On my '89, 5.0 5sp, I have a delay in the throttle. What I mean is that when I push on the pedal to give gas, then release the pedal, the engine seems to be a little behind in slowing down. I was told that the TPS may be the culprit. I have some neighbors who told me this, but they are Chevy guys and arn't too friendly to give me clearer advice. My question is twofold. Firstly, should this replacement be done with a new unit or can one be salvaged from the "yard"? Secondly, what complications can be expected when replacing this unit? I have no equipment to set timing, and I already don't trust this truck too much...... just yet.

 

if you have a multi-meter you could test it to see if it was good or not before you spend money on a new one. if you want to replace it, i've got a new one from the dealer, i don't need anymore.

 

+1 Dixie. It should read on a meter between .80 and 1.0 volts i think w/switch on and truck not running. Voltege will increase as throttle is givin. I just replaced mine to elemenate the posibility.
The only problem unless it has been removed before is the two small philips head screws are lock tite installed from factory and its easy to mess the heads of the screws up if you cant get good leverege on it. On my 96 it is mounted on the bottom of the TB Yours may be on the side im not sure. A new TPS will run you 58.00. You can do it yourself.

 

so what exactly is the difference between a TPS and a IAC ??

 

The TPS is the throttle position sensor, it tells the computer the position of the throttle. The IAC is the idle air control valve, it helps adjust the idle. They are independent of each other.

 

IACs are the devil

 

I had to replace mine this past summer on my 1990 5.0 this past summer. It was kinda a pain because of the location of it. I had to take the throttle body off to just get to the thing. The screws also was a little bit of pain but it solved my problem.

Another thing I am not too sure how different the 89 and 90 are but I would have your engine codes checked first because when mine was going out I got a check engine light.

 

I had to replace mine in my 92 as well, and had to take off the throttle body to fix it. My truck would hardly run before I replaced it, idle and run fine in park or neutral, but as soon as I shifted it into gear the rpms would drop and the truck would stall...

 

I read in a manual that when replacing the TPS you have to matchmark the location in relation to the TB (I think) otherwise you can jack up the idling or something along those lines. Therefore, it sounds as though it isn't a simple uncrew, remove and replace. Is that so?? The other thing is I haven't gotten a check engine light flash just yet so I am assuming it is alright, maybe just fatigued. I will try to test the resistance and see what i get. If the numbers are good, what else could it be??

 

It's not as bad as it sounds. There are versions with round screw holes that aren't adjustable, and there are versions with oblong holes that you can adjust. If you have a voltmeter, just make sure it's within range and you're pretty well good to go.

It adjusts in conjunction with the idle stop screw, which has a label on it reading "do not turn this screw" or something along those lines... It's a deal where you can follow the steps and do it right, or you can really screw things up.