Bought a 3rd PSD a few months ago. 00 F250 SC auto. Trans was rebuilt around 20K ago by a local shop for the previous owner so out of warranty.

The problems. Running around stock it has always shifted hard and jerky but not terrible. Thought it might have been an in-house "Towing" rebuild. Always was eager to shift up to the point that it'd be in OD at 30 mph which made it get amazing mileage.

Threw in a DP F5 that I had laying around that happened to have the right emissions code for it. Now if its on anything but stock shifting is horrible. If you romp into it, it shift beautifully threw all gears but if you're just easing into it 1st-2nd with empty the dash and bark the tires. Second issue is it flat out wont go into overdrive under 62mph so on a 55mph road you're reving 2600RPM. Tune choice doesnt change anything. Chip worked flawlessly in 2 other trucks.

Fluid is clean and full. Temp doesn't effect anything. Torque converter seems to lock and unlock as it should. Ideas????

 

pull the dp ive herd of damage chips making trucks act odd. a while ago a guy put a 6 pos chip in his truck and it was having a problem with it. take it out and see if that does anything
best of luck

 

Goes back to still acting strange. Chip works perfect on 2 other trucks. Id blame the chip if it acted as it should when stock but since it doesnt Im assuming the chip is amplifying the problem not causing it but Ill be the first to say that an auto trans is a mystery to me.

 

hmm well they might have hooked up the tranny wrong or it may be the transfer case . im just trying to think what it could possibly be

 

Follow Up: With no chip it shifts firm but normal. Turns out the Trans shop put in "heavy spring to increase pressure manually". Any chip that touches the trans does the same thing (tried that DP, then a Ts, bullydog, and a Banks all for science sake). Took some bitching but they fixed it even tho it was out of warranty. Acts completely normal now when chipped and fine without.