How do AICs work?

[Bruce Plecan]

-----Original Message-----
From: Daniel Houlton <houlster at user2.inficad.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Friday, March 05, 1999 10:04 AM
Subject: Re: How do AICs work?

While it's common practice not to exceed 85%, if your oem calibration does,
what makes you believe that for that application 100% is wrong?.
  You mention smog police, and steathy, ya really think they'll miss the
turbo?.
Did you ever figure out for sure if the MAF is voltage or freq?.
Bruce
>soren wrote:
>>
>> >If I need to intercept and modify the MAF signal anyways, then I'd much
>> >rather swap to larger injectors than run the rising rate FPR or plumb in
>> >additional injectors.  It's much cleaner I think, doesn't have any bad
>> >sides that I can see (so long as I don't go so big it won't idle) and
>> >it's much more stealthy.  I'll have a much better chance of sliding this
>> >whole thing by the smog police if I don't have a huge regulator or extra
>> >fuel lines and injectors running everywhere.
>> >
>> >Any insight is appreciated.
>>
>>
>>     I definitely agree that larger injectors are the way to go depending
on
>> your budget.  The lack of extra plumbing is definitely a plus.  However,
if
>> the ECM is reacting to the extra boost and going to 100% duty cycle on
the
>> stock injectors but cannot react to the change in fuel mixture caused by
an
>> additional injector (because it is in open loop), how could it react to
the
>> change in fuel mixture caused by the larger injectors when the ECM
commanded
>> 100% d.c.(again in open-loop)?  It appears to me as if they would be
similar
>> in actual function.
>>
>> Soren Rounds
>
>
>Regardless of how the extra fuel is added, the idea is to keep the ECM from
>commanding 100% d.c. by intercepting the MAF signal, changing (reducing)
it,
>and then passing it on to the ECM.  How much to reduce it is the tricky
part
>as the MAF output is not linear to the airflow through it.
>
>In the case of the addition injector or higher fuel pressure, I'd have to
>figure houw much to reduce the MAF signal based on how much extra fuel the
>higher pressure or extra injectors will dump.  i.e. if the extra injectors
are
>dumping 30% of the total fuel, the MAF signal to the ECM would have to be
>reduced enough such that the ECM injects 30% less fuel.
>
>With larger injectors that flow say 50% more fuel than stock, the MAF
signal
>would need to be reduced enough so that the ECM would inject only 66% of
the
>fuel it would of from the un-modified signal.
>
>When it's in open-loop WOT, it reads the MAF directly and squirts an
appropriate
>amount of fuel.  The extra fuel from having larger injectors is offset by a
>shorter pulsewidth (and therefore duty cycle) commanded by the ECM from
seeing
>a lower signal from the MAF.
>
>
>--Dan
>