6.7L powerstroke transmission jerking under a load?
Thread Starter
|
Fleet Mechanic
Joined: Nov 2019
Posts: 1,429
Likes: 487
From: North Carolina
6.7L powerstroke transmission jerking under a load?
I bought an 18' f250 and have 28k on it now. When I tow my gooseneck trailer and I merge on the highway going up a roughly 4% grade onramp my truck likes to torque. As I take off easy in tow haul and let the truck do its thing. The rpms seem to be around 1500ish if I recall, but the transmission feels like it's slipping. It jerks the entire truck, like the motor has a miss in it. Is this normal? It doesn't always do it it's done it about a dozen times, and its always at low rpms 3rd to 2nd gear downshift. This time it was the worse its ever been! I gave it more gas and it did it worse till it downshifted. Just wondering if it's normal and if anyone else has had this happen.
Tuned
Joined: Feb 2022
Posts: 284
Likes: 81
That doesn’t seem normal unless your boost is just building up while going from slow speed with no boost to heavy throttle input and you’re accelerating pretty hard when it’s happening but doesn’t sound normal for light constant throttle input
Thread Starter
|
Fleet Mechanic
Joined: Nov 2019
Posts: 1,429
Likes: 487
From: North Carolina
Its basically feels like the truck will not downshift, instead it keeps using its torque to hold the gear. Then its like it gets to the point its about to stall the motor, so it starts riding the torque converter to keep it from happening. I them push the accelerator down to the floor amd it only gets worse with symptoms of really bumpy or like a gasser firing on 5-6 of the 8 cylinders. Then if will finally downshift. I did see online people installing aftermarket solenoid with increased line pressure, I dont know if that's why people were doing it. Not that big of a deal, I can live with it, I just feel it's not good on it, as my dads 2016 doesnt do that.
Tuned
Joined: Feb 2022
Posts: 284
Likes: 81
Its basically feels like the truck will not downshift, instead it keeps using its torque to hold the gear. Then its like it gets to the point its about to stall the motor, so it starts riding the torque converter to keep it from happening. I them push the accelerator down to the floor amd it only gets worse with symptoms of really bumpy or like a gasser firing on 5-6 of the 8 cylinders. Then if will finally downshift. I did see online people installing aftermarket solenoid with increased line pressure, I dont know if that's why people were doing it. Not that big of a deal, I can live with it, I just feel it's not good on it, as my dads 2016 doesnt do that.
Tuned
Joined: Feb 2022
Posts: 284
Likes: 81
I don’t feel like a Diesel engine should be lugging around at 1500 rpm. It will need to build boost to feel like it has more power at low rpms then when the boost hits it almost feels like a clutch slipping in a way.
It almost sounds more like a software or tuning issue that your boost isn’t building fast enough or the transmission had learned to shift in spots that don’t make sense for your driving somehow since it goes away when you downshift when you put the transmission in the manual setting.
I think there’s a way to reset the software so the transmission learns new shift points based on your driving style. I’m sure there’s a way to look it up. I haven’t don’t it on mine since I bought it new.
Take all that with a grain of salt, I’m no mechanic or engineer by any means.
It almost sounds more like a software or tuning issue that your boost isn’t building fast enough or the transmission had learned to shift in spots that don’t make sense for your driving somehow since it goes away when you downshift when you put the transmission in the manual setting.
I think there’s a way to reset the software so the transmission learns new shift points based on your driving style. I’m sure there’s a way to look it up. I haven’t don’t it on mine since I bought it new.
Take all that with a grain of salt, I’m no mechanic or engineer by any means.
Thread Starter
|
Fleet Mechanic
Joined: Nov 2019
Posts: 1,429
Likes: 487
From: North Carolina
I asked the dealer about it. He said the reflash will not change a thing since it was just reflash when I bought it back in February. He said wait a couple more months becuase roughly every 6 months they update it. (Guy didnt seem real knowedgeable). But I will say the jerking happened again today on flat ground as I slowed down for a curve then slowly accelerated, after the curve. Seems to be gradually getting worse. Starting to think I got a bad one.
