Original Author: Phil Barnett (prb) - 2013
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The TPS (Throttle Position Sensor) is part of the computer control system of your engine. The computer uses this signal to know the position of the throttle is (yeah, that makes sense, duh).
Why does the computer want to know this? Well, there are several reasons. First, there is a switch that signals when you let your foot completely off the gas. This tells the computer that you are coasting. Above a certain RPM, the computer responds to this by cutting the injector signals completely off, thus depriving the engine of fuel while you coast.
Second, it gives the computer a way to understand how hard you are wanting to accelerate. With this signal, the ECU can retard timing to give you more power or advance timing to give you better fuel economy.
Finally, if the TPS is not adjusted correctly, you may have issues with your idle.
The TPS on the 1.6 liter engines has two switches in it. One that indicates throttle closed and one that indicates WOT (wide open throttle).
The TPS on the 1.8 liter engine was a little more sophisticated, it has a throttle closed switch and a variable resistor to indicate percentage of throttle opening. This allows the 1.8 computer to do a little better job of assessing the demands between no throttle and WOT.
POW - Indicates Wide Open Throttle
TL - Common
IDL - Indicates Throttle Closed
This is a double pole single double throw switch with the center off.
The common terminal is TL.
With the wiring harness disconnected and the TPS still in place on the throttle body, using an ohmmeter:
With the throttle at rest (and properly adjusted), there will be continuity between TL and IDL.
With the throttle at maximum, there will be continuity between TL and POW.
With a .016 inch feeler gauge inserted at the throttle stop screw, you should have continuity.
With a .027 feeler gauge inserted, no continuity.
If adjustment is needed, loosen the TPS screws and rotate the sensor to achieve these results.
AB are the variable resistor and CD are the idle switch.
With an ohmmeter on the 20k scale, AB reads 3.82 static and when rotated decreases linearly down to .52 against the WOT position.
Connectors CD are shorted in static position and open when rotated off idle position.
From my measurements I conclude that both of these TPS are good.
Average readings for AB (for the two I tested) are ~3700 ohms in idle position and ~520 ohms at WOT.
With a .012 inch feeler gauge inserted at the throttle stop screw, you should have continuity between C&D.
With a .016 feeler gauge inserted, no continuity.
If adjustment is needed, loosen the TPS screws and rotate the sensor to achieve these results.
You can also verify the variable resistor by measuring voltage at the 2M connector at the ECM (ignition switch on). Full closed is should be .1-1.1V, fully open 3.1-4.5V.
Back to Maintenance
The TPS (Throttle Position Sensor) is part of the computer control system of your engine. The computer uses this signal to know the position of the throttle is (yeah, that makes sense, duh).
Why does the computer want to know this? Well, there are several reasons. First, there is a switch that signals when you let your foot completely off the gas. This tells the computer that you are coasting. Above a certain RPM, the computer responds to this by cutting the injector signals completely off, thus depriving the engine of fuel while you coast.
Second, it gives the computer a way to understand how hard you are wanting to accelerate. With this signal, the ECU can retard timing to give you more power or advance timing to give you better fuel economy.
Finally, if the TPS is not adjusted correctly, you may have issues with your idle.
The TPS on the 1.6 liter engines has two switches in it. One that indicates throttle closed and one that indicates WOT (wide open throttle).
The TPS on the 1.8 liter engine was a little more sophisticated, it has a throttle closed switch and a variable resistor to indicate percentage of throttle opening. This allows the 1.8 computer to do a little better job of assessing the demands between no throttle and WOT.
Testing the 1.6 TPS
From the top to the bottom, the terminal names are:POW - Indicates Wide Open Throttle
TL - Common
IDL - Indicates Throttle Closed
This is a double pole single double throw switch with the center off.
The common terminal is TL.
With the wiring harness disconnected and the TPS still in place on the throttle body, using an ohmmeter:
With the throttle at rest (and properly adjusted), there will be continuity between TL and IDL.
With the throttle at maximum, there will be continuity between TL and POW.
Adjusting the 1.6 TPS
Using an Ohm meter, measure for continuity between terminals TL and IDL:With a .016 inch feeler gauge inserted at the throttle stop screw, you should have continuity.
With a .027 feeler gauge inserted, no continuity.
If adjustment is needed, loosen the TPS screws and rotate the sensor to achieve these results.
Testing the 1.8 TPS
The lettering scheme is ABCD from top to bottom as seen from the front of the car.AB are the variable resistor and CD are the idle switch.
With an ohmmeter on the 20k scale, AB reads 3.82 static and when rotated decreases linearly down to .52 against the WOT position.
Connectors CD are shorted in static position and open when rotated off idle position.
From my measurements I conclude that both of these TPS are good.
Average readings for AB (for the two I tested) are ~3700 ohms in idle position and ~520 ohms at WOT.
Adjusting the 1.8 TPS
Using an Ohm meter, measure for continuity between pins C & D in the actual TPS unit.With a .012 inch feeler gauge inserted at the throttle stop screw, you should have continuity between C&D.
With a .016 feeler gauge inserted, no continuity.
If adjustment is needed, loosen the TPS screws and rotate the sensor to achieve these results.
You can also verify the variable resistor by measuring voltage at the 2M connector at the ECM (ignition switch on). Full closed is should be .1-1.1V, fully open 3.1-4.5V.