Hi guys, long time no see.

I have a problem with my truck that has developed recently, and it is more severe when the A/C is running. It seems like the engine will not throttle up when going up a hill, and sometimes even when driving on flat ground. It's like the kick down doesn't work when driving in third or overdrive. The problem can also occur when starting off. The engine doesn't throttle up until a little further down the line. When it does, it goes like a bat out of hell as usual.

I can usually downshift and the throttle will respond. (not a good thing to do though)

Is this a throttle position sensor problem?

The tranny seems to shift nice and crisp when maunal shifting, and when in drive when thihs problem is not ocurring. It also occurs much more frequently when the A/C is on.

I'm a little puzzled with this.

 

Since yours is a 91 there is no TPS and the tranny is a 3 speed. Only 91.5 and newer have a TPS and on those it only controls when the overdrive is actuated.

Your problem sounds more like the kick down cable needs adjusted or it fell off and you might have the tranny serviced and have the bands adjusted.

 

I guess I'm a little confused by your problem. You're having a not-shifting problem, or a lack of power problem?

TSP only controls the shift between 3rd and 4th. Do you have problems with other shifts?

Sounds like it could be a plugged fuel filter. Do you notice any white smoke out the back during WOT? Other then that it could be other fuel delivery problems such as an issue in your injection pump. But I'd change the fuel filter first, then see what happens...pretty cheap and easy.

 

Thanks for the advice fellas. Mine is a 91.5, but since the problem can occur in other gears it's not the TPS. I'll adjust the bands, and change the fuel filter, and see what happens.

 

I may be off base here, but from what I'm getting from your post, it may be that what you are feeling is the turbo lag. when these turbo's spool-up it feels like they are downshifting. I wonder if the turbo is not spooling quick enough when you are running the ac because of the extra pull on the motor. maybe a boost leak. I'm just throwing ideas out for those who know more about the beast than I do. good luck Unclerety.

Tim