Shifts hanging up under 3/4ths to FT....

[1994Diesel]

Shifts hanging up at 3/4ths to WOT....

I dont get it...

The '94 truck has been like this the day i bought it.

I just replaced the tach sensor and the TPS. It shifts much better now but i still have the shifts hanging up from 2nd to 3rd and 3rd to 4th. I can have it floored and it will drive in 2nd or 3rd gear all day with out shifting up UNLESS i ease up on the throttle. It will shift from 1st to 2nd under full throttle but it is an extremly delayed and sharp hard shift.

This problem is quite an issue driving on the freeway and making attempts to pass people.

What do you guys think the issue is?

Another thing to note is that i have adjusted the TPS to the correct volatage specs and yet the shifts still hang up.

thanks

 

[OLDBULL8]

More info needed.

What is the fluid level when hot? Overfilled above the full mark? Low below the add mark?

Last fluid and filter change?

Is the heat shield there next to the tranny harness connector on pass side?

 

[Black dawg]

What is the rpm when it won't upshift?

 

[icanfixall]

What do you have the new tps set at... They required voltage is .96 to 1.2 volts.. Seems a small amount but in reality it isn't.... At .96 the shifts are very soft and long... At 1.2 the shifts are crisper and harder....

 

[1994Diesel]

The fluid is On the T of HOT when hot. The last fluid and filter change was about 15k miles ago.

Heat shield? Yes there is one on the exhaust pipe coming from the turbo but on the cross over pipe there is not one.

It wont shift after 2500-2700 RPM.

I need to check again what the voltage was but i went off of the specs in the tech article.

 

[Black dawg]

what rpm will the engine get in neutral?

 

[1994Diesel]

The engine free revs at around 3000-3300. Its weird cause it seems that the last few hundred rpms take a bit longer.


a thought just came to me... since i have replaced the tachometer sensor i havn't free reved it, but i bet it clearly hit 3300rpm, which is the highest i have ever seen it.

 

[Black dawg]

so will the engine not go past 25-2700 wot in gear, or will it get to 3300?

 

[1994Diesel]

, it will go up to pretty much 3300 if i were to stay on it. It wont shift at WOT though. I rarely take it past 3k rpm though.

 

[1994Diesel]

Should i just make a video of this phenomenon? Would it be easier to diagnose for you guys?

 

[GenLightening]

Should i just make a video of this phenomenon? Would it be easier to diagnose for you guys?

Maybe not easier, but more entertaining!

 

[1994Diesel]

Maybe not easier, but more entertaining!

ok

Although it may not be for the weak of heart, I hate the way it just hangs up in gears and then shifts when i let off of the throttle.

 

[trackspeeder]

Play with the TPS a little more. The specs are ball park. Dial to your liking. Higher voltage will speed and firm up the shifts.

 

[ManicMike]

Under WOT I see the upshift at 3500. Has the valve body ever been dropped? Could be a stuck checkball or weak spring.

 

[1994Diesel]

Ok well i haven't been able to make a video yet. I've been pretty busy with classes this week.

I will try playing with the TPS a bit more like trackspeeder suggested.

@ManicMike: That is an interesting thought, I would not know if the valve body has been dropped though. The previous owner never supplied me with the info about the trans rebuild he claimed he had done, and the shop that did it lost all of there info on there computer.

Today while merging on the freeway, the on ramp was facing downhill, i floored it and the trans hung up in second gear but actually shifted and then hung up in third for a bit but shifted after a few seconds. The thing i have noticed is that it wont hang up as long or as bad when going downhill. I dunno if this has any significance.