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2018 10R80 Tow/Haul Engine Braking Downshift Causing Acceleration

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2018 10R80 Tow/Haul Engine Braking Downshift Causing Acceleration

Old 05-16-2018, 05:05 PM
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Default 2018 10R80 Tow/Haul Engine Braking Downshift Causing Acceleration

I have a 2018 Screw 3.5 Max Tow, when in Tow Haul mode down a hill, the transmission will shift from 4-3 and 3-2 under braking (as expected). About 5-10% of the time, when the transmission does this, the torque converter remains locked and the engine tries to "rev match" the speed of the engine to the next lowest gear ( I assume for comfort and reduced stress on drive train). When it does this, the truck actually accelerates 5-10 MPH because the tq converter is locked and the truck is in a gear. The first time this happened on a curve towing a trailer was a shock, downright scary. Anyone else experienced this? Is there a PCM/TCM update available?

The dealer wanted to keep the truck for a day to inspect, but I know they won't be able to recreate. I don't want them to have it for a day I just want my VIN checked to see if there is an update in OASIS. Anyone able to run a VIN and check for updates?

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Old 05-16-2018, 05:10 PM
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I have not experienced what you speak of, but I tow a 7500 lbs travel trailer with my 18, I also towed it with my 16. My 18 has the 3.5EB, my 16 had the 5.0, as expected, engine braking was MUCH better with the v8, and is basically non-existent on the ecoboost.
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Old 05-16-2018, 05:15 PM
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Mine (2018 SCREW 3.5 HDPP) does this too in T/H mode, especially 3-2 on steep downhills, off the gas, when towing my light (2000lb) enclosed trailer. First time it caught me by surprise on a steep curvy road. Now I'm ready for it.

I haven't noticed it with my 8000lb toy hauler, but I don't tow that as much.

I've heard of no TCM updates, and haven't mentioned it to my dealer. Mine also makes the knock at startup. Not a perfect truck for sure.

Mike
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Old 05-16-2018, 06:14 PM
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Originally Posted by mhamershock View Post
Mine (2018 SCREW 3.5 HDPP) does this too in T/H mode, especially 3-2 on steep downhills, off the gas, when towing my light (2000lb) enclosed trailer. First time it caught me by surprise on a steep curvy road. Now I'm ready for it.

I haven't noticed it with my 8000lb toy hauler, but I don't tow that as much.

I've heard of no TCM updates, and haven't mentioned it to my dealer. Mine also makes the knock at startup. Not a perfect truck for sure.

Mike
My truck has done this a few times on the 3-2 downshift when not towing when manually downshifting in regular mode. It has not done it in T/H mode while towing and letting the transmission pick it's own gears or downshifting manually, doesn't mean it wont. It's never done it on anything but the 3-2 downshift. I've never picked up 10mph, maybe 2-3 mph because it then goes to neutral before hitting the next gear.

I think this is an issue with the a clutch pack not releasing fast enough. I think the torque converter is supposed to stay locked, the first clutch releases, it rev matches and then another clutch engages the next lower gear.

This isn't really an automatic transmission in the traditional sense. It's more an electronically controlled manual transmission with an overriding torque converter.

I'm guessing you need 5,000 RPM with the 3.5EB to get the engine braking of a 5.0 at 3,500 RPM. The little guy needs an exhaust brake IMO.
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Old 05-16-2018, 06:20 PM
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It does feel like a rev match gone a bit wild. My 2017 Q50s rev matches downshifts in manual mode quite well. This is the TCM controlled version of that, and it's not well programmed. Gaining a few MPH in certain situations when towing is not ok.
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Old 05-16-2018, 06:24 PM
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Originally Posted by mhamershock View Post
It does feel like a rev match gone a bit wild. My 2017 Q50s rev matches downshifts in manual mode quite well. This is the TCM controlled version of that, and it's not well programmed. Gaining a few MPH in certain situations when towing is not ok.
Hopefully Ford comes up with a programing fix soon!
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Old 05-16-2018, 06:30 PM
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I've also experienced this manually locking out gears, without a trailer (and not in tow/haul) mode. The local ski area is about 2,000 feet above town, mostly gained over the last four or five miles of driving to get there. On the way back down, I can generally keep the speed where I want it by dropping gears on the 10-speed, but every so often shifting 3-2 in particular seems to create acceleration rather than deceleration.
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Old 05-16-2018, 06:32 PM
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Does ford have a recall hotline... This sounds like a candidate!
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Old 05-16-2018, 07:11 PM
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How heavy is the OP's trailer? Tow haul works best with heavy loads, 50% or greater of max trailer weight for your truck. With light trailers tow haul is more of a nuisance than a help but with 5,000 lbs pushing you it's appreciated.
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Old 05-16-2018, 07:49 PM
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Originally Posted by kbroderick View Post
I've also experienced this manually locking out gears, without a trailer (and not in tow/haul) mode. The local ski area is about 2,000 feet above town, mostly gained over the last four or five miles of driving to get there. On the way back down, I can generally keep the speed where I want it by dropping gears on the 10-speed, but every so often shifting 3-2 in particular seems to create acceleration rather than deceleration.
Exactly what I have experienced, downshifting 3 to 2, but very temporary. Haven’t noticed it towing or in tow mode. (‘17 3.5EB). Not 5-10mph, but enough to be get one’s attention approaching a curve!

Last edited by BadAltitude; 05-16-2018 at 07:54 PM.
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