Transmission acting weird

golfpro2301 · Jul 16, 2015

So I just got a used 2010 f250 Lariat. 112K miles. Has dpf delete and CAE with spartan tuner running 275 tune. Has f350 blocks in rear and 2 in level on front. Running 35x12.5. Now for the weird part. I drive it roughly 55 miles a day with 5 of it non highway. Drives perfect with the aggressive shift from 2-3. Today getting off the interstate I was slowing down and went to accelerate again and the engine just rev'd up and then transmission engaged pretty hard. Like I was accelerating as it was down shifting because I was slowing down. Got to the stop light and went to accelerate again slowly and got all the way to 30MPH before it shifted. It usually locks up at 48MPH. I am going to drive it out to dinner tonight and will see what happens but does anyone have any idea why it is shifting so late?

Powerstroke Man 6.4 · Jul 16, 2015

golfpro2301 said:
So I just got a used 2010 f250 Lariat. 112K miles. Has dpf delete and CAE with spartan tuner running 275 tune. Has f350 blocks in rear and 2 in level on front. Running 35x12.5. Now for the weird part. I drive it roughly 55 miles a day with 5 of it non highway. Drives perfect with the aggressive shift from 2-3. Today getting off the interstate I was slowing down and went to accelerate again and the engine just rev'd up and then transmission engaged pretty hard. Like I was accelerating as it was down shifting because I was slowing down. Got to the stop light and went to accelerate again slowly and got all the way to 30MPH before it shifted. It usually locks up at 48MPH. I am going to drive it out to dinner tonight and will see what happens but does anyone have any idea why it is shifting so late?

Rev-slam its known to do it all the time with Spartan tunes.