Bucking/Surging Epidemic

[Tim Vogt Sr.]

From what the OP is describing it sounds like his problem is torque converter shudder. He didn’t say what the mileage was on his truck but I’ve seen this very same issue on fairly low mileage Honda’s with 5 and 6 speed autos and GMs with the 8L series automatic. It’s also described as driving over rumble strips.

It generally occurs at a crushing speed once the converter clutch is locked and your either not trying to accelerate or you apply the throttle very lightly. The cause is usually do to worn out transmission fluid that no longer has sufficient friction additives and therefore can’t keep the converter clutch from slipping (shuddering) during low rpm/higher load conditions.

The fix on the GM and Hondas is to perform a fluid exchange ,not a flush, and on some of the 8L series autos the converter clutch had also been damaged from the shuddering and needed to be replaced.

Also if it’s a 19 it may need the software update for the transmission applied yet as well.

Sounds exactly like what is happening with my truck.
My Ranger has around 23,000 miles on it. Had TSB 20-2339 done around 2 months ago which made no difference.

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[D Fresh]

It does sound like a fuel flow issue/gearing...not having done it, is it possible to manually set gearing while on cruise? re: see if gear drop makes any difference (ref prior comments on lugging)?

I'm pretty sure you can.

And I'm absolutely sure that at a minimum you can lock out gears and put the gear display up when using cruise.

 

[Zaph]

?Subbed for just in case as mine hasn't done this........yet.

Same here. I have a long section of road to work that is 35 mph speed limit so I set the cruise control to 40 and it's dead smooth.

But like @Ranger8729 said I would suspect the TPS also. I had a motorcycle with that issue once. Drove me crazy until I found it. Of course it was one of my street bikes, because wide F'n open at the track doesn't have that problem.

Edit: was was able to see the dead spot by hooking a computer up to the bike and reading the voltage with some special software. (TuneECU on a KTM) No idea how to do it in a truck though.

 

[MNTBREW]

If the transmission tech is unable to find anything else wrong with your truck you could suggest that he monitor the converter slip speed when the bucking/surging occurs. If the converter clutch is the issue you should see the slip speed rpms fluctuate by 100+ rpms and the converter clutch solenoid duty cycle will more than likely be upwards of 80% or higher because it’s trying to compensate for the erratic slip speed and bring it back down to low double digit rpms.

 

[VegasRanger]

I think mine is doing this! I thought it was a bad or out of round tire. Mine does it around 30-40. Does it feel like going over a washboard? Thought my rear tires were out of balance by discount tire said they were perfect. Maybe it is this issue.

 

[MNTBREW]

I think mine is doing this! I thought it was a bad or out of round tire. Mine does it around 30-40. Does it feel like going over a washboard? Thought my rear tires were out of balance by discount tire said they were perfect. Maybe it is this issue.

Torque converter shudder is also described as driving over a washboard so it’s very possible that is your issue.

 

[E Monty]

Same thing here, about 29K. Shudders at low RPM.

 

[Jerry Caldwell]

Same thing here, about 29K. Shudders at low RPM.

It definitely happens at low rpm when the trans probably shifts a little too early and the rpm is in the 1600 range.

 

[VegasRanger]

Torque converter shudder is also described as driving over a washboard so it’s very possible that is your issue.

Anyway to rule out the TC? Shifting into N while cruising at 30-40? If it still does it, would that rule out the TC?

 

[MNTBREW]

Anyway to rule out the TC? Shifting into N while cruising at 30-40? If it still does it, would that rule out the TC?

While the shudder is happening, lightly depress the brake pedal while keeping your other foot on the gas with the same amount of pressure that you used to cause the shudder to occur. If you notice the shudder stop and see the engine rpms increase then you know that the torque converter has unlocked and proved that the converter is the source of the problem.

However this method may or may not work on the 10 speed, it did with the older 4 speed autos but it doesn’t with the 6R series autos. Your other option is to use a scan tool that supports the function to disable the torque converter clutch. I use the Ford IDS factory scan tool at work so I know that supports that function but you may get lucky with some of the higher end universal scan tools.

What you don’t want to do is accelerate to hard that you cause the transmission to downshift or cause the converter clutch to unlock without you knowing because then you don’t know if the source of the problem is the torque converter clutch or one of the clutch assemblies in the transmission.

Also the farther the gas pedal is pressed the higher the transmission fluid pressure goes which can potentially compensate for any degradation in the transmission fluid, wrecking the test.

