[Diy_efi] Re: Minimalist micro based EFI ?

[Bernd Felsche]

On Wed, Mar 12, 2003 at 03:11:18PM +0800, Mike wrote:
> At 08:45 AM 3/12/03 +0800, you wrote:
> >On Tue, Mar 11, 2003 at 09:48:26PM +0800, Mike wrote:
> >> mmmm, I wondering now that 10 bits is just not enough,
> >
> >10 bits gives you 0.1% of FSD accuracy.
> 
> Not enough for log which is the majority of cars on road today,

I don't believe that a MAF's accuracy is that important, except at
or near idle; isn't that the reason for the log scale? When the
control loop closes, the errors in measurement will be compensated
in the same way as variations in conditions (e.g. O2 content,
humidity).

> >> The MAF signal is log with a DC offset of around 1.5v (which
> >
> >Which MAF? Pierburg are making MAFs with integrated digital hybrid
> >controller producing corrected and filtered output. Either PWM, CAN
> >or analogue. There's also an integrated intake air temperature
> >sensor.

> Well, I'm talking my car and the vast majority of aftermarket MAFs
> ostensibly for people who want larger throat sizes for more flow
> and have ECU's which accomodate these with retuning of course.

That makes the objective a little clearer. The amount of air is
directly proportional to the gross engine power; which could vary
from 10kW to 300kW in your case. Sure, the 10kW to 40kW is the
most-interesting in terms of emissions control, because that's the
typical cruising power requirement - given our low speed limits.

Anyway, is there a religious issue with programming log-airflow
tables?

> Eg. In the performance market for turbos for RB0 type engines,
> GTRs etc All of these are log output MAFs with a pretty similar
> DC offset and the same 5v max output - variety of fow rates
> and throat sizes...

> rgds
> 
> mike
> ps: put the supp cap in yet ? ;)

No... too hot and too busy.
> pps: Next time you are over I'd like to take a pic of your engine bay.

No big deal.

> ppps: Variety of beers cemented to back inside shelf of fridge ;)

-- 
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