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Discussion Starter · #1 ·
Hi - I have learned a lot from you folks and I hope someone can help me understand what my truck is doing. My truck does not coast. It always seems like the transmission is braking. Not a lot but when I let off the gas there is a noticeabIe drag. I have had the truck a year and have put about 15K miles on it for a total of 42K. I have not had it in the shop for this. Also, if I am driving and I put the tranny in neutral the RPMs do not drop to idle, they stay up where the engine was running in gear. I drive a Ford 1 ton dually at work and when I left off the gas in that thing thee engine goes into idle and you can feel the truck coast easily. I know this has to be affecting my mileage. I have to give it gas go down fairly steep hills. I get about 14 mpg now. Any ideas or comments will be appreciated.
 

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I've heard opening up the exhaust let's them coast a lot better. Especially on DPF trucks. I am curious as to whether this is true bc my truck loses speed when it should gain it trying to coast. Cat needs to go I think...
 

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I think it has something to do with the traction control/stabilitrak system. & opening up the exhaust (DPF remove) would help it coast. I get 15-17mpg in town.
 

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Ya i am kinda of curious about this too. My truck does the same. I do not have the delete but there is a muffler on it. Although i do notice my rpms do go to idle when i go to neutral and i can tell it coast a lot better but its a pain to drop to neutral all the time. If anyone has an answer i would love to know.
 

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Sounds to me more like the transmission is staying in Tow/haul. It has nothing to do with the exhaust. Not everything in the world can be cured by a delete, and a programer.
You may have to take it somewhere that can do a scan, a Dealer or a transmission shop to know for sure.
 

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sounds to me more like the transmission is staying in tow/haul. It has nothing to do with the exhaust. Not everything in the world can be cured by a delete, and a programer.
You may have to take it somewhere that can do a scan, a dealer or a transmission shop to know for sure.
x2..
 

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my dealer sucks so im not taking it there... not to many tranny shops near me.
 

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anyone know what might have caused this? or does this sound like a common thing?
 

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The Allison is designed that way from my understanding, unless you set cruise control, "coasting" is not allowed by the tranny. I drive an 02 and its the same way for me, even going down a hill it will slow down. Youll notice even when in cruise control going down a hill, you can feel the truck pull to gain speed and the tranny will not let it (hence the no rpm drop). Just my experience and what Ive gotten from reading. Maybe someone like Mike L can post about it
 

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Discussion Starter · #10 ·
Thanks to you all who are replying. I am surprised that anyone knew what I was talking about and really surprised to see it seems to be the standard (?). Bigblackdiesel - you sound like you have heard of this before. I will be disappointed if there is no way to proceed down the road without my foot in the fuel!!
 

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Yeah man it seems unfortunate, but im sure there is some method to the madness. Like I said, cruise control is your best bet for now.
 

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My LMM weighs 11k and it does not have a problem coasting... But it probably has alot to do with the extra 3k. My Rpms do not drop when I let off the gas either.
I think it is just the nature of the truck. The truck also has a computer that tells it when it is safe to drop in or out of gear.
 

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for me its usually at slower speeds around 35ish mph....
 

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Make sure you let off the accelerator completely, a lock up torque convertor will stay locked and not free wheel if there is any throttle applied at all. These trucks have an electric throttle so there is also a delay in response to throttle position to deal with as well. It seems to be the nature of the beast and will drive you up a wall trying to change it so just learn to live with it
 

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So your saying the torque converter could be the problem? Now could there be something wrong with the torque converter or even the accelerator that could be causing this? Could the accelerator be not coming up all the off giving it a little throttle?

How exactly does the torque converter work?
 

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now time for the really dumb question... How/Who can do the TCM tune?
 

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I will be disappointed if there is no way to proceed down the road without my foot in the fuel!!
mine has 85k miles on it and i have not had to change the brakes yet still stops like the day i bought it ill gladly push the skinny pedal down the hill and not replace my brakes
 
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