One other test you can try, if the scan tool your using supports it, is increase the torque converter clutch solenoid duty cycle which will increase the amount of fluid apply pressure to the converter clutch. If the shudder goes away then you know that the converter clutch can’t stay properly engaged at the computers’ designated duty cycle.

If that’s to long winded let me know and I’ll break it down better.

 

[VegasRanger]

While the shudder is happening, lightly depress the brake pedal while keeping your other foot on the gas with the same amount of pressure that you used to cause the shudder to occur. If you notice the shudder stop and see the engine rpms increase then you know that the torque converter has unlocked and proved that the converter is the source of the problem.

However this method may or may not work on the 10 speed, it did with the older 4 speed autos but it doesn’t with the 6R series autos. Your other option is to use a scan tool that supports the function to disable the torque converter clutch. I use the Ford IDS factory scan tool at work so I know that supports that function but you may get lucky with some of the higher end universal scan tools.

What you don’t want to do is accelerate to hard that you cause the transmission to downshift or cause the converter clutch to unlock without you knowing because then you don’t know if the source of the problem is the torque converter clutch or one of the clutch assemblies in the transmission.

Also the farther the gas pedal is pressed the higher the transmission fluid pressure goes which can potentially compensate for any degradation in the transmission fluid, wrecking the test.

One other test you can try, if the scan tool your using supports it, is increase the torque converter clutch solenoid duty cycle which will increase the amount of fluid apply pressure to the converter clutch. If the shudder goes away then you know that the converter clutch can’t stay properly engaged at the computers’ designated duty cycle.

If that’s to long winded let me know and I’ll break it down better.

Thank you

 

[Mitch65]

Mine sounds a bit different than what you describe but I just created a thread about this yesterday. When the truck is at low rpm and you feather the throttle you get a nasty feeling. Vibration, shutter, resonance ect. What ever you want to call it. Happens between 25-40mph on mine.

it’s tough because people describe things differently. My “vibration” may be someone else’s “shutter” lol

 

[wanted33]

From what the OP is describing it sounds like his problem is torque converter shudder. He didn’t say what the mileage was on his truck but I’ve seen this very same issue on fairly low mileage Honda’s with 5 and 6 speed autos and GMs with the 8L series automatic. It’s also described as driving over rumble strips.

It generally occurs at a crushing speed once the converter clutch is locked and your either not trying to accelerate or you apply the throttle very lightly. The cause is usually do to worn out transmission fluid that no longer has sufficient friction additives and therefore can’t keep the converter clutch from slipping (shuddering) during low rpm/higher load conditions.

The fix on the GM and Hondas is to perform a fluid exchange ,not a flush, and on some of the 8L series autos the converter clutch had also been damaged from the shuddering and needed to be replaced.

Also if it’s a 19 it may need the software update for the transmission applied yet as well.

Good point Jason. I had a '97 F-150 that required a tranny fluid change approx. every 10K miles. The torque would start doing the same thing.

 

[Apples]

Interesting data here:

https://gearsmagazine.com/magazine/the-more-you-know-about-the-10r80-the-better-off-you-are/

 

[Gerder]

Haven't checked in here in a couple of weeks and now see a bunch of threads discussing what I believe to be the same defect in various forms. "Bucking" is a good word to describe what my 2019 Ranger started to do a couple of months ago, or maybe longer than that. It started out barely noticeable and grew steadily worse until I wasn't sure I should be driving it.

I own a small HVAC business and buy a couple of trucks each year- vans and pick-ups. Our local dealer has a commercial Fleet sales department which is very friendly to me. After I threatened to not buy any more Fords, the commercial sales manager got involved. Two weeks later (this Wednesday), I get a call telling me that they now have four Rangers doing the same thing and they are not sure what to do to fix the problem. This not a large dealership. No codes are displayed and no TSBs fix it. Their lead tech is experimenting with the transmission software parameters to try to resolve the problem.

Here is how I can show the problem: drive 30-50 MPH on a smooth level road. Set the cruise or hold the accelerator in a neutral position to try to maintain a steady speed. Truck starts to buck very noticeably every time.

Please post up the fix if anyone's dealer has figured this out. Doesn't sound like Ford is ready to admit there is a problem or knows how to fix this. Hopefully it will be simple to correct.

kick ass of those machines from time to time works good as a miracle for me.
ok, mine is a diesel, but even gasoline cars need to be reminded what they are build for ??

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