Re:was resistor in the O2 loop now AFM flap shennanigans

[alex.fadeev@xxxxxxxxxxx]

kohlbren-m-d@domain.elided wrote:
> John Bolhuis <bolhuijo@domain.elided> wrote:
> 
> > On Wed, 15 Jan 2003 kohlbren-m-d@domain.elided wrote:
> > 
> > > > As for full throttle operation when the O2 sensor is ignored
> > > > by the ECU, the AFM flap is fully open above 3000 RPM or so.
> > > > Adjusting the flap spring pressure a little will do nothing 
> > > > for you in the "fun zone" of RPMs and throttle.
> > > 
> > > I don't deny that this could be true.  However, if it is, 
> > > how, then does the computer know how much fuel to squirt 
> > > at WOT/high rpm?
> > 
> > At WOT, the ECU relies on an internal map to deliver a given 
> > amount of fuel for a given RPM.  It tends to be on the rich 
> > side of stoic for safety.  (except above 6k RPM on my e30, 
> > where it tends to lean out)
> 
> So, at WOT, the ECU ignores pretty much everything except rpm
> and maybe ambient air conditions?
> 
> It would follow, then, that only remapping the ECU will gain
> any improvement at WOT and high rpm, when you really care
> about maximizing power.
> 
> So all of this tweaking of the O2 sensor and AFM only has
> potential to help enrich the mixture at part throttle and
> relatively low rpm, correct?

Mike,
All this tweaking of the 02 sensor and AFM is a fool's way of blindly 
futzing with your car's air:fuel mixtures. In the same single digit IQ 
"mod" range as dumping arbitrary larger fuel injectors, arbitrary 
increasing fuel pressure level, swapping AFMs or screwing with their 
output. 
Depending on the year (and DME version), the ECU stores numerous (tens of) 
engine air:fuel:RPM maps depending on intake air temp, engine temp, full 
vs. part throttle, etc, etc, etc. 
Messing with one input might fool the DME into arbitrarily enriching the 
fuel mixture across _all_ of those maps. There is no way in hell it is 
beneficial for all of the maps under all of the conditions. 

Doesn't mean that some internet monkeys would not advise you to try these 
'free' mods.

> I'll stick with stock or a reprogrammed chip...

Amen, brother.

alex f

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