Transmission shift problems while tuned up

[Alex C]

04 power stroke 6.0 automatic


So for a while, i ran the diablo sport predator programmer and it worked great. A friend of mine was in the truck at a gas station and while filling up i changed the tune on the predator sport. when i walked out he had started the truck, not paying attention to the programmer being plugged in. I told him that i was in the middle of tuning the truck and to grab the programmer and look at what teh screen said. The programmer said that it had sensed the truck starting and was restoring the pcm to factory back up tune. We re tuned it to the 100 hp tune and shortly after leaving the gas station, we were driving around 30 mph accelerating normally to about 45 and the RPMs pegged out as if I had thrown it in neutral. It was so bad that i had to pull over because i was slowing traffic. I immediately restored the stock tune and it was acting up a bit, but not too bad and after a week on the factory tune, the problem went away. Now, i have an edge juice with attitude and I am having serious shifting problems on the tunes 3-5. Stock tune, milage, and towing tunes (0-2) under full acceleration shift fine and the transmission doesnt act up but on especially 4 and 5 (100-115hp) the once i hit about 60 mph it just pegs out at redline and wont up shift. Some times i can take my foot off the pedal and gently push on the accelerator and once in a while it will up shift ok. Once in a while, after this occurs a few times in a single trip, the the transmission will clunk and the tow/haul light will start flashing and not stop until you shut the truck off and restart. Also, at this time the overdrive will not work and you cant go past 70 mph without getting near redline....Funny enough, it has firm shifts though when this occurs. If the tow haul light does not come on after the problem occurs and when i come to a stop, while in the same 4 or 5 tune, and i try to accelerate, it seems as if i were driving a standard transmission with the clutch depressed half way, and then if i get on it a bit more you'll feel the transmission lock up and fully engage. When i return it to the stock tune after this, it works fine.

Ive pulled out the chip twice and brought it to the dealership and they said the transmission is fine. (which is true in stock tune) Its just under tune that it slips.

Sorry for the novel, any ideas? and yes my transmission fluid level is fine.

[redneckracer81]

I am having this same problem with my 06, Did you ever find out what was causing it?

[Mikesf250]

My SCT when you change tunes you have to kind of have to baby it for a while then hammer on it. Because I think the tranny has to learn the new program. My truck would wind out then it would feel like someone rearended me between 3 and 4 but after someone told me to try that it works fine

[towbeast03]

I have an sct also and it lets go then kinda slams into the next gear just like mikesf250 explained its pretty scarry, any thoughts on what this is or are the sct tunes just junk....about six months ago my truck did the same thing as alex c and I put it back to stock and forgot about the programmer then one day I started farting around with the programmer, called sct and updated it, worked fine but now its shifting funny again. GRRR...

[Tailboard Jockey]

My truck did this a few times a couple of years ago, and it turned out to be a bad solenoid in the transmission.

It happened to me again on Christmas day. I was merging onto the freeway and got on it a little bit. All of a sudden, it was like I was in neutral, and my RPMs went up to 4500. I just had my transmission serviced about 2 months ago.

We were going to my Mom's house, about a 2 hour drive. We were close to home when it happened, and I told my wife that if it happens again, we're turning around and going home. It didn't do it again, so we made it there and back with no problems since then.

[Stakk]

for what it's worth I have stock 04 250 with the Diablo also, I floowed the direction to a tee everytime I have reflashed the curves and it works......meaning I do not go full throttle shifts until the 5 cold starts, this will take about 5 mornings starting your truck for the tranny to adapt, I tried to run it before this learning process, and the tranny didn't know what to do, I gave it time to do the 5 cold start adaptation, and it shifts fine now......hard to keep your foot out of it thought while it's learning