Throttle Position Sensor
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Joined: Aug 2000
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Re: Throttle Position Sensor (1990CORVETTE)
https://www.corvetteforum.com/techti...D=55&TopicID=2
There are 3 wires stacked vertically on the TPS. You will need to be able to measure the voltage between the two top wires. You can either buy a special harness connector that breaks these wires out (from Mid America), or gently pierce the insulation of the wires with the pointy prongs on your volt meter. You can also stick a paper clip into each of the two top locations of the connector and clamp onto the paper clips to measure the voltage. Whatever is easiest for you. · Turn the ignition to the “ON” position without starting the engine. · Loosen the TPS Torx adjustment screws. · Set your volt meter to a low scale DC volt setting that will accurately read less than 1 volt. · Measure the voltage between the two top TPS wires. · Adjust the TPS by rotating its position until you get a reading of .54 volts. · Tighten the Torx screws and recheck the voltage. Re-adjust if necessary to make sure voltage is right at .54. · Turn the ignition “OFF.” You are now in perfect adjustment on idle speed and TPS output. Start the engine. It may take a few seconds for the car to “catch on” to its new settings.
There are 3 wires stacked vertically on the TPS. You will need to be able to measure the voltage between the two top wires. You can either buy a special harness connector that breaks these wires out (from Mid America), or gently pierce the insulation of the wires with the pointy prongs on your volt meter. You can also stick a paper clip into each of the two top locations of the connector and clamp onto the paper clips to measure the voltage. Whatever is easiest for you. · Turn the ignition to the “ON” position without starting the engine. · Loosen the TPS Torx adjustment screws. · Set your volt meter to a low scale DC volt setting that will accurately read less than 1 volt. · Measure the voltage between the two top TPS wires. · Adjust the TPS by rotating its position until you get a reading of .54 volts. · Tighten the Torx screws and recheck the voltage. Re-adjust if necessary to make sure voltage is right at .54. · Turn the ignition “OFF.” You are now in perfect adjustment on idle speed and TPS output. Start the engine. It may take a few seconds for the car to “catch on” to its new settings.
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Joined: Feb 2004
Posts: 57
Likes: 0
From: Birmingham AL
Re: Throttle Position Sensor (1990CORVETTE)
Your throttle position sensor can be rotated. It's held in with two bolts. The stock TPS can be rotated only the tiniest amount, however, unless you are willing to cut its plastic bolt holes. An "adjustable" throttle position sensor simply has larger bolt holes such that you can rotate the physical position of the way that the TPS is lined up, and then you can tighten your two bolts down to hold the TPS in place.
Why does this matter?! Well, if you rotate your whole TPS unit clockwise, you will increase the output voltage of your sensor. This signals your ECU to increase power sooner than it otherwise would.
Stock TPS units will output .54 volts or less at idle. I've got mine set up to .60 volts, and some drivers have theirs set up to .65v.
So basicly, you want some way to measure your voltage output. MidAmerica sells an $11 wiring harness connector that allows you to hook your digital voltmeter in without cutting your Vette's wiring. If you want to save the money and time for mailing, then just splice into your TPS wires.
All 3 wires are easy to get to. On the harness, one wire is a ground (black), one is the power to the TPS unit (always outputs 5.00 volts), and the third wire (either blue or grey) is your sensor output voltage.
Loosen your two bolts that hold your TPS onto the throttle body. Turn your ignition to "on" but don't start your car. Measure your TPS sensor output voltage between the blue and the black wire and then between the grey and the black wire. That will show you 5 volts and .54 volts, normally.
Now rotate your TPS unit clockwise to increase your TPS sensor output voltage. When the unit is rotated to your desired position/voltage, tighten your two bolts down so that your TPS can't move anymore.
[Modified by nodoubt, 12:36 PM 2/23/2004]
Why does this matter?! Well, if you rotate your whole TPS unit clockwise, you will increase the output voltage of your sensor. This signals your ECU to increase power sooner than it otherwise would.
Stock TPS units will output .54 volts or less at idle. I've got mine set up to .60 volts, and some drivers have theirs set up to .65v.
So basicly, you want some way to measure your voltage output. MidAmerica sells an $11 wiring harness connector that allows you to hook your digital voltmeter in without cutting your Vette's wiring. If you want to save the money and time for mailing, then just splice into your TPS wires.
All 3 wires are easy to get to. On the harness, one wire is a ground (black), one is the power to the TPS unit (always outputs 5.00 volts), and the third wire (either blue or grey) is your sensor output voltage.
Loosen your two bolts that hold your TPS onto the throttle body. Turn your ignition to "on" but don't start your car. Measure your TPS sensor output voltage between the blue and the black wire and then between the grey and the black wire. That will show you 5 volts and .54 volts, normally.
Now rotate your TPS unit clockwise to increase your TPS sensor output voltage. When the unit is rotated to your desired position/voltage, tighten your two bolts down so that your TPS can't move anymore.
[Modified by nodoubt, 12:36 PM 2/23/2004]
