93 gmc bogging and shifting hard..sometimes

[Cabinetman]

I’ve got a 93 gmc with the throttle body injected 305 in it. I’ve had a problem with it bogging out when I step it down down and when it does that it will shift hard into drive and shifting. Can anyone give me an idea if what could be wrong.

 

[Schurkey]

What is the fuel pressure?

How old are the usual "tune-up" parts--cap, rotor, plug wires, plugs, fuel and air filters, PCV?

How old is the O2 sensor?

Connect a scan tool, look at the data stream. See if there's any codes. Verify ALL sensors and computer outputs.

 

[Cabinetman]

After getting on the Google monster, I’m led to believe it could be the throttle position sensor. I’m going to try one and if it works, I will post it here.

 

[Schurkey]

This COULD be about a dozen different things.

Why don't you VERIFY the TPS before throwing time, money, effort, and enthusiasm on a new one?

A scan tool would allow you to check ALL the sensors in about ten--fifteen minutes.

A multimeter will allow you to check the TPS in about ten--fifteen minutes.

 

[Cabinetman]

Well I changed the throttle position sensor and it fixed the hard shifting problem. It’s like a different truck altogether. If anyone has one of these that bogs when you shove it to the floor in park and shifts into drive and reverse and first shift hard try changing that sensor. It very well could be your problem

 

[Sabinoerc]

Nice that fixed your problem! I had same symptoms once and low fuel pressure was cause.