Bucking/Surging Epidemic

[Tim Vogt Sr.]

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.

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[Porpoise Hork]

Have not noticed this with mine prior to or after it was tuned.


Based on what you're stating it sounds like it's lugging from being in too high a gear for that speed or the transmission is hunting for the correct gear to be in. Press the +/- button on the gear selector to display the current gear the truck is in and observe its behavior to see if it's hunting gears.

Does the truck have factory towing? If so does it still do this when you enable tow mode? How about using the +/- button to lock out the specific gear it's in when at that speed raising the engine rpm. Putting it into S mode will do about the same thing.

Another possible thing but less likely is the transmission shift tables are all jackered up from there being multiple different drivers and the adaptive learning system not being able to properly adjust or towing when not in tow mode. This could potentially cause the transmission to hunt for gears and cause the bucking as described. Clearing the shift tables and have one person drive it around for 2-300 miles may help as well.

Have the dealer check the transmission fluid level. It's well documented on the Mustang, F150, as well as here (all use the same transmission) that Ford has been underfilling the 10r80 transmission at the factory by as much as 2+qts. This could also cause odd and random shifting issues.

 

[Tim Vogt Sr.]

Have not noticed this with mine prior to or after it was tuned.


Based on what you're stating it sounds like it's lugging from being in too high a gear for that speed or the transmission is hunting for the correct gear to be in. Press the +/- button on the gear selector to display the current gear the truck is in and observe its behavior to see if it's hunting gears.

Does the truck have factory towing? If so does it still do this when you enable tow mode? How about using the +/- button to lock out the specific gear it's in when at that speed raising the engine rpm. Putting it into S mode will do about the same thing.

Another possible thing but less likely is the transmission shift tables are all jackered up from there being multiple different drivers and the adaptive learning system not being able to properly adjust or towing when not in tow mode. This could potentially cause the transmission to hunt for gears and cause the bucking as described. Clearing the shift tables and have one person drive it around for 2-300 miles may help as well.

Have the dealer check the transmission fluid level. It's well documented on the Mustang, F150, as well as here (all use the same transmission) that Ford has been underfilling the 10r80 transmission at the factory by as much as 2+qts. This could also cause odd and random shifting issues.

1. Not lugging, though it feels kind of like lugging would just before the engine stalls. Problem occurs when truck is neither accelerating or decelerating. The moment you step on the gas, the problem is gone.
2. Tow mode made a negligible difference.
3. I am the only driver of this vehicle and in no way will I accept this has anything to do with adaptive learning. I can accept some hard shifts after the trans is reset, but not what mine is doing. It bucks to the point where eventually I am afraid it will damage something in the drive train. After 700+ miles after the last reset, driving it consistently, the problem has only worsened.
4. I asked if the tech checked the trans fluid level, but can't be certain they did at first. Hard to believe (but not impossible) that one of them hasn't checked it by now.
5. Mine shifts reasonably well and is not changing gears when the problem occurs, or at least the display does not show a gear change.

 

[Doak Steezy]

Having the same issue here it sounds like. I'm going to try a few fixes and see what happens (using tow or sport mode when I notice it happening) to see if it affects it at all. I have a pretty solid warranty and bought mine from a large-ish dealer where I am. If it doesn't go away or gets worse I will be taking mine in and I'll definitely be sure to update you if they find anything.

Does yours almost feels like a brief misfire when it happens also? That's one of the only ways to describe it other than jerking/bucking or slipping, but it happens in gear

 

[Porpoise Hork]

1. Not lugging, though it feels kind of like lugging would just before the engine stalls. Problem occurs when truck is neither accelerating or decelerating. The moment you step on the gas, the problem is gone.
2. Tow mode made a negligible difference.
3. I am the only driver of this vehicle and in no way will I accept this has anything to do with adaptive learning. I can accept some hard shifts after the trans is reset, but not what mine is doing. It bucks to the point where eventually I am afraid it will damage something in the drive train. After 700+ miles after the last reset, driving it consistently, the problem has only worsened.
4. I asked if the tech checked the trans fluid level, but can't be certain they did at first. Hard to believe (but not impossible) that one of them hasn't checked it by now.
5. Mine shifts reasonably well and is not changing gears when the problem occurs, or at least the display does not show a gear change.

Hmm...

Any noticeable change in RPM?? How about using a third party scanner app like Torque (Android)? You can use it to see what the throttle body plate angle is doing when it starts this. Possible that the throttle body plate is opening/closing rapidly. If it is it could be a faulty throttle position sensor or throttle body. May also look at the fuel pressure reporting after the HPFP (high pressure fuel pump) and make sure it's stable and not fluctuating to much.

