Injector control

[Greg Hermann]

>-----Original Message-----
>From: Greg Hermann <bearbvd at sni.net>
>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>Date: Wednesday, November 25, 1998 9:52 AM
>Subject: Re: Injector control
>
>
>>>bearbvd at sni.net (Greg Hermann) wrote:
>>>> First--has anybody figured out how small an incremental adjustment to
>>>> injector pulse width time the OEM ecm's are capable of making (GM,
>Bosch,
>>>> etc.???)?? If so, is it posted anywhere??
>>>
>>>GM is 1/65536 or 1/65517 of a second.  So, about 15 microseconds.
>>>
>>Thanks, Ludis. To me, this means that, if trying to use a GM unit in a real
>>hipo application, NO WONDER it is tough to get a particularly good idle!!
>
>Is it that, or MAP/MAF filtering at idle, that is the problem?.
>Or is it a combination of idle speed/MAP/MAF flucuations causing
>the ecm to glance at a near table that at fault?.
>By the way, what would you call good enough resolution?.
>Bruce

To do a really good job of getting an idle JUST RIGHT-- my WAG (but a
fairly well educated one) would be that you want to be able to adjust the
amount of fuel delivered at idle in no more than 1% increments, I would be
happier with 1/3% adjustment capability. This is based on considering that
a 1% change in fuel delivered equates to about a 0.14 change in a/f ratio
and a 1/3% change would equate to a 0.05 adjustment to a/f ratio.
>>
>>Regards, Greg
>>
>>