Prior to installing the ITB components into the Porsche, I decided that it was prudent to bench test the software and all the various sensors and signals. So I created a test file, and downloaded it to the TECgt engine management system. I wired-up the various sensors to the TECgt and verified that each signal was being recognized by the software. Although the TECgt specified a 10,000ohm TPS, it seemed my 5000ohm unit worked fine. I recorded a throttle-closed reading of .9volts, and a 100% open reading of 4.5 volts. Plenty of range for programming purposes. The manifold air temperature (MAT) sensor worked fine, as did the MAP (Manifold Air Pressure).
The only signal that I couldn’t get to work was the O2 sensor. I tried configuring the TECgt for a wideband input signal (0-5 volts) and narrowband (0-1 volt). I even tried a 1.5 volt battery. Regardless of the voltage, the software failed to recognize the signal input. I contacted Electromotive who were able to resolve the problem. It would appear that the TECgt ignores the O2 signal voltage until it sees the engine running for a specified period of time. I’m guessing that’s to give the O2 sensor time to warm up. I believe our Motronic performs a similar function, however it monitors the cylinder head temperature input. Once it sees the engine has warmed somewhat, it enables the O2 closed loop function. Time or temperature, I guess the effect is pretty much the same. The TECgt software allows the user to program the time delay. However I feel that monitoring engine temperature before entering into closed loop control is a superior solution. I’ll have to do some research to see if the TECgt can be configured to do the same thing.
Here are a few pics of the bench tests:
I’m away on business for the next little while, so my next progress report will be delayed.