Throttle Position Sensor (TPS), Dave, Brad and Cap'n and other FI experts Options

[mtndawg]

Can someone give me a good description of what the TPS signals to the ECU? My car was bucking when accelerating and when I would try to hold steady. I took the TPS out and cleaned it with electrical cleaner. It looks fairly worn and I get 18 clicks instead of 20. I think I'm supposed to hear 20. Now that it's clean (and adjusted) the car is running MUCH better, but I still hear only 18 clicks when I press the gas with the key on (and the engine off).

It's not bucking now, but now my idle is low at start when the engine is cold, then it's high (1500) when the engine is warm. I need to make some other adjustments, take a look at the trigger points and clean the screen at the bottom of the fuel tank too.

...so I want to know how the board and wipers signal the ECU?

[davesprinkle]

As a couple of other posts have mentioned, the djet TPS on the 914 is NOT like a modern TPS. It is NOT a resistive potentiometer. The 914 djet TPS has two functions:
1. It tells the ECU when the throttle is on the idle stop.
2. It tells the ECU to add more fuel on a throttle-opening transient, much like the accelerator pump on a Holley.

The Pelican site has a good description of the process to calibrate the TPS. Follow the steps or you're likely to have a poor idle.