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My 95 F250 has a very late shift from 1st to 2nd under heavy throttle getting on the highway. The motor is turning 3000 RPM and I'm only doing 30MPH, I have to back out of the gas to get to up shift to 2nd then a delayed shift into 3rd. It's shift ok at light throttle on the city streets 1st into 2nd at 1200 - 1500 RPM, 2nd to 3rd at 1800 - 2000 RPM and into OD. I had the issue before I had the transmission rebuilt new TC, Center Support Kit, Valve Kit, Solenoid, Clutch's, Shift Kit. I've replaced the VSS, TPS and MLPS. I'm not getting any codes and there's nothing odd in the live data. Has anyone else seen a light throttle - heavy throttle shift problem? 

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Welcome to the forums, NVSuperDuty...Glad you noted that this problem existed before your rebuild with a laundry list of upgrades.  You've also addressed several of the common speed signal related issues on Ford E4OD systems (VSS, TPS and MLPS).

Since you are not getting a code(s) or live data indications of trouble, the problem points toward the hydraulic/mechanical side of the system.  I would check out the EPC solenoid, which could be defective or sticking.  I'm guessing you've done each of the Ford Self-Tests and scanned for codes, or I would suggest doing all of that to rule out the PCM, PSOM, TP, TOT, EPC, SS1/SS2, etc.

Note:  If a diesel Powerstroke model, I would check the FIPL/TPS sensor settings.

If not electrical or electronic, you're looking for something mechanical that was not addressed during the rebuild...

Moses

 

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Thanks Moses,

 I was thinking along the line of fluid pressure too since I'm not getting any codes and the electronic items I've checked so far have been spot on for voltage or resistance.  I do get a loud sound in 1st and 2nd like an 18 wheeler in low gear, it's not as loud in 3rd and sound normal in OD. I did ask the tech if this problem could be from a failing pump and he said no, I'm not to sure about that one. I still need to do more looking into pump failure. 

Jeff

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Jeff...I would run an external port (classic) pressure check, it's easy enough to do and very useful.  Since the problem existed before and after the rebuild, a pressure check might be telling...I'll watch for your results and findings.

On the other note, the higher pitch noise in lower gears is a clue.  Consider the parts that rotate faster in the reduction gears.  3rd is 1:1 and 4th overdrives.  Noise could be from a reduction member.

Moses

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