Turbo boost oscillations while towing

[Fishstxy]

When towing a 5,000lb trailer in both normal and tow/haul mode, at low RPM with mid boost demand ( low throttle demand) the boost pressure will start to oscillate violently. I assume this is the waste gate flapping. I can break the condition by either adding or removing throttle input.

I noticed it originally by the strange chirping should from the engine. When I switched to the boost gauge view (Lariat dash) I could see the boost pressure oscillating at about 3 times a second. Seems to consistently kick in cruising at highway speeds at constant power

Anyone else seen this? It can’t be good for the turbos so I’m tuned in to try to avoid it.

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[superfordman]

My truck will do the exact same thing at just the right times, sometimes towing or not. Seems to depend really on the conditions, load (head wind for me usually), speed and throttle. Just like you said the BOV starts fluttering back and forth and so do the boost gauge slightly, then just a simple tap of the throttle and goes away. No idea why it does it, but has since day one and have almost 66K right now and no issues, so I don't worry about it too much. It really seems to do it more when I have my big wheels and tires on, more load essentially.

 

[TheGoatman]

Octane?

 

[Fishstxy]

Octane?

93

 

[TheGoatman]

Do you go wide open throttle every so often?

if it’s a 21, an ecm update at the dealer may help too

 

[DT400]

When your boost is pulsing have you noticed the rpm's bouncing in rhythm? Mine does this but it has been attributed to a bad torque converter (locking/unlocking) unfortunately they are on back order and no deliver time is even estimated.

Darrell

 

[Gros Ventre]

The symptoms, I believe, point directly at a flaw in the computer coding.

 

[GIjoe]

I’ve noticed my mpg’s doing the same thing. I’ll have to pay more attention to my turbo gauge and see if it’s related

 

[Fishstxy]

Do you go wide open throttle every so often?

if it’s a 21, an ecm update at the dealer may help too

Rarely. I can try this next time I'm towing. I have experimented with WOT unloaded in Sport mode a few times, but that's it.

 

[Fishstxy]

When your boost is pulsing have you noticed the rpm's bouncing in rhythm? Mine does this but it has been attributed to a bad torque converter (locking/unlocking) unfortunately they are on back order and no deliver time is even estimated.

Darrell

No change in RPM, just chirping from the turbo which sounds like waste gate flapping. I noticed it happened a lot less with cruise control on, but not 100%.

I'll try to get a CarScan data record next time.

 

[TheGoatman]

If you catch it early enough a fluid change may help. I am planning on doing a fluid change at the dealer at 20k miles. Using the ford pass points I got at delivery

 

[RuggedGoods]

Just a weak spot in the engine calibration, basically. The control loop for requested/actual boost isn't very sophisticated.

Easy way to solve it is probably to avoid low rpm when towing (lock out your high gears). Or get a Livernois tune.

 

[powerbeast]

I noticed mine would oscillate engine output during low rpm high load when running low Octane, which was further exacerbated during the summer temps. Almost like timing was being retarded. 91Octane solved this issue.

 

[GIjoe]

Just noticed this today going uphill with low rpm and moderate throttle. Sounded like a belt slipping at first but I could make it worse/louder with more throttle. Forced a downshift and went away.

 

[pbensen]

Hello all,



I have a 2022 F150 Lariat with the 3.5 Eco-boost non-hybrid. It is equipped with the max tow package (14k lb.). I have the exact problem; turbo boost flutter/oscillations at cruise towing my 6500# travel trailer (65-70mph, 1800-1700 RPM, 9th gear, 5-10psi boost). I also notice that the engine speed fluctuates 100 RPM when the boost is fluctuating. This definitely concerns me; maybe the torque convertor is unlocking and locking along with the boost being blown off then snapped back up quickly and constantly. I have taken it to two different dealerships to have the problem diagnosed and resolved. The first dealership said "so sorry, no trouble codes, not a problem, have a nice day". The second dealership used the TSB 23-2353 to flash a new calibration in the PCM. They did a road test and said they found that the RH wastegate would not stay steady at WOT. They replaced the wastegate and thought all it good.



I picked up the truck, went home, connected up the trailer and took it for a test drive. I noticed that the truck seems to have more power; quicker boost ramps up, high boost pressure than before. That was fantastic, the only problem is that when I tow at a level 65MPH cruise the boost flutters continually (7-9psi) and the RPM moves from 1700-1800 RPM. Before the PCM flash I could move the accelerator a little bit and the flutter would go away. This is more concerning than ever as this is the exact target speed I pull at. I went back to the dealership and spoke with the service advisor and told him what was happening. He told me that there is nothing else that they can do as there are no trouble codes present and no TSB’s in the system to fix the problem. He said that I would have to take it to another Ford dealer to get a second opinion before Ford Service Division would send out an engineer. I thanked him for his time for the other issues with the vehicle that were addressed and resolved. One of these was a failing AGM battery. They replaced it, finally; I was getting a constant reminder on the Ford app that the truck was going into deep sleep mode because the battery was low.



I called the Ford Customer service hotline today. I explained the problem to them accurately and succinctly. I told her that I am a retired Ford Motor Company engineer with powertrain calibration experience. and that I believe that this is a powertrain calibration issue I agree with Gros Ventre above. The lady told me that I would have to take it to another dealership and get a second opinion/diagnosis. She said that if I can get the dealership tech to verify the issue with data and there is no fix available, they would send out a field service engineer to the dealership to work with the tech. She said that at that time I could pursue getting my truck swapped out for a new one. I told her that I custom ordered my truck, I love everything about it and that I want to get this problem resolved. I would imagine her eyes were rolling at this point :O|



The problem now with that it is winter here in Canton, Michigan. I don't drive my truck in the winter (nasty, salty roads). I also don't pull my travel trailer in the winter. I so wish that Ford could and would take the truck to Dearborn, put it on a dyno and verify the problem. I'm going to have to convince another Ford dealership to have one of their techs rides with me while towing my trailer with the IDS connected recording all the pertinent data. The dealership techs don't want to do that because they are not guaranteed to get paid because there are no codes in the computer.



The good news is I have some time, my truck is still under the 3yrs 36K mile bumper to bumper warranty. The truck has 35,500 miles on it now. The time is up at the end of April 21st, 2025. I am not currently driving it (put away for the winter). I usually put the truck back on the road in May.



I plan to go in person to another Ford dealer in the area and explain my problem to see if they will work with me to get the powertrain data and get Ford Service Engineering involved. I'll let you all know how it is going. With some perseverance and a little luck, I hope to get Ford to verify the concern, develop and release a new calibration to resolve this issue. I can only imagine how many millions of customers with F150's with the 3.5 Eco-boost engine towing trailers are having this same problem. I could only imagine how many turbochargers, turbocharger wastegate actuators, boost blow off valves and transmission torque convertors and being adversely affected.



One would think that Ford Motor Company would want to get this turbo boost oscillation/flutter problem identified and resolved ASAP. Think of the warranty costs! I wonder if this is still an issue with the new 2025 F150's currently being built and sold? From the information that I have seen in internet posts, this issue has been happing with past generations of F150 tucks with 3.5L Eco-boost engine.

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