I'm having a VERY strange issue with my '02 Supercharged Harley F-150. I picked up the truck from an auction and now I know why it was cheap! It's haunted by a gremlin which causes the speedo to read roughly x3 the actual speed which really screws up the shifting, plus the motor shuts off once the speedometer reaches 112mph or I would estimate around 40mph actual. I have it at a ford HP shop in Austin, and we have replaced the ABS sensor in the rearend, and the ABS module. Neither of which helped one bit. The strange thing is when you read the speed from the obd2 it shows accurate. SO, the cluster reads high which is some how telling the incorrect speed to the trans. Any one have any ideas?? Throwing parts at it is getting expensive. Everything looks stock from what I can tell, minus the intake. Thanks in advance!

 

Did it come with a tuner or a custom tune? This can happen if the wrong gears or tire size is entered in a tune.

 

The motor is possibly shutting off as it thinks it's reached the rev limiter or governor.

 

I'm not sure if its tuned or not, any way to tell? I'm sure the governor is kicking in since it thinks it's going that fast. The guys at the shop can't figure it out, and everyone else I have asked doesn't have any ideas from what we have tried. Sucks having a supercharged truck that you can't even drive!

 

The motor shuts off, or just does not accelerate anymore ?

Did you check the Turbine shaft speed sensor & the output shaft speed sensor ?

These are what feed the PCM for shift scheduling Tq converter engagement and EPC pressure.

These sensors are from the PCM, through the DTR ( Digital Trans Range Sensor ) back to the PCM. Might also be worth checking the connector on the side of the trans for the DTR, to make sure it is not corroded.

If you hit the rev limiter ( on the NA 5.4L ) the engine will flutter, not shut off.

what are you seeing for boost when this happens ?
- Just a SWAG that if boost is too high at the restricted shift, this could be causing the PCM to shut off the motor, if it is actually going to 0 RPM, not just fluttering.
- Just another thought, is there a boost bypass installed by the PO ?

If the TSS & OSS sensors check out, you might need to drop the trans pan, and see if the shift solenoids are OK or if the PO tried to modify them with a drill out DIY type shift kit.

Might want to search the Lightning forum, I seem to recall it is the same 4R100 trans in the HD & L. someone might have seen this issue over there already with some info or better suggestions than my SWAGs.