[Diy_efi] Re: EMS inputs/output?

[huw scourfield]

for lambda to work - (at least a narrow band sensor, a wideband is totally
different), the ecu constantly - at the rate of around once or twice a
second - sends the mixture rich/lean. The lambda sees this as a square-wave
with varying mark-space ratio, the electronics then does some maths and
signals rich or lean and compensates accordingly. This compensation is an
adjustment of the "mapped" or pre-calculated fuelling - the open loop
fuelling. The reason for this is that a std lambda is a narrow band
instrument that only really works around stoichiometric, a wideband lambda
can work over a wider range and thus would not need the alternating mixture.
    Ping sensors can be very simple accoustic sensors, but to filter out
unwanted noise a complicated dsp chip is usually used, this is normally
"gated" with the ignition signal to ascertain which cylinder is pinging, a
project on it's own I'd say!
    Dwell is the time the coil is charged by the battery, it is normally
longer at cranking or low battery voltages and is controlled electronically
to prevent overheating the coