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?

[ClayPerrine]

The TPS in a D-Jet system is not a variable resistor like modern FI systems. The "little squggily lines" you see are contacts that switch back and forth with the wiper contacts passing over them. They add additional pulses to the injectors for acceleration, same as the accelerator pump on a carb. The normal pulses trigger the injectors in pairs when that contact in the trigger points fire. The injector dwell determines the amount of fuel injected, and that is varied based on input from the MPS and the temp sensors.


Hope that helps...