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?

[Mike Bellis]

I can give you the generic version onf the TPS signal. While I don't regularly work of stock fuel injection, I do fab custom setups.

The TPS takes a 5 volt signal source from the ECU and varies the voltage between 1-5 volts back to the ECU. Most FI systems +/- 1 volt at no throttle and 5 volts at WOT.

Most TPS's have an physical adjustment on the mounting screws. This adjustmant is very slight. If you have removed yours for cleaning. I would summize the TPS is not back exactly in the original position. If you have a Volt Meter, you can probe the 3 wire to the TPS. One will be the voltage source (aprox 5 volts) one will be ground, one will be the signal back to the ECU. Loosten the TPS slightly, probe the signal wire and move the TPS body to achieve a lower voltage reading with the throttle closed. I do not have the exact voltage to give you. It is problably available from someone on this fourm.

I would guess your ECU thinks the throttle is already open and not giving you enough squirt for off idle take off. This is more typical for a speed density system. If you have a MAF the ECU is looking at both the Throttle position and air flow. these need to "sync" together for you particular fuel map to work best.

Hope this helps some...

Mike