So I think its my transmission, as I accelerate the truck shifts into the next gear at the right time, but after it shifts into the next gear it acts like it shifted too early and it lugs down. after reading some of the forums, I believe its the shift solenoid, but i also read one where it could be the mass air flow sensor. anyone else have an idea?
2004 F150 FX4 New body. 5.4L

 

The shift solenoid shifts the trans when the computer tells it to. I have never seen a shift solenoid that makes the trans shift too early. I don't see how that could happen.

 

Any OBD2 codes?

 

No codes are tripping. it started doing this after I moved across the country pulling a over loaded trailer. I have a Edge programmer and it was set to the level 2 tow tune during the trip, i had never used that tune before, and when i got here i put it back to the level 1 trans tune, it was shifting funny so i put it back to the stock tune, and it was still doing it. the trans fluid level is perfect, so i put some locus trans additive in it to see if that would help and it has not. Plus about march of 2011 I had the transmission completly rebuilt with all brand new parts, because after i bought it, the trans locked up on me, and I was refured by a very trusted friend, to a shop that is top notch with transmissions. they did a great job, and showed me all the parts they used before putting it back together, and the parts were not cheap parts. for the last 3 years i have not had any issues with it. but im also not easy on my truck. I work hard and play harder with it. I just want it running smooth again.

 

I would change the fluid and get the Lucas out of it.

 

the problom started before I put the lucas in it, that is not the issue.

 

I know it's not the problem, I just wouldn't want the Lucas in it.

 

Its not that it shifts to early its after it shifts the RPMs drop lower then normal into the next gear. For instance, just an example, if from first to second, normal shift would end in first gear at 2100 RPMs, and then start in second at 1500RPMs, mine is shifting into second starting at 1200RPMs, it still shifts into second from first at the right time, just it ends up being to low on RPMs in the next gear.

 

Maybe the torque converter is locking up when it shifts.