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I have a 2K F250 7.3 liter with a 4R100 tranny. Engine is great but the tranny went south last June (2018). I had an experienced transmission man pull it and do a rebuild. He put a Sonnex kit in it and said he upgraded some other items in the unit (additional clutch plates, upgraded planetary gears?). Since then it has shifted very hard (seems to be) 3 into 4th gear. All other shift points are very nice with very sure and speedy shifts. 3-4 will knock a coffee out of you hand. It will almost chirp if you are on the go pedal hard.

He has since pulled the valve body out of the pan 4 times. Changing springs, checking for stuck or sticky valves, even replacing the whole body. There were no signs of this shift issue before the rebuild. The tech seems to think it may be a TC lock up issue? But.. I can feel one more shift after 4 when it goes into OD. We also installed a new TC and PP.

Not sure which way to go from here but he is talking about pulling the entire tranny out now and going over the entire rebuild. Other than the hard 3-4 shift, the tranny has been flawless over the past 14 months. No debris in the pan either.

Any suggestions? Anything outside of the tranny to try (sensors, programming?), although that would be odd since it was shifting fine before the rebuild.

Mark K., you still out there? Thank you
 

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The actual "shift points" you feel are 1-2, 2-3, TC lockup, and then 4th. You aren't feeling the TC AFTER 4th, you are feeling the TC lockup and THEN 4th. There are two different TC lockup strategies. One is a ON-OFF and the other is a Pulse Width Modulation. Mark will straighten out if this could be the cause, but if you apply the ON-OFF signal to one that should be a PWM it will be harsh.
 

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But.. I can feel one more shift after 4 when it goes into OD.
Fourth gear IS overdrive. You can't shift from fourth to fourth. One of the shifts you are feeling is the torque converter locking.

As RT said he may have mixed PWM and on/off parts in the build. If the solenoid body has an on/off solenoid for the converter clutch it will SLAM on. It will shift hard enough to knock a coffee cup out of your hand.

Ask the tech to measure the resistance of the TCC solenoid. A PWM solenoid should be around 5 ohms, and on/off is around 20 ohms. At least that's what my memory from over a decade ago remembers.
 

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Discussion Starter #4
Thanks gents, I sent Mike (Tech) a message and will see what he says...

If you send a digital on/off signal to a solenoid looking for a pulse width, that makes sense...

everything about the operation over the past year has been great except this lock-up. it runs nice through the 1-2 and 2-3 then bang (TC lock) then shifts nicely into the final 4th or OD gear.. You can run about 45-50 mph and get to the lock point.... keep raising the speed slowly and BANG.. then slow it down below the setpoint then BANG it comes out. You can do this all day long and it will bang in and out every time...

I'll report back after Mike checks it!
 

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The PCM in your 2000 is sending a PWM signal. If you have an on/off solenoid it won't do anything until the PWM signal gets high enough, and then BANG!
 

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I got the truck back on Sat night and there is no change. He did the solenoid swap and it was not the fix. He wants to pull the transmission out. He is thinking a pump issue? Any other suggestion before we go that route?

Thanks to all...
 

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Did he ohm out the old and new solenoid? Won’t make any difference if he’s putting the same type solenoid back in.


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He is thinking a pump issue?
How would the pump know to misbehave on a 3-4 shift, but then work correctly on the other shifts? Frankly, you'd be better off cleaning the windows to fix this than look at the pump. At least you'd have clean windows.

How many ohms was the TCC solenoid that was removed? How many ohms is the TCC solenoid currently in the transmission? I think you HAVE to have these two answers to fix this trans.
 

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all right guys... please hold the simple comments. I respect you guys and please offer me the same. I'm an Electrical Engineer and worked in the controls industry for 40 years. The tech has stopped communicating with me so i cannot answer the ohm question. I picked the truck up late Sat and he was not there. Now he is not returning my calls. I am trying to validate what was done, if anything. Next option is to take it somewhere else or pull it out myself...
 

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Yeah, some mechanics do not appreciate help from the 'interwebs'...no matter if its good or not. lol
Good luck OP
 

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all right guys... please hold the simple comments. I respect you guys and please offer me the same...

No one was being disrespectful. It was an illustration of the folly of doing something just to be doing something. You may not know this, but Mark was a Ford transmission engineer who had a hand in the design of the very transmission in your truck. If your guy won’t take his advice, you need to run.


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^^^^^ that is good advice
 

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Just overhauled. Main control and solenoids replaced or swapped. I might be thinking things like clutch pack clearance, damaged seals in the relevant hydraulic circuit and the overdrive clutch accumulator. The PCM controls the shifts monitoring the time it takes to complete them... a shift that takes too long will result in more pressure applied to that clutch to bring the shift time into specification and the result will be a harsh shift. If the PCM cannot compensate enough it will eventually set a code for the clutch having the issue. This is what we mean by adaptive strategy. With all of the control parts changed and no electrical faults indicated, it might be time to remove the transmission and have a careful disassembly performed looking at the most relevant parts. I wonder if this experienced transmission guy air checked this trans at any time.
 

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Yeah, some mechanics do not appreciate help from the 'interwebs'...no matter if its good or not. lol

Or well intended. I completely understand that angle of being helpful to the mechanic BUT, I personally have been burned too many times by "my mechanic" who provided codes, wrote them down wrong, cleared them and the accompanying freeze-frame data or codes that he caused poking around. I have been handed copies of technical service bulletins that don't apply or match the vehicle being worked on. I have had to adopt a no advice policy from the customers for these reasons.
 

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Or well intended. I completely understand that angle of being helpful to the mechanic BUT, I personally have been burned too many times by "my mechanic" who provided codes, wrote them down wrong, cleared them and the accompanying freeze-frame data or codes that he caused poking around. I have been handed copies of technical service bulletins that don't apply or match the vehicle being worked on. I have had to adopt a no advice policy from the customers for these reasons.
I completely understand that. Too many times you'll get "My brother's next door neighbor's diesel had a bad [insert component here], so that must be what's wrong with mine". :huh:
When I give advice here, it's always assumed that it's for a DIY fix, and I nearly always suggest pulling codes.
 
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