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97 F-250 Cut out, surge, stall, and stumble
Alright, I am new to this forum so I would like to start out by saying hello to everyone and I appreciate any possible help in advanced.
So I have a 1994 F-250 (was an IDI truck) with a 1997 7.3L in it that I bought back in January. I bought it from a guy in Missouri that had a lot of information on the truck, but he was not the guy that did the swap The guy that did the swap did not do a very good job to say the least, which in result has me left with a rats nest of wiring sitting in my engine bay. I knew this when I bought the truck, but I also know that I can sort through it when I need too and make it right. Anyway, lately I have been having an issue with my truck surging under light acceleration usually followed by it cutting out very harshly. When I am coasting down to an idle it will occasionally have a really hard idle and smooth out, or it will just plain out die. My issues started about a week ago. This truck has stage three injectors, an electric fuel pump to deliver the needed fuel to the high pressure pump, studded heads, a tuner, and possibly a bigger turbo as well. Unfortunately I do not know the brand of injectors or the brand of the tuner.
So the back story of this truck since I bought it: Performed an oil change using 15W-40 Rotella, changed the fuel filter/water separator, replaced batteries. After all of this the truck ran great and had tons of power and would push 35 PSI of boost when I hammered on it. We put the truck on the Dyno at school and it proved to be very impressive as it made too much uncorrected torque for the dyno to handle (humble brag lol). At this point in time I had nice dark black smoke coming out of the pipes, the only issue I had with the truck was that the tuner would occasionally quit working and I would go from having 4 seperate tunes to only having high idle and one other tune, I didnt think much about this because it didnt cause any drive-ability issues. Then came my first trip towing with the truck.
When the issues started. I headed to Tennessee with my trailer and made the mistake of not looking over the truck before I went, (I always check over the tow vehicle before I leave, dont know how I didnt do it this time). I made it to the first race without an issue, but I did have the truck cut out a couple of times when I left the next morning. The next night I started the truck to let it warm up before I left and it just simply died after running for 5 minutes. I restarted it and it died almost immediately and the WTS light was blinking at me. I checked for fuel pressure after the electric pump at the fuel separator and I had good pressure, same story at the Aeromotive reglulator in the valley. Finally we got it running after finding the glow plug relay touching the intake piping (in hindsight i think this might have been unrelated), and it made it back home. Once back home it ran fine for a couple of days and then died again at a friends house. Once again it started after a few tries and worked fine for the day. Finally the third time it died, I talked to my friend and he and I looked at it to find that I was 3-4 quarts low on oil. He said that this would possibly make it too low for the HPOP to pick it up. After adding the oil the truck ran great and has not had that issue again since. A few days after that I had a hard idle concern along with overfueling. My friend and I found that the ICP was not reading so I replaced it which fixed the hard idle. Once again this fixed the truck for a couple of days and then the current concern started. The next issue we found was the vacuum lime to the MAP sensor had a cut in it which once again fixed the truck for a couple of days. The next step we took was cleaning up all the grounds and taking some alcohol and cleaning up some corrosion at the tuner connection in the PCM. This has made the concern happen less, but it still will cut out, surge, and rough idle every time I drive it however it no longer dies. There are 6 or 7 codes in the PCM but I did not write them down and do not remember the numbers, I do know that there is a code for Throttle Position Sensor B Circuit, Map sensor low input, a KAM code, IAT sensor circuit (the IAT is no longer on the truck), and Exhaust back pressure sensor circuit (again no longer part of the truck). There are a couple more that I do not remember.
The truck still runs fine under heavy acceleration but the smoke is a medium grey color now instead of the dark black it used to be. The truck also will only boost to 25 PSI. I figure the lower boost is due to the higher amount of fuel being used. When the truck does cut out it feels like it is cutting fuel. I just need some ideas if you guys have any, I am hoping to get it on the Dyno whie hooked up to a scope and a scan tool to see what is happening when it cuts out.