op-amps

[Frederic Breitwieser]

> "warm up" mode.  Can an op-amp be used to achieve the same result?

I don't see why not.  There are no laws against lying to your ECM.  In fact,
when I started building my twin-turbo V6, the ECM I had (FWD naturally
aspirated 148) had no idea it had a turbo.  I adjusted the sensors using
op-amps so the ecm thought it had less air going into it than it really did.
Of course, the sensor maxed out and the OP amp's output then of course maxed
out half way of what the ECM thought WOT would be in regards to airflow.  So,
time to add voltage to the op-amp and sum it together.  Wasn't perfect, and
didn't play with it that long, but you can lie to your ECM.  The issue is you
have to do a lot of lying.  I found out the hard way you can't just modify one
sensor... you need several.

A common trick is to install a resistor in series with the water temp sensor,
and put a switch in parallel to the resistor.  When the resistor is in the
circuit, i.e. switch open, the ECM thinks the engine is cold, and richens the
mixture -somewhat-.

> Another tip was to put a 2nd water temperature sensor in the windshield
> fluid container and wire this to a switch in conjunction with the normal
> water temperature wiring.  Could an op-amp be used instead of this set up?

Aaah, I should have read your post entirely.  Um, yes :)  A temp sensor is a
heat sensistive resistor, so you'd need to make a wheatstone bridge. :)