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Thread: 2008 A40 downshifting with cruise control

  1. #1
    Lifetime Member minytrker's Avatar
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    Default 2008 A40 downshifting with cruise control

    Are there tables we dont have access to for shift points on cruise control? With cruise control off I have it my downshifting dialed in exactly where I want it. With cruise control on it downshifts into 5th back into 6th a lot where I have my tune with cruise off stay in 6th. Im only towing 10k or less.

  2. #2
    Lifetime Member killerbee's Avatar
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    Quote Originally Posted by minytrker View Post
    Are there tables we dont have access to for shift points on cruise control? With cruise control off I have it my downshifting dialed in exactly where I want it. With cruise control on it downshifts into 5th back into 6th a lot where I have my tune with cruise off stay in 6th. Im only towing 10k or less.
    No, the tables are no different. It's your cruise control process controls equation. Look at your shift tables, they are all TPS signal dependent. CC liberally uses up to all your throttle to maintain the speed set point. The human input usually doesn't. That is what is causing your hunting, and the exact same thing would happen if you tried to maintain that setpoint with your foot.

    Your best bet to reduce hunting with CC, is OD off.
    Michael, Systems Engineer 04.5 D-max LLY, Phoenix, Arizona Email
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  3. #3
    Lifetime Member minytrker's Avatar
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    I was just making sure there wernt separate tables that I couldnt see. I can maintain 70mph with my foot and it wont downshift. Same road, same trailer 70mph cruise control will downshift. I have noticed though that cruise control gives it more throttle faster which IMO is causing the downshift. I towed 100 miles on back roads this week at 65mph in 5th and it very rarely downshifted. When I went there on a different road going 70mph it shifted out 6th on every hill with cruise on. I'll have to do some more logging, and try leaving it in 5th and se how it does.

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