Originally posted by SlickGTP:
Damn... That's a lot of money for something that probably equates to a variable resistor. Unless they jack into the wiring harness, which for me is a big no-no.
I'd vote for the PCM. It's the correct way to tune.
A true happy knob goes along with a special pcm tune that will take advantage of specific resistor values for advancing the timing. Really, it's only beneficial for the track in my opinion.
Agree, but the happy knob is good for more than just the track.
I'm making my own right now. It is, just as you mentioned, just a variable resistance. It uses your intake air temp sensor connector. Normally the sensor's resistance changes with temperature, and your PCM will give you more timing when IAT's are colder, or less timing when IAT's are hotter. Somebody with a tuner can go into these control tables and put in whatever they want for certain temperatures. So if you put a certain resistance across the IAT sensor connector, it will adjust timing by a given value. I think there are about 12 different steps of adjustment.
I'm just using a three way switch for -2, 0, or +2 degrees timing. This will be useful for hot days, cold days, and different octane fuels. I can keep an eye on the KR via the aeroforce scangauge, and adjust global timing on the fly.