My car threw a Code 21 - "High Voltage at TPS" so I'm going to go ahead and put a new one in there, but..while I'm at it, is there anything else that could be causing this problem that I should look at too??

Also -- I can get an AC Delco TPS for a 85-89 cars (mine is a '92) I've heard the only difference is the 90-92 ones are NOT adjustable whereas the other ones are. This is fine by me but...

When I get a 85-89 sensor does it come preset or do I need to make some adjustments?? Subsequently, is it possible for them to go out of adjustment frequently?? My cars basically stock so I have no need to mess with it, so on one hand it would make more sense to buy the fixed sensor and be done with it – but – its proving a little hard to locate one right now.

 

Yes.

A code doesn't necessarily mean "the such-and-such is broke, change it out". Rather, it means that the ECM is seeing inputs that don't make any sense. In the case of the TPS, a typical "nonsense" set of readings would be high vacuum (light load, such as idling), low RPM, and high TPS voltage (throttle at WOT). Clearly this is a set of conditions that CANNOT POSSIBLY exist simultaneously. The ECM's programming recognizes this as an error condition, and by way of the principle contained in my signature, tells the service person that the most likely cause of the incompatible readings is the TPS. So, it's not impossible that something else is wrong; just, when the ECM sees that, it "knows" that the most likely explanation is a bad TPS, so start your troubleshooting there.

The adjustment consists of the exact location in which it is bolted on. The act of changing it out inherently de-adjusts it. So no, it doesn't come "preset". It's possible for it to come un-adjusted, if its hold-on screw loosens; but that won't generally set a code. It might though.