Undesirable downshift, 4r70w when towing
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Undesirable downshift, 4r70w when towing
Towing with a '02 F-150 SuperCrew, FX4, 5.4L with a 4r70w that is over eager to hunt gears.
Running 70 MPH in OD, the engine turns about 1700 RPM. There is ample power for pulling the load, but the transmission won't hold a gear beyond a particular percentage application of throttle. With OD defeated, the engine turns 2800 RPM at the same speed. As a result, either the tranny through too much shifting, or the engine through excessive revs, gets flogged while towing. Then too, there's the negative effects on fuel consumption when running higher RPMs.
It would be of great benefit to prevent gear hunting when towing and it seems modification of the computer parameters that control downshifting might accomplish this objective. Maybe an 'auto-manual' type setup would be the solution.
Is there a product available to allow greater driver control over whether or when the transmission will downshift? How about something that would prevent torque converter lockup while towing?
Thanks,
Scott
Running 70 MPH in OD, the engine turns about 1700 RPM. There is ample power for pulling the load, but the transmission won't hold a gear beyond a particular percentage application of throttle. With OD defeated, the engine turns 2800 RPM at the same speed. As a result, either the tranny through too much shifting, or the engine through excessive revs, gets flogged while towing. Then too, there's the negative effects on fuel consumption when running higher RPMs.
It would be of great benefit to prevent gear hunting when towing and it seems modification of the computer parameters that control downshifting might accomplish this objective. Maybe an 'auto-manual' type setup would be the solution.
Is there a product available to allow greater driver control over whether or when the transmission will downshift? How about something that would prevent torque converter lockup while towing?
Thanks,
Scott
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Joined: Mar 2002
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From: Willamette Valley, Oregon
first of all, Welcome to FTE!!!
second, towing in OD is really not recommended, check your owners manual. what are the specs of your truck ie, tires, gears, weight of towing, conditions of road and weather and etc.
third, this sounds like a normal condition.
second, towing in OD is really not recommended, check your owners manual. what are the specs of your truck ie, tires, gears, weight of towing, conditions of road and weather and etc.
third, this sounds like a normal condition.
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Originally Posted by Ponyracer
towing in OD is really not recommended, check your owners manual.
Posting Guru
Joined: Mar 2002
Posts: 1,942
Likes: 3
From: Willamette Valley, Oregon
well there is your answer then. if it is shifting in and out frequently then dont tow in OD right? Right, so then as a former Ford Master Transmission and Drivetrain Technician, we dont recommend towing in OD for those reasons. enough said! Not to mention that this guys rig has a car like transmission(4R70W) and he needs to think about saving it for the long run.
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