I have a 2000 Expy w/ the 5.4L... At about 30-35MPH (and again at 40-45MPH) under light -reacceleration the RPMS rise to approx. 2k RPM then settles down to ~ 1500 RPM. After this happens, the truck seems to "lug" (Becomes REALLY sluggish) if I want to accelerate faster and the only way to stop this is to apply 1/2 to 3/4 throttle to kick down into a lower gear (like 2nd if in 3rd or 3rd if in OD).

I know this happens in 3rd and OD because at 30-35 when this occurs, hitting the O/D off button does nothing and again at ~45MPH hitting the O/D off button kicks the tranny back to 3rd.

I have about 28K now on the truck and have yet to do a tranny flush. I plan on doing it soon, but was wondering if my ECM needs a reprogramming? I've had the truck since it had 14K and this started happening at about 23k.

Any ideas?

Thanks in advance...

Ash

 

Yep, mine does this too. Seems to be the torque converter locking and unlocking. It will also do this at highway speeds sometimes going up small hills. It will also do this momentarily if I back out of the throttle and then get back on it at highway speeds.

When the convertor unlocks you get the extra revs and a resultant increase in torque.

It feels sluggish when the convertor locks up because of the lower revs and the locked situation. Just like a manual in a higher gear.

Hope this helps

 

That's exactly what I've experienced as well... Do you know if a superchip or shift-kit would help alleviate this? It gets REALLY annoying, especially on highways with many inclines. Around town I can just keep letting off and re-applying throttle if necessary (which I feel will wear down my tranny if I do this often).

Thanks!

 

I have the same problem as well. Mine only jumps about 200-300 RPM's when the truck is at 1500rpms. I have the Superchip and it does not cure this. Originally, I thought this was TPS sensor or Trans. range sensor problem, but after hearing several others complain about this, I guess this is common.