Another Throttle position sensor problem

Does anyone know what the voltage should be at idle and what it should be at WOT? I know the TPS is pretty much an on/off switch

Here is the problem i am having, with the TPS plugged in and adjusted properly the car wont rev pass 2000 RPM. it just cuts out then revs to 2k again then cuts out and it keeps doing this in a loop if i hold the throttle steady. i have a nissan sentra SE-R TB and it opens in the opposite direction of the toyota.

here is what i discovered, with the TPS disconnected the car drives perfect. when i adjust the tps so the middle pin is not touching any of the other 2 pins the car revs fine and the AFC reads 5 volts. (the same effect as disconnecting the tps) when the tps is in the WOT position the afc read zero voltage. It seems to me as if this is backwards, can anyone help shed some light. Thanks. See pics below for better understanding.

3 wires for the tps im wondering if the bottom yellow/red wires have switch position in the harness? notice how one loops over the other? I'm thinking maybe the person that installed my AFC swapped these around since the nissan TB closed position would be wot on the toyota tps?



This pic show the tps in idle position as it would be if bolted on the TB. With these 2 pins touching the AFC read 5.0V



With the middle pin in this position, not touching either, the car revs and drives fine but runs a little rich so i use the afc to lean out. the AFC still reads 5.0 V



With the middle pin touching the bottom at WOT i get 0 V on the AFC



why does not rev past 2k when the middle and top pins touch (brown and yellow/red), reading 5 volts vs when the 2 pins are not touching it still reads 5 volts but revs past 2k?

The stock ECU will fuel cut at 2000rpm when the IDL pin is grounded. That's basically what the idle switch in the TPS does, shorts the IDL (5v) to E2 sensor ground (middle pin of connector) when the throttle is closed.

Both the IDL and PSW pins are fed 5v via the ECU's VCC.

With the throttle closed voltages should read:

IDL - 0v
E2 - 0v
PSW - 5v

With the throttle halfway the voltages should read:

IDL - 5v
E2 - 0v
PSW - 5v


With the throttle wide open (approx +75%) the voltages should read:

IDL - 5v
E2 - 0v
PSW - 0v

thanks this helps alot something is messed up with my wiring at idle im reading 5v then 5v half way then 0 at WOT

If you are using a throttle body that rotates the butterfly in the opposite direction the stock tps wont work with it. Its either find another throttle body or see if the plate can be swapped around to allow it to rotate in the other direction.

weeJohn said:

If you are using a throttle body that rotates the butterfly in the opposite direction the stock tps wont work with it. Its either find another throttle body or see if the plate can be swapped around to allow it to rotate in the other direction.

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Why do you think so? wouldn't switching the wires around in the TPS connector achieve the right results?

the other thing im confused about is the car drives great with the tps unplugged. so what is the real purpose of the tps other than just making the car burn less gas at idle? i can compensate for that with the AFC settings

i have a similar issue ive yet to deal with, can i ask.. when your rev the car can you rev over 2000rpm or is that the maximum you can rev to, i have an issue where i i can drive up and over 2000rpm but after a few seconds of being over 2000 it will cut out injectors untill back under 2k, but i can actually get over 2000rpm with WOT accelaration

goldenvtr said:

i have a similar issue ive yet to deal with, can i ask.. when your rev the car can you rev over 2000rpm or is that the maximum you can rev to, i have an issue where i i can drive up and over 2000rpm but after a few seconds of being over 2000 it will cut out injectors untill back under 2k, but i can actually get over 2000rpm with WOT accelaration

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I've never actually drove the car like that. I just tried to rev it in neutral, i would not go past 2000 rpms. however i think i know what you are talking about, when i first started experiencing the problem the car would move off from a standstill fine and accelerate fine until i hit 2 k it would cut out but give it more gas as maybe after a 1 sec delay the car would go. Its like the ECU though it was in idle but i guess eventually it realizes (prob from the speed sensor) that the car is in motion and needs more fuel.

4eftetercel said:

Why do you think so? wouldn't switching the wires around in the TPS connector achieve the right results?

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You can swap the wires over to read right at idle or wide open throttle, but not both. You could fit a limit switch that is activated by the throttle wire cam for the open throttle, like on a nitrous system.