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sliverstorm said:
Figures. Why would it be right-side up, that would make things too easy. Though it still looks to me like there is no *switch*- which really makes a lot of sense to me. The simpler it is, the better; esp. when it will move a bajillion times during it's life. Just think of how many times you've moved your gas pedal.
I don't care whether or not you think it would make sense for there to be a switch, that doesn't actually have much bearing on whether or not there is a switch.

There is a diagram at the top of FI-58 that clearly shows a switch between E2 and IDL. The chart that you showed, clearly shows that the resistance between IDL and E2 changes drastically from < 2k ohms to open circuit over a very very narrow amount of movement. How could that be anything other than a switch?

But you want a reason why there'd be a switch? The TPS isn't very accurate, and it serves multiple purposes. One thing that it does is tell the computer that the throttle position has quickly changed. The airflow meter isn't really fast enough to keep up with fast transients, so a good approximation from the TPS is helpful. If you are cruising with constant speed, the TPS is next to worthless between the AFM and the O2 sensor.

The TPS is also used to inform the computer if its at WOT or idle. It needs to know idle very accurately because it has to do a host of things to keep the car idling properly when your foot isn't on the throttle so it has to be very accurate. The potentiometer just isn't that great for that purpose, especially when its near one end. On otherhand, WOT isn't as critical, since WOT only really engages the extra-enrichment, and does it really matter if that enrichment comes in at 90% WOT or 100%? Not really.
 

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Yeah, I know it doesn't change whether there is a switch or not, but logic+that diagram I posted was all I had. (I was looking at an '88 book, didn't *have* the diagram from your book) I also get the feeling that your definition of a switch might be a little different than mine, but I've run into that problem before. plz refrain from getting so irritated so fast in the future -_-
 

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The function of the switch that causes all of the trouble is the fuel shutoff. When you lift off the throttle at driving speed, the ECU cuts off fuel completely, based on the rational assumption that you don't need to waste fuel while you are slowing the car. If that switch closes before the throttle is actually closed, then you get a very unpleasant lurch. That is why the switch position needs fine adjustment.
 

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sliverstorm said:
I also get the feeling that your definition of a switch might be a little different than mine,
I think that is the problem here. It is not a switch in that you don't push it or flip a lever or anything like that. The way I see it is that it opens and closes a circuit. That is a switch.
 

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Any chance that this throttle sensor will disable the cruise control? I have checked all other parts and replaced the clutch, brake, parking brake switches. I have replaced the control module, and checked the speed sensor, actuator and cruise control switch on the steering wheel. I still have no cruise control function. The last part the service manual says to check is the throttle position sensor. Any advice would be most welcome. Mine is a 91 S20 with 2.2 base engine. Please advise. Thank you 😊.
 

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2 Williamw9125: I would check first the steering wheel spiral cable assy (you have your Cruise Control switch on the steering wheel, right?).
And yep, the TPS may have influence on operation of cruise control. Check resistance between pins mentioned above to see if it works.

Cheers
Paul
 
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