Throttle Position Switch Tester
Another project is a test set for the 914 throttle position switch. This is just a little perf-board with 3 LEDs and a resistor. It plugs into the connector on the TPS and the other ends clip onto 12V. The green LED glows when the "closed" contacts are working and the other 2 red LEDs glow as the "accelerator pump" contacts alternately make and break. This makes it very easy to see if the TPS is working and is adjusted correctly...plus I use it to adjust the TPS.
TPS Test Set (22 kb) TPS Test Set #2 (21 kb) Schematic of TPS Test Set (10 kb)
The TB in the above picture is a modified one that has the throat diameter bored out to about 120% of the stock size. I don't normally use it, but it was installed when the picture was taken. Yes, the big TB gives more performance when combined with slightly higher fuel pressure.