Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Chuck Pearson on July 11, 2022, 06:15:05 pm

Title: Q about throttle position sensor
Post by: Chuck Pearson on July 11, 2022, 06:15:05 pm
If you don't have a tps can you still shift with pad on a 3060 Allison?  i.e. shift manually?

Im sensing possible trouble with king unit, and want to prepare in advance.  Cant install air or other at this point, rotator cuff has me single handed.
Title: Re: Q about throttle position sensor
Post by: oldguy on July 11, 2022, 06:45:25 pm
The trans will ship without the TSP but properly and yes the shift pad will work.
Title: Re: Q about throttle position sensor
Post by: Dan & Annie on July 12, 2022, 04:17:42 pm
I'm curious about this also as I'm currently in the middle of the conversion from King Controls to air throttle. My question is why does the transmission care what the throttle position is? Wouldn't speed and RPM's provide enough info for the transmission to know what to do? (Where it gets that information I don't know, but it must from somewhere.)
Title: Re: Q about throttle position sensor
Post by: Doug W. on July 12, 2022, 04:43:51 pm
From what I understand without tps up shifts happen at max rpm, like 2600 to get into 6th. Also have heard down shifts can be hard.
Title: Re: Q about throttle position sensor
Post by: oldguy on July 12, 2022, 05:02:50 pm
The trans needs to know how much power engine is delivering. The more throttle the
longer the transmission will take to up shift and when down shifting the more throttle
the sooner the downshift. When I drove my Monaco when the King control was getting
repaired the trans would shift but not when it should.
Title: Re: Q about throttle position sensor
Post by: wolfe10 on July 12, 2022, 05:11:11 pm
No first hand experience with issues with TPS, but I would like to suggest two things:

Select economy mode for earlier upshifts/later downshifts.

Try up arrow to see if that will cause a shift at a more appropriate/lower RPM.
Title: Re: Q about throttle position sensor
Post by: Bob & Sue on July 12, 2022, 05:44:30 pm
We recently had trouble with our TPS ( bolt at injector pump wore thru ).  The Allison did not like shifting beyond 4th gear in regular mode but would shift semi-normal  with the mode button activated.

  And..  trans retarder would not work via the joystick.  New bolt and back to normal. 
Title: Re: Q about throttle position sensor
Post by: Dan & Annie on July 12, 2022, 05:55:46 pm
From what I understand without tps up shifts happen at max rpm, like 2600 to get into 6th. Also have heard down shifts can be hard.
This is exactly what I experienced yesterday when I took the coach out for its first test drive after replacing the King Controls unit with an air throttle and a new TPS from Alison. Wouldn't upshift until it reached something above 2,200 rpm, and stayed high when cruising at steady 40 mph. I think I need to either adjust the at-rest (idle) tension on the TPS cable where it attaches to the throttle lever, or re-attempt the calibration sequence (cycle ignition on/off six times, then press accelerator all the way with ignition on). Hoping one of these makes a difference.
Title: Re: Q about throttle position sensor
Post by: Realmccoy on July 12, 2022, 09:25:54 pm
One of the forum members had his Bendix go out and set up a hand throttle. He said it shifted at max rpm without tps. He was at Q last winter and installed air throttle and tps. Had a mechanic in Yuma help set up tps.