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Discussion Starter #1
I am hoping that you all can help me shine a little light on an issue I am having before the truck goes to the dealership for service on the 19th.

When I go down hills and let off the gas, my boost gauge goes up to 5-7 psi, and you can physically feel the truck slow down. The exhaust brake is not on, I am not towing anything, etc. Also, when the truck shifts up, say from 5th gear to 6th gear, the boost gauge will go up to about 12-15 pounds while going downhill without the accelerator applied.

When I shut the truck off and get out, there is a smell of something very, very hot. This happens all of the time, so I cannot imagine it is re-gen.
Fluids check out, oil used is Rotella T6.

Truck is a 2017 F-350 6.7 with 8,100 miles on it.

Am I doing something stupid that I don't realize, or could this be a much larger issue?

TIA
 

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Discussion Starter #2
So I took it to the first dealer which is the closest to me in November. After 8 days with no contact, I called them and asked if the truck was done, and they said yes, they hooked it up to the computers and everything is fine.

I left the dealership and it was still acting up, so I called them and they said that they would not work on it because they didn't find anything wrong with it.

I then took it on a trip over some pretty steep grades (for the east coast) and I had to give it throttle to go down the hills without losing speed (was not towing and engine brake was not on). The steeper the hill, the more aggressive it was with slowing down. On a 7% grade the turbo stayed in the 22-24 psi range down the whole grade.

Called another dealer that is about an hour away and sent them video, they agreed something was not right and told me to bring it down to them. They were great at keeping me in the loop, but said that it is not an engine issue, but the torque converter is not locking/unlocking properly and that it will have to be replaced, which is going to happen on the 22nd.

Feel free to move this to a different forum since it is not an engine issue.
 

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Does it do it all the time? When in regen it will close the veins in the turbo to keep exhaust temps up when you let off and boost will jump to around 5psi.
 

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Discussion Starter #4 (Edited)
Yes, does it all of the time. Started doing it around 3600 miles, but it is much more noticeable in 6th gear at 65 mph+. At 75 mph, if you let off the throttle, turbo will be at 14-15 psi, going uphill, downhill, side hill :p

Going up a hill, it will lose 10 mph in about 2 seconds at highway speeds.
 

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Discussion Starter #6 (Edited)
So I am back again hoping to get some more feedback.

The torque converter was supposed to be replaced yesterday, but I got a call at 0900 saying that the transmission tech (that I had to wait 3 weeks for after they said it was a TC issue and needed replaced) drove the truck and didn't see anything wrong with it. So I asked them if they took it on the highway, and they said no, so I asked them to take it on the highway at 65 mph + and then let off the gas while not in tow/haul and with the engine brake completely turned off via the control panel.

So they did, and they said that they saw the boost go up when letting off of the throttle (about 12 psi) until the throttle is pressed again, but that was completely normal.

The truck did not do this when new, and the 3 other 2017 6.7's and one 2018 that I have driven do not do this.

Dealership says that there is nothing to fix, and I don't think that it is normal. Going down a steep grade, the truck will even shift down to 5th very aggressively to slow the truck down as soon as you let off the throttle, with all of the exhaust brake options off (and never touching the brakes).

Any ideas?
 

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Discussion Starter #7
Just another update.

Dealer called on Friday and said that transmission trech didn't find an issue, so I asked if I could send the video above, to which they said yes, and I did.

Didn't hear anything, so Tuesday morning I called the dealership, service manager asked if I could come down and drive it for him so he could see the issue with me behind the wheel. Told him that was fine, I would be there in about an hour (that is how far the drive is)

Arrived at the dealership, walked out to the truck, asked SM if he had the keys, he said he had no clue that I hadn't picked the vehicle up yet.

Once we were on the road, I showed him the issue I was having, even though it was not as evident because the hills in that area are not as steep, but he could still see the issue. Told him I didn't understand why when I brought the truck into the shop on the 7th that the diesel tech said he saw the issue and it seemed to be the torque converter not releasing, but I bring it back on the 22nd and the transmission tech says there is no issue. SM says he didn't know I had the truck in for previous diagnosis, and asked if we could talk to the diesel tech when we got back, which I quickly approved.

Arrived back at the dealership, went to talk to the diesel tech that said there was not an engine problem, but there was a problem. They had taken 2 new trucks off the lot to make sure that it wasn't just the way it should act, and neither of the new trucks showed the issue, so he figured it was the torque converter not releasing from the engine.

So then we talk to the transmission tech, who says that the transmission shifted fine, and the numbers looked fine. When the SM asked him if he checked the TC, he said no he didn't. The SM looked at me and said he thought we were done here, and he would call me when the truck was fixed.

Around 1630 that same day I got a call from the young lady at the service desk (who has been awesome and extremely patient with me) and said that they truck was done. I asked her what they found, and she said the transmission tech hooked it up to the computers and didn't find anything, so there was nothing to fix.

I am going today to pick it up from the dealership and plan to take it east for about 25 miles where there are some larger hills and take another video, and then I am going to ask the dealership if I can take a 2019 off the lot and do the same thing with it, and then put the videos side by side. That is about all I know that is left. I called Ford about the issue and they said that I needed to work with the dealership, and if I didn't like that dealership to take it to another (which this is the second dealership already).

Thanks for any help you can give me and letting me vent a little.
 

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Discussion Starter #8
So I am still in need of advice....

