[Diy_efi] coolant temperature mod

[Bobby Riggs]

In general this works fine!  I would only do it
to a manual trans car so you don't have to worry
about TCC.  In theroy the colder the motor, the
more retarded you need the timing to keep it
going..  When an engine is 'up to speed' you can
kick in the advance to keep it 'free wheeling'.
In other words its that little push you feel even
though the throttle is in the same posistion, its
an emission thing started in the '70s(when
vaccume advance became popular).

So Colder = Richer = more retarded

Hot = leaner until the "peak" where the computer
determines the engine is 'too hot' then its
starts to do a little preventative meassure by
retarding the spark and richening it up a little
to get the temps down in the heads mostly.
  At least thats my understanding.  Of course a
Jap. ecu is going to be different than a GM but
the same principal applies. just my 2 Cents 
-Bobby

--- Bruce <nacelp at bright.net> wrote:
> 
> 
> Without knowing all the coolant temp variables,
> your flitting with fire.
> EGR enable, TCC, CCP, are all likely to be
> dependent on it.   In general,
> not a good way to do things.
> Bruce
> 
> ----- Original Message -----
> From: "Tom Cheung"
> <tcheung at associated-labels.com>
> Subject: [Diy_efi] coolant temperature mod
> > does anyone know anything about putting a
> variable resistor between the
> > coolant temperature sensor and the ecu?
> > i have seen mods on the net on some toyota
> cars where they do this to make
> > the fuel mixture more rich and at the same
> increase the air flow sensor
> from
> > the MAF typically does this make the ecu
> adjust ignition timing since it
> thinks the
> > engine is colder than it really is? will it
> advance or retard your timing?
> 
> 
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