[Diy_efi] coolant temperature mod

[Bobby Riggs]

Update:  Apparently my logic is a little fuzzy :)
 Some people on a list I'm on said they have
noticed cylinder head temps go down as advance
goes up in highway driving.  In other words: If
you are too retarded (the engine) it will get
hot, starting the spark sooner (advancing it)
will cause the flame/combustion/explosion to be
done with sooner, therefore It has a little time
to cool before being slammed out the exhaust
port. Too advanced at idle is a bad thing for
startup.  But advance at > 2K RPM is really good
for highway cruise temps/economy. BTW: I work on
Aircooled motors so its ABSOLUTELY nessesary for
the CHT to stay LOW.  

Best thing to do is get a VDO CHT gauge and put
the sensor under the hottest spark plug for your
motor(#3 for me), tune and tweak watch the CHT to
see what it does for you!

--- Tom Cheung <tcheung at associated-labels.com>
wrote:
> anyone have info for import ecu's
> suzuki swift gti
> 
> will this mod advance or retard??
> 
> 
> Tom 
> 
> ----- Original Message ----- 
> From: "Bobby Riggs" <bobbyriggs at yahoo.com>
> To: <diy_efi at diy-efi.org>
> Sent: Saturday, June 15, 2002 2:10 PM
> Subject: Re: [Diy_efi] coolant temperature mod
> 
> 
> > 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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> >
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