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?

[r_towle]

If you only hear 18 clicks, you have not adjusted the TPS correctly and your Idle circuit will not be working right...
The poor idle is due to it being improperly adjusted and not contacting the Idle circuit portion of the switch...that is a special setting on Djet's ECU.

The Bucking while driving could be alot of things, but if its TPS related its due to worn contacts and worn grooves in the TPS...an poor adjustment.

First thing to do is adjust it properly.
The TPS is not really adjustable from one 914 to another...its designed to be mounted on many cars and many throttle bodies...
It gets adjusted ONCE for the specific physical setup or your throttle body, then its is static.
Its not meant to tune the car. There is only ONE place to set the TPS and that is the RIGHT setting..
I use capital letters to let you hear what I am saying clearly.
Djet does not use the tps like other cars...its a set it and forget it part.

Use the pic below to get it setup right.
Set it and forget it.
If the car still bucks, do your full tune up, grease the advance plates on the distributor, check the ground strap on the advance plates and reset your valves.
Typically one of the above is a contributor to the bucking...

The advance plates not being cleaned and greased, or the ground strap are the main causes...the valves adjusted poorly will make the car buck alot...especially if they are to tight.

Rich