when i am going down the highway at about 70 MPH, my transmission wont shift to 4th gear until i let go of the gas, it will stay at about 3500 rpm, and when i let off the gas drop down to about 1500-2000, but when i put the gear selector in 3rd gear and let off the gas, the rpm does not drop as drastically, so i know it can shift to 4th, but it does not want to when the throttle is applied. I know i have a bad Throttle position sensor, which i have and am going to replace. Would a bad TPS cause this kind of problem ? because the ECU thinks i am pushing the throttle more than i really am ? My other philosophy is that the engine was running so bad (this is back when i first bought the car and it had many engine/ intake issues so bad people were honking at me from a stop light. Note also that i have been working on the car for a while fixing head/engine/intake issues) that i had to push the throttle more than i should have been to keep the car at 70 mph for it was running way below optimal output, which in turn may have caused the engine to think it needed to downshift for "Passing Mode". Or it may be a combination of these things, as well as the fact that the transmission has stock fluid at 180k+ miles.(odometer stopped working as well -.-) Do any of these sound feasible or is it a more serious problem ? (on another note i was swindled when i bought the car for $1700 as the owner said the only problem was a "Clogged catalytic converter). Boy was i upset when i found all the things wrong with it. But nonetheless i hope it will be a top notch machine when i am done with it. If anyone has any ideas on what i should do, please feel free to shoot away, Thanks.

 

Id replace the TPS if you know its bad and go from there....

Take it to a trans place or the dealer that can read trans codes and see if there are any present

 

there was a trans code that said "Gear 4 incorrect ratio". also the fluid is a bit dark, as i am fairly sure it is stock fluid, so i will have it changed out and see if that fixes it.

 

It doesn't make any sense to play "what if" with your transmission when you know you have a bad part in there. Replace the TPS and see what the transmission does then.

 

i have the new tps installed, but i still need to install the intake manifold, airbox, cam cover, injectors, fuel rail, spark plugs/wires, inter cooler plumbing, turbo/exhaust manifold heat shield, figure out all the vacuum lines. Along with all the fun of figuring out what bolts go where, so if everything goes as planned and luck is with me it will be done by late Sunday afternoon.

 

I think that 10mm torx bolt is right over there