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plumbcrazy

6 speed trans glitch

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Just purchased a 2016 Expedition XLT w/25000 miles. This is a beautiful truck. One owner , never a rental, not a scratch. I purchased it from a dealer 700 miles from my home. Long irrelevant story here....Anyway, the vehicle is still under original factory warranty. My problem is the transmission- 3rd gear specifically. Upon cold startup, the trans shifts as it should , into 3rd gear and pulls into 4th. Behaves exactly as it should and will go through the gears properly 2-3 times until it warms up even just a little bit. THEN, it will shift normally into third but almost immediately the rpms will drop and it "feels" like it went into 4th but it didn't. It seems to find a 3rd gear "high" This will occur under light and full load-- it doesn't matter. i've taken it to a local dealer and they say it's performing properly. I call BS. They say it doesn't produce a code but I don't accept that as an actual answer. Computers are not infallible. The whole driving experience is garbage in my mind. Still, I want to be reasonable. ( the dealer still has the vehicle and I haven't picked it up yet). There is no way this can be considered "normal" regardless of what the computer says. It feels like a torque converter that's lost pressure and slipping but it's only in 3rd gear. Extremely consistent behavior. NEVER happening in another gear. My 2011 F-150 with 6 speed auto and 175,000 trouble free miles shifts BETTER! I am hoping an experienced tech will see this and offer some guidance. I feel like my next move is to try to get a Ford Engineer on site to check this out. I'm discouraged and looking for help. THANKS!

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Expedition and F-Series use the same transmission, but not always the same shift strategy and 5 years is a long period of time between the two. You also didn't say which engine your 11 has, and those differences can be compounded by the difference between the two engines.  I can almost guarantee that your Expedition has a higher stall speed torque converter. I say all this because from your description, it SOUNDS like the torque converter clutch is locking in 3rd and you are seeing it on the Tach which is 100% normal operation. It does not lockup cold, as the engine and trans need to get to temperature as quickly as possible. Once it meets those temp thresholds, it starts allowing normal lockup strategy. The consistency you describe sure sounds like it is.

Of course, that is without me actually driving it. What needs to happen is a test drive and watch what the PCM is actually commanding vs what the trans and converter are actually doing, something any trans tech can do.  

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 I really appreciate your input. My F150 has a 3.7 flex fuel V6. I understand what you’re saying about the difference in age and vehicle but my concern is that I have never driven a vehicle that does this type of activity while still in a particular gear. I believe that the tech has driven around in the vehicle  with his diagnostic equipment and the conclusion it that it is that it is normal operation. I have two questions regarding this. Is it possible the diagnostics aren’t showing up as a fault because the problem is mechanical and not electrical? Also, when the torque converter locks up, and I understand what you mean when you say this, is it truly normal for the RPMs to drop so significantly when this happens?  If I drive an identical vehicle  on their lot am I going to experience the same thing? It sounds like you are telling me that I will. I appreciate your interest and I thank you in advance for your response.

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Trans strategy is going to be VASTLY different between the 3.7 and the 3.5 GTDI. There are a host of mechanical issues that do not translate into codes. That is why a test drive with what the PCM is commanding vs what it is actually doing is critical for the tech to do. IF the transmission is doing mechanically what it is being told to do, there is no issue with the trans. Not being able to drive it is also why a good diagnosis cannot be performed from the 3rd person. 

I would suggest driving another vehicle and compare to yours. From what I understand of your concern, I would think that the same vehicle would do the same things at the same point.  

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I want to thank you for your input. Turns out it is torque converter lockup and is normal. Thank you again.

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