 

[Ranger8729]

Not sure if our trucks have them, but I had the exact issue on two of my Jeeps ('01 and '06). The Throttle Position Sensor (TPS) had a dead spot, and the ECU just didn't know what to do.

 

[Tim Vogt Sr.]

Hmm...

Any noticeable change in RPM?? How about using a third party scanner app like Torque (Android)? You can use it to see what the throttle body plate angle is doing when it starts this. Possible that the throttle body plate is opening/closing rapidly. If it is it could be a faulty throttle position sensor or throttle body. May also look at the fuel pressure reporting after the HPFP (high pressure fuel pump) and make sure it's stable and not fluctuating to much.

No noticeable change in RPMs that I can remember. Would an engine issue like these cause the ECM or PCM (?) to throw a code?

 

[Porpoise Hork]

Not sure if our trucks have them, but I had the exact issue on two of my Jeeps ('01 and '06). The Throttle Position Sensor (TPS) had a dead spot, and the ECU just didn't know what to do.

It does.

Pedal Travel Sensor - Ford (AB3Z-9F836-B)

No noticeable change in RPMs that I can remember. Would an engine issue like these cause the ECM or PCM (?) to throw a code?

Not necessarily. It will usually trip a code if the sensors fail to report back or are outside the programmed tolerance for that particular sensor. If one is giving inconsistent readings the ECM may not log it as a code. You or a tech would need to monitor the voltage output from the applicable sensors with a scan tool to verify that say the throttle position sensor voltage is reporting correctly across the entire pedal travel as well as the throttle body angle is staying consistent in relation to the throttle position. Fuel pressure issues are along the same lines, it may trip a code if the system detects the problem, but these usually result in the ECM also going into limp home mode.

Coilpack mis-fires can also cause this sort of thing, but these will typically cause at the very least a soft CEL if they are severe enough to cause the reported drivability problems you're having. The CEL will stay on until the issue is no longer detected and/or a set number of key cycles (usually 3-5) has been completed and the mis-fire is no longer present. Some systems will log the mis-fire even if the CEL shuts off or never illuminates in the first place.

 

[wanted33]

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

 

[Jerry Caldwell]

Mine has started doing this as well. Doesn’t seem to happen when in cruise, but definitely when I feather the throttle. It threw a power train fault with the orange wrench a couple of days ago and at that point I returned the tune to stock to see if it does it again before taking it to the dealer. And yes, it immediately went in to limp mode.

 

[FoD]

It does.

Pedal Travel Sensor - Ford (AB3Z-9F836-B)



Not necessarily. It will usually trip a code if the sensors fail to report back or are outside the programmed tolerance for that particular sensor. If one is giving inconsistent readings the ECM may not log it as a code. You or a tech would need to monitor the voltage output from the applicable sensors with a scan tool to verify that say the throttle position sensor voltage is reporting correctly across the entire pedal travel as well as the throttle body angle is staying consistent in relation to the throttle position. Fuel pressure issues are along the same lines, it may trip a code if the system detects the problem, but these usually result in the ECM also going into limp home mode.

Coilpack mis-fires can also cause this sort of thing, but these will typically cause at the very least a soft CEL if they are severe enough to cause the reported drivability problems you're having. The CEL will stay on until the issue is no longer detected and/or a set number of key cycles (usually 3-5) has been completed and the mis-fire is no longer present. Some systems will log the mis-fire even if the CEL shuts off or never illuminates in the first place.

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)?

 

[Trigganometry]

Some on here have had water get into the spark plug wells. The ceramic cracked or corrosion to the spark pack spring. Seating of the spark pack has also been an issue for some. Easy to check and fix.

 

[D Fresh]

I think you guys are on the right track now.

I've never had this happen or even seen other threads about it.

But it sounds like a fueling or spark issue to me. Not sure why the transmission would be suspected.

Unless they're thinking it's slipping in and of of gear, which seems unlikely.

 

[Jerry Caldwell]

Some on here have had water get into the spark plug wells. The ceramic cracked or corrosion to the spark pack spring. Seating of the spark pack has also been an issue for some. Easy to check and fix.

Water in the spark plug wells should be incredibly rare unless they are washing the engine down on a regular basis. A random miss that this might cause would trigger a "Check Engine" code, not a drive train failure event with the little orange wrench.

 

[MNTBREW]

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.

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