1981 VW Rabbit here for research (Build) (2024)

Verify your TPS tests as below.

PSIG wrote:TPS

TPS sensor must be of the 3 wire potentiometer type, rather than the 2 wire on/off switches found on some throttles. If your TPS is a 3 wire sensor then it will likely work, however you will need to confirm it is a potentiometer (variable) type sensor.

The TPS functions by sending an analog variable voltage signal to Speeduino in order to report the current position of the throttle. It is typically supplied with V+ of 5V and ground (GND, signal ground, or signal return), routing through an internal potentiometer to output a low voltage at low throttle opening, and a rising voltage with greater throttle opening.

If using a TPS with unknown connections; it is recommended to test the TPS with an ohm meter in order to determine the connection of each pin without risking damage by applying sensor power randomly. This can be accomplished on the bench or with the engine off and TPS disconnected:

• Assign a letter to each pin.
• Attach the ohm meter to two pins, and operate the throttle from closed (idle) to wide-open (WOT), recording the results.
• Find the pair of pins where the resistance does not change significantly from idle to WOT. These are your two power pins.
• The remaining pin is your Signal pin.
• In order to determine which power pin is V+ and which is GND, test ohms between the Signal pin and one power pin.
• In idle position; if ohms are low that power pin is GND. If ohms are high that power pin is V+.

Most usable TPS sensors have 3 pins. If your TPS has a different number of pins, referring to the original engine wiring diagram may show the function, and whether it is usable or which pins to use for Speeduino. For TP sensors that work 'backwards' or reversed (voltage decreases with throttle), and wiring cannot be changed, a simple code modification is available on the Forums to make use of this type of TPS.

Or find this old Speeduino info and many other helpful references at Archive.org:https://web.archive.org/web/20220804143310/https://speeduino.com/wiki/index.php/Hardware_requirements#TPS
Use care that some references are for use with older code.

Short answer, yes.
In spring I rewired my grounds and the tps while trying to figure out why it there was so much tps noise/movement. At the time the 5v and ground were reversed (according to what the Kia 0K24718911 tps called for). After correcting things it read in reverse when calibrating. In tunerstudio it gave me a heads up, but generally other users and faqs said the flipped values were fine. Overall it was doing alright until I got into Accel Enrichment. Now there is a large dead zone between no throttle and up to about 20 percent. The blade are opening but the tps doesn't register any movement. I adjusted the TPS mount mechanically but it didn't improve much. It's a second hand sensor that came with my adapter and it could be bad.

PSIG wrote: ↑Sun Jun 30, 2024 6:05 pmVerify your TPS tests as below.

PSIG wrote:TPS

TPS sensor must be of the 3 wire potentiometer type, rather than the 2 wire on/off switches found on some throttles. If your TPS is a 3 wire sensor then it will likely work, however you will need to confirm it is a potentiometer (variable) type sensor.

The TPS functions by sending an analog variable voltage signal to Speeduino in order to report the current position of the throttle. It is typically supplied with V+ of 5V and ground (GND, signal ground, or signal return), routing through an internal potentiometer to output a low voltage at low throttle opening, and a rising voltage with greater throttle opening.

If using a TPS with unknown connections; it is recommended to test the TPS with an ohm meter in order to determine the connection of each pin without risking damage by applying sensor power randomly. This can be accomplished on the bench or with the engine off and TPS disconnected:

• Assign a letter to each pin.
• Attach the ohm meter to two pins, and operate the throttle from closed (idle) to wide-open (WOT), recording the results.
• Find the pair of pins where the resistance does not change significantly from idle to WOT. These are your two power pins.
• The remaining pin is your Signal pin.
• In order to determine which power pin is V+ and which is GND, test ohms between the Signal pin and one power pin.
• In idle position; if ohms are low that power pin is GND. If ohms are high that power pin is V+.

Most usable TPS sensors have 3 pins. If your TPS has a different number of pins, referring to the original engine wiring diagram may show the function, and whether it is usable or which pins to use for Speeduino. For TP sensors that work 'backwards' or reversed (voltage decreases with throttle), and wiring cannot be changed, a simple code modification is available on the Forums to make use of this type of TPS.

Or find this old Speeduino info and many other helpful references at Archive.org:https://web.archive.org/web/20220804143310/https://speeduino.com/wiki/index.php/Hardware_requirements#TPS
Use care that some references are for use with older code.

soultron wrote: ↑Mon Jul 01, 2024 4:37 amNow there is a large dead zone between no throttle and up to about 20 percent. The blade are opening but the tps doesn't register any movement. I adjusted the TPS mount mechanically but it didn't improve much.

If physical adjustment to proper angle range does not solve the issue, then presumption is that the TPS is bad.

Random - most (not all) throttle bodies transition ±85°. Most (not all) TPS exceed this range, but minimally the full travel range of the TB.

After removing the assembly and testing it on the multimeter, the old one suddenly works more like an on-off switch. The new one goes up and down linearly and the leads are correct. I'm concerned there's more heat coming into this area than I would like and that may end up killing the new one as well. I'll see what I can do about sourcing or making my own heat shield.

*pictured with the sadfab miata/bosch tps adapter