[Diy_efi] Re: Minimalist micro based EFI ?

[Mike]

mmmm fair enough Bill,

I took a close look at the hitachi ecu for my GMH with nissan
engine, the ECU is built by Bosch and has a thickfilm circuit
which hangs off the AFM input, it looks like a log to linear
with two outputs, plus what looks like an ECU controlled
floating reference - maybe this is an easy way to handle
the AFM 'no flow' at power up which can be from 1.2 to 1.7v

ie. Its as if it has a low range of 8 bits and an expanded
high end of any number of bits, given the attention to a
complex thick film circuit when 8 bit a/d's were around at
that time has me thinking the 8 bit processor was getting
rather more than 8 bits of air flow metering resolution...

rgds

mike



At 02:58 PM 3/11/03 -0000, you wrote:
>
>
>> -----Original Message-----
>> From: ext Mike [mailto:erazmus at iinet.net.au]
>> Sent: Tuesday, March 11, 2003 2:43 PM
>> To: List for general do-it-yourself EFI talk
>> Subject: RE: [Diy_efi] Re: Minimalist micro based EFI ?
>> 
>> 
>> At 02:28 PM 3/11/03 -0000, you wrote:
>> >For a minimalist system 8 bits is enough until you are 
>> running more than
>> 14PSI boost. 
>> 
>> <cough> I dont see how boost has anything to do with the 
>> number of bits.
>
>Everything. I had missed your MAF reference so I was talking MAP. But with
a 2.5 bar MAP sensor 8 bits is more than sufficient. Can't comment on MAF
other than GNs and sytys seemed to pass with a MAF sensor and 8 bit
processors and converters.
>
>> 
>> >There are plenty of megasquirts out there with 8 bit A/D and 
>> no problems.
>> 
>> Well sure and you could do it without any a/d just by using 
>> pulses from
>> the TPS however, there is the issue of emissions, so perhaps what i
>> should have asked/observed about was what is the accepted MAF 
>> resolution
>> for a tolerable emissions spread across load - in terms of what the
>> oem's do ?
>
>IF you want to meet ODB2 then you may need something more than mimimalist.
But if you want to meet 93 level emissions then 8 bits is fine.
>
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