The TPS has to be adjusted on all engines except the 4.9. Even if the check engine light isn't on there can be codes in memory.

 

the TPS didn't need adjusting on my 89 351...

I did have a code in memory and no light on... check codes before replacing.

 

The book doesn't lie, so you got lucky when you put it on or your truck will run better if you adjust it.

 

there is no adjustment. Round holes with screws. Unless I got out a dremel tool to make the holes longer, it goes on in only 1 way.

 

I had to adjust mine or came back that it was bad again. It wasn't that hard to adjust, you just put it on and until the tabs hold that thing and turn it until the holes line up and then put in your screws. Just can't remember if it's clockwise or counter clockwise.

 

Well that's odd. I don't have the 5.8 so I don't know 100%.

 

True there are two types, but the problem is I assume you won't know until you take it off, huh? Does anyone know when the adjustable one was changed or vise-versa?

Fig. 2: View of the throttle position sensor mounting-4.9L, 5.0L and 5.8L MFI engines shown, others similar


Fig. 3: Exploded view of the throttle body mounting-5.0L and 5.8L engines

Is there a difference between the two?? I have a 5.0 302, would there have been two versions in '89? What is MFI?

 

I asked for one at the auto parts store - the guy asked me if I wanted one that I could simply put on, or if I wanted an adjustable one that I could tweak. He brought both out and showed me. Supposedly both work for the same motor, but the non-adjustable one gives you sort of a pre-determined voltage.

 

So it sounds like the adjustment is on the TPS itself, and not on the throttle body? IF the non adjustment one works as it supposed to without given the option to tweak it, what would be the benefit in the adjustable one? Forgive me, I am just trying to make sense of the technology and interchangability (is that a word?!?!) of parts.

 

I'm no expert for sure... but you're supposed to have a certain voltage, and beyond getting within a range, I guess there's a sweet spot. Hence the adjustable TPS.

This site isn't for trucks, but gives a little bit of useful info:
http://www.smartworx.com/TurboTekToy...c/00000001.htm

If you have the 5.0 or 5.8, it's not in a really 'adjustable' location while mounted on the engine - the 4.9 has it on top (I think) of the throttle body, so it's easy to tinker with.