Trending Topics
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Thread Starter
|
Fleet Mechanic
Joined: Nov 2019
Posts: 1,429
Likes: 487
From: North Carolina
I've tried everything. Truck runs great but it does it in all gears now. But it doesnt always do it, its hit or miss. At 26k it started in 3rd gear, and it did it pretty hard. Felt like truck was running on 6 cylinders. I got 30200 miles on it now, and its gradually gotten worse. It does it in 5th gear and 4 gear as well. I dont tow in 6th. Truck runs great but when it does it its very violent. My seat shakes, truck does a hopping motion kinda thing. It feels like a gasser running on 6 cylinders with coil/spark plug failure. I look in my mirror and see my trailer shaking. I was thinking it was a program issue but I am starting to think it feels like the tc is slipping. Guess I need to not worry about it and just drive till it breaks. I guess nobody else has had the same issue. I will note, my dad 2016 f350 ccsb, does not do this.
Thread Starter
|
Fleet Mechanic
Joined: Nov 2019
Posts: 1,429
Likes: 487
From: North Carolina
Took to the dealer. He drove it solo and scanned the it. Came back and said it was fine.(I knew they would say that as it only does it when towing). I described to him what it was doing, and he said it sounds like something internal in the trans is bad/defective. The shop mechanic guy wants me to bring back with my 20k gooseneck flatbed and see if he can get it to start doing it. In the next week or so I will take it back by when I get a chance. They are 2 months out for tranny warranty work he did state. I'm just gonna continue to drive and it might stay the same or get worse, as I only tow 8-10 times a month max. Good news is I got the good ol trusty duramax to take its place if it breaks.
Cross-Country
Joined: Jan 2005
Posts: 62
Likes: 2
From: Red Bluff, CA
Hello Mr. Rice. I have a 2016 F350 that does the same thing that you described above. Mine usually does it under load at around 5000 feet and above altitude and temps above 90 degrees F. It jerks so much that my wife damn near has a heart attack. When I use M and manually shift gears I can get it to stop. I just came back from Mammoth Lakes and I had the same problems traveling there with a load. Back in 2019 I had the dealer change the transmission fluid at 69916 miles and check the pan for debris and they didn't find any. They did say that I was throwing a Code 17M04 and that they replaced the CCV Collar Kit and reset Code P04DB. "Replaced crankcase collar and reprogrammed PCM all good." I have no idea what the problem is and when I try to explain to the dealer they say is it throwing a code and do you have a video of it happening. I tell them that it is random and my wife can't get the video because I switched to M so I can get off the road. D.
1st Gear
Joined: Jun 2026
Posts: 1
Likes: 0
I know this thread is 4 years old, but did you ever find a solution for this issue? Mine is doing exactly what you guys describe. Bucks and jerks with a light load under light throttle and get worse the more throttle you apply. Downshift manually and it goes away. 2018 stock. 165k miles. Doesn't do it every time. Go into a hill aggressively under heavy throttle and it never misses a beat.
Thread Starter
|
Fleet Mechanic
Joined: Nov 2019
Posts: 1,429
Likes: 487
From: North Carolina
I know this thread is 4 years old, but did you ever find a solution for this issue? Mine is doing exactly what you guys describe. Bucks and jerks with a light load under light throttle and get worse the more throttle you apply. Downshift manually and it goes away. 2018 stock. 165k miles. Doesn't do it every time. Go into a hill aggressively under heavy throttle and it never misses a beat.
when I used it to haul heavy equipment till 40k miles. Gooseneck weighted 23k lbs. it would buck.
it is from line pressure not being enough with weight. The fix is a BD shift solinoid in the transmission to increase the line pressure. It will hit hard and not hesitate.
Anything 15k or less doesn ever really do it. He never says anything at least.
Lead Driver
Joined: Nov 2005
Posts: 5,227
Likes: 4,242
From: Kaysville Utah
I was having problems with my 2023 truck, It had awful jerking, Usually when it downshifted fro, 5th to 4th when I was towing up a 6-7% grade. I was usually around 45-50 mph when it happened
Dealer could not replicate, No error codes., They told me to drive it until it blew and they would work on it then
I took it into a local mechanic and he suggested the same thing I was finding on the internet. Change the fluid and filter. Which I had him do. No problems since.
My original probably was around 54,000 miles, I'm currently at 79,000
Dealer could not replicate, No error codes., They told me to drive it until it blew and they would work on it then
I took it into a local mechanic and he suggested the same thing I was finding on the internet. Change the fluid and filter. Which I had him do. No problems since.
My original probably was around 54,000 miles, I'm currently at 79,000
