Re: Allison Transmission Questions
This is a tough one.
I would normally recommend a stall test, to separate engine problems from transmission problems. Start the engine, set the brakes, keep everyone away!!! Go to wide open throttle and record the speed the engine gets to. A local Cat or Allison place should be able to tell you the proper stall speed for that engine/trans combination. A low stall usually indicates engine power problems.
I would go ahead and do the stall test just to know the results. However, if the problem occurs only going down the road, and with no transmission trouble codes, I'm leaning toward an engine problem like a sensor not reading correctly. I would take it to a good Cat distributor and have them plug in the Cat Electronic Technician. Make sure all the sensors (temps, input voltage, turbo boost, throttle position, etc.) from the engine are reading values that make sense for the conditions. Sometimes a turbo boost sensor or something can fail and not be so far out of bounds it causes an engine code.
If that doesn't show anything, do the same for the transmission. Have the Allison place plug in Allison DOC and watch the sensors - temp, speeds, input voltage, throttle position sensor. Make sure the readings make sense.
Keep us posted. This one isn't an easy one. Now watch, it'll probably be something simple I should have known.