Engine hesitates or dies at 5 mph

Fordracer · February 6, 2018

I have a 2000 F-350 7.3 that will hesitate or die when taking off from a stop. It accelerates fine until you get to 5 mph and then it will hesitate or die until you go over 5 mph. The only codes are EBP codes. Made some recordings and ICP starts to drop right before RPM drops and later I noticed that the VSS drops out a couple seconds before it acts up. The VSS goes to 4 mph and then it drops to 0 for a couple seconds and then it will hesitate until you go over 5 mph and the speed signal comes back and sometimes it dies before the signal comes back. I don't know if the VSS reading is causing it or not but I put in a new rear sensor with no help, I checked AC voltage at the sensor and at the ABS module and the signal doesn't drop out. I put in a test PCM with no help. I also checked the fuel pressure at right head, it's 60 psi when acting up, put in a black cam sensor, unplugged ICP and then EBP and it made no difference. I put a complete Ford reman engine in this truck 60,000 miles ago.

I don't know if I'm wasting my time chasing down the VSS circuit or if it's something else. Has anybody else ran into this?

Fordracer · February 10, 2018

I finally have it fixed. I decided to ignore the speed signal and drove it a lot more and made a lot more recordings to pinpoint the problem. I noticed that when you first drove it with a cold engine it wouldn't act up until you drove it a mile and then it would always act up so I made some recordings when it didn't act up. Then I tried to see if going in reverse made it act up and didn't on acceleration but sometimes when you backed up and stopped it would die right when you stopped so I made some recordings when it died and when it didn't die and that's how I caught the problem. I noticed that right before you stop after backing up the IPR duty cycle would go up sharply and if the ICP didn't go up also it would die and if the ICP went up it stayed running. So I looked at the recordings of when it didn't die with a cold engine and noticed the IPR was at 15% when you took off and when it does act up the IPR is at 12% when you take off. So I guess the IPR is sticking between 12% and 15% duty cycle. Replaced the IPR and all is good.