feedback carb throttle position sensor

[jiho]

I still have (in California) the Buick V6 everyone else here has already swapped out. Since it's an '83 it has the computer and (in California) it has smogcheck.

Recently it started acting up, including like it was trying to stall while accelerating at about 45-50 mph. So I checked the resistance on the TPS, across the middle (signal) and bottom (ground) pins, and found a dead spot between about 3.7-4.0 kOhms. So I ordered a brand new ACDelco replacement, which just arrived today. Testing it I find the same dead spot only narrower, at about 3.8 kOhms.

What's going on here? If I send this one back, will the exchange do the same thing? Are they all like this? Anyone have experience? Or even knowledge?

Thanks for your help.

EDIT: By "dead spot" I mean the multimeter reads "O.L." meaning "Overload: Range Exceeded."

 

[jiho]

Yes, I know there may be other reasons why it's "acting up," but right now I'm just trying to figure out the TPS. Wondering if this is some kind of signal pulse that tells the computer where the throttle actually is, regardless of how the TPS is adjusted, and not anything wrong with the TPS.

 

[fleming442]

Try moving the actuator slower through the dead spot. I've found most meters to be a little sluggish at times (try measuring voltage on a turn signal).

 

[jiho]

No no, it's just the opposite. If you move too fast you won't see it. You have to move real slow to catch it.

 

[fleming442]

No no, it's just the opposite. If you move too fast you won't see it. You have to move real slow to catch it.

That's what I'm tryin' ta tell ya!
So, you can land it on dead open, then?

 

[jiho]

Yes, but it's hard to stay dead on it. Just a tiny twitch and it goes away. Thing is though, it's always in the same spot -- and like I said, it's in the same spot on these two different TPSes. I think the one on the car is a Wells from Autozone, while this new one is ACDelco. Couldn't be more different, but they both do essentially the same thing. And with different multimeters, too.

 

[fleming442]

Well, I guess you have to ask yourself if that tiny little dead spot is enough to cause the problem? Do you really think a 1983 EPROM would react that quickly? I'm going to say no. Maybe start checking vacuum leaks, ignition pickup or module, etc...

 

[jiho]

I agree, it hardly seems likely that this would be the cause of my woes. Just wondering if anyone else has seen it, or happens to know about it. If this is a "feature" of this type of TPS, maybe that's why they have a reputation for not lasting very long. Maybe they're more durable than people think, and get blamed for things they don't cause.

EDIT: I think the Wells TPS that's on the car now was installed for this very reason. That was several years but less than 18k miles ago. Unfortunately my calendar note from the time only mentions "TPS follies" so I don't have the exact dead spot that prompted me to install the Wells. I love it when I do things like that.

 

[Clone TIE Pilot]

Maybe a bent plunger rod in the airhorn?

 

[jiho]

Clone -- You have the same TPS. What's your opinion on this dead spot being a "feature" of it?