched live data drove truck 14 miles never acted up again. Then at traffic light truck stalled out . It started right back up but was Camming again .No codes , Looked at IPR duty cycle , oil temp, HPOP psi, Map sensor, EBP sensor , engine timing , everything looked normal , but engine would not rev up at all. Shut it off Started back up Ran Fine. 25 miles home it shut off 3 more times never stored a code. The only things that look out of wack to me were Map sensor only read a max of 4.7psi boost all the way home EBP read about 35-50 the whole trip. My oil temp was fine but ECT showed -40F, IAT showed -40F .
It is my understanding that automatic trucks do not read ECT , there for only have the single wire sender by water outlet/thermostat for gauge. When i got home I searched and found a second single wire sensor on Passenger side of water pump behind tensioner pulley. I unhooked it figureing that if that was ect i should get a code , Nothing, shorted wire to ground - no change in gauge , no cel, no code , no change to any reading i could find . Hooked it back up no change to truck at all.
Today truck would start fine run fine get up to opertating temp fine after 10 miles or so it would act up again. Still no cel or codes and nothing unusal that I could see. Called Napa and got ECT sensor they had listed for truck figureing I could locate it by looking at new sensor ( it was only 12 $) I swear the sensor that they gave me is Oil temp in HPOP resivor so I took it back.
Not sure what to look for , the only mod on this truck is a reusable air filter and it has been there for 50,000 miles . The intake air temp sensor is in the open air box and when un hooked never changes the readings on it either but I have read that on automatic trucks the signal was ignored by pcm .
Need help Bad .Its realy bad when the mechanics truck is broke down . I am not perfect but I am no newbie when it comes to this stuff and this one has me stumped !!!! Dont like throwing on parts I dont need but thinkin maybe faulty cam sensor . Any opinions would be greatly aprecitated ( except for picking on punctuation and spelling) Like I said I am no where near perfect.

 

so drove truck today 8 miles to jobsite never stalled but did have problems shifting and 23 times the engine just went to idle . If i lifted off throttle and steped back into it (not hard , just to point i had been holding at) engine sprang back to life and went on Then with in a minute or so problem would repeat. So i pluged in scanner , no codes , ( i know this is not smart ) drove the rest of the way watching ipr duty cycle and hpop psi , as well as oil temp.
Oil temp was steady at 210 the whole time . Every time engine went to idle IPR duty cycle went to 7.1% let off hit pedal again it would return to normal 25 -45 % depending on load road speed ... HPOP psi would fall to around 400psi +or- 100 psi . Let out hit it again go right back to 680 or more again depending on conditions like speed ,load .......
Made it to job still no codes .
Started up after being off for 3 hours and then drove 35 miles (part run and back home ) not one problem the whole way ....
Any help would be greatly apprecatied .
ps. When i got home I ohmed out the TPS and could not find any dead spots or drop outs .

 

Still haven't found an answer , I did replace map sensor which corrected those readings and that helped some but still having issues . Need some ideas please help

 

First of all, Do you have a good diesel shop near you, Im not saying go get it fixed by them, but I have a snap on solus and it helps get codes that the cheap tools could not possibly get. Its also great to see live data from it like seeing cylinder power output. It kind of sounds like you are having an intermittent fuel pump issue. Also look at your gas gauge, see if at a specific level of gas this is happening. you might also want to check your uvch harness and wiggle it around or replace it, it is not that expensive, and the usual sign of it dying is a lope sound. Hope his helps, pm me or post on your page if you need further assistance.