4R100 Hard 3-4 Shift Question - Diesel Forum - TheDieselStop.com
'99 & up 7.3L Power Stroke Engine and Drivetrain Discussion of the '99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.

 
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post #1 of 4 (permalink) Old 09-07-2010, 02:09 AM Thread Starter
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4R100 Hard 3-4 Shift Question

I'm new to posting on the forum, just been lurking for a few months.

I have been having a random 3-4 or 2-3 shift issue. It's kinda hard to tell because it's very random. Under moderate to hard acceleration the shift will be very hard. It won't do it consistently, usually it completely catches me by surprise. It doesn't matter if it's cold or hot. Sounds and feels like dropping the clutch on a manual transmission. I have a code reader that reads transmission codes and never get anything stored, no blinking OD light, etc. No burnt or discolored fluid, nice and pink. I did try changing the fluid and filter, didn't make a difference. My temperatures run around 130F normal and 150F towing. Other than the random shift issue it works perfectly. I would rather fix something simple first before it destroys the transmission. Reading some other posts I kinda suspected maybe it's a valve body issue, but I would like a second opinion.

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Brian

Early 1999 F-350 Lariat CC LB SWB 4x4, Upgraded PCM, DP Chip 60T 80E Decel, Ford AIS, Turbomaster, Boost, EGT, Trans Temp Guages, Hutch and Harpoon Mod, Delphi CPS, Prodigy P3 Brake Controller, 9K Fifth Wheel, 175k
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post #2 of 4 (permalink) Old 09-07-2010, 06:14 AM
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That would be my guess.

Mark
Former Automatic Transmission Engineer 1988-2007

“The good thing about science is that it's true whether or not you believe in it.” ― Neil deGrasse Tyson
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post #3 of 4 (permalink) Old 09-07-2010, 11:28 AM Thread Starter
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Thanks for the reply.

Which valve body should I be looking at? The accumulator or main valve body. I have access to a complete replacement set of valve bodies, so I can swap everything if needed. It's just a pain to change out all three with all the check balls etc.

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Brian

Early 1999 F-350 Lariat CC LB SWB 4x4, Upgraded PCM, DP Chip 60T 80E Decel, Ford AIS, Turbomaster, Boost, EGT, Trans Temp Guages, Hutch and Harpoon Mod, Delphi CPS, Prodigy P3 Brake Controller, 9K Fifth Wheel, 175k
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post #4 of 4 (permalink) Old 09-07-2010, 11:33 AM Thread Starter
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BD PressureLoc

I also noticed that the previous owner had put a BD PressureLoc module in the truck. Will this cause wierd shifting, or premature wear of the transmission? I have done a little research about them, but it doesn't seem real clear if it's a good thing to have or not.

Thanks

Brian

Early 1999 F-350 Lariat CC LB SWB 4x4, Upgraded PCM, DP Chip 60T 80E Decel, Ford AIS, Turbomaster, Boost, EGT, Trans Temp Guages, Hutch and Harpoon Mod, Delphi CPS, Prodigy P3 Brake Controller, 9K Fifth Wheel, 175k
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