The dealership says that they cannot find anything wrong, and this will be the 5th time that it has been in the shop for the same issue. I have also contacted Ford and they told me I needed to work it out with the dealership.

Here is another video where you can see that the turbo goes up significantly when the accelerator is let off, but goes down immediately as soon as the accelerator is touched. Truck was not in regen during this video.

I am not allowed to post the link because of my post count, but go to youtube and use this url: watch?v=1E08KhyoV_I
 

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Well there's options..I guess. Keep going back, force the issue, maybe get a Buy Back? If that doesn't work maybe just drive the hell out of it knowing what your warranty time line is.


I really don't see a performance issue other than it's something you noticed. Is there some driving feel/problem associated with what you are experiencing??
 

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Discussion Starter #10
Essentially you can feel the truck slow down fairly quickly as soon as you let off the gas depending on the speed/grade. The faster the speed or the more the grade the more exaggerated it is.

It is just super annoying going downhill and having to give it fuel to maintain speed.
 

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RPMs seem to barley move....didn't seem like a transmission thing. Maybe it's the VGT side of the turbo??



Do you have any way to monitor the truck, like a Edge Insight or ForScan app??
 

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Set up to read RPMs, Boost PSI, Exhaust Back Pressure, Torque Convertor (not sure what PID it would be called), VGT (once again not sure of the PID), Maybe anything that shows Transmission Presssures.


I'm pretty sure you can data log those as well. I would hope then you could see the moment when something stands out as a discriminator to give you a better answer.

Where abouts are you located??
 

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Discussion Starter #14
Thanks again for the help. I am a systems engineer so I am sure I can figure out something, I just haven't had time with everything else going on to get ForScan running on my laptop.

I am located in North Central West Virginia, about 45 minutes south of Morgantown.
 

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I know its late, but...

Has any dealership at least just reflashed/updated the PCM? Sometimes a reflash can do wonders. This (to me) definitely seems like the computer is commanding an exhaust brake mode without the button being on. I doubt your veins are stuck because they release boost and spool just fine when you get back on the pedal. I also doubt it's a torque converter issue. It's generally locked anyway when in 6th and rolling..something is commanding your turbo veins to shut when you let off.

Ask for a reflash and send it...
 

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Discussion Starter #16
Sorry it has taken so long to respond.

I just got back from the dealer this afternoon. This was the 9th time the truck has been in the shop and it just turned over 15k.

They are able to replicate the issue, and have open up a tech ticket with Ford. Ford wants them to confirm the issue by driving a "like" vehicle, which I understand. If it is confirmed that it does not happen in the like vehicle, then they are supposed to proceed to Symptom Chart 6 found in PCED section 3. Problem is, they don't have a "like vehicle" on the lot, nor did the dealer have a time frame when they would have a like vehicle on the lot, so now I wait, again.

The information that the technician put in the ticket that they sent to Ford was extremely vague, so I can understand Ford's equally as vague response.

For the money of these trucks, this type of treatment is ridiculous. Along with it being a commercial vehicle, it is hard for me to want to keep it, let alone purchase another Ford at this point.

BTW, they did try a PCM flash and reprogramming the PCM the when it was in the shop earlier this week, but were unsuccessful in fixing the issue. Thanks for the suggestion though!
 

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Discussion Starter #17 (Edited)
Some progress

I hooked Forscan up to the truck and found a very interesting pattern, but I need some help interpreting the data for a better diagnosis. I have added files to show what I mean.

At exactly 53 mph and below, I stop having exhaust gas recirc commanded and measured, but anything above 53 miles an hour, I have an immediate command for 19.61% of exhaust gas recirc. It is always 19.61 percent no matter what speed above 53 mph I am at.

It doesn't matter if I am going uphill or downhill. As soon as I let off the gas above 53 mph you can feel the truck pull back.

Any extra times you would like to see, let me know, I have several recordings to pull from.
 

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I see some of what you are saying.



I'd say/ask the following: Isn't EGRTP the EGR system, maybe the throttle plate that drives the flow?? TCBP DSD isn't Boost PSI, but maybe the Absolute PSI of the atmosphere. (???)

As fas as TP% reading, were you using the cruise control?? You say Exhaust Brake is on, yet there isn't any thing really changing with Turbo WGate %. I'd expect a HUGE change when EB is applied.
 

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Do you have a 350 pickup or a 350 chassis cab? I am going to be going through utah next week on some 6% grades and can take a video of what mine does on the downhill if you have a pickup. Im assuming the chassis cab computer is different since the engine is rated different.
 

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Discussion Starter #20 (Edited)
I have a F350 Quad Cab 8' box.

If you all can give me the acronyms of what I should be adding for a test, I am more than willing to put them in and run the truck again. I have been dealing with this issue for over 2 years without any resolution, so I am more than motivated to do what I need to do.

No cruise control at all. I don't know that the exhaust brake is what is causing the slow down, I do know that I have to give it throttle to go down hill and that the turbo pressure kicks up to slow the truck down when I let off the throttle.

I am a systems engineer by trade, so the computer side is natural, I just don't know the right codes to have in Forscan to get the things that someone that knows the engine side needs to see. I just find it really odd that there was a very specific break at 53mph. Without Forscan I would not have gotten this far, so I am grateful for it and all your help!

:EDIT:

I added an attachment of what I was actually pulling.

:EDIT AGAIN:

I don't have the exhaust brake on, it just acts like it above 53 mph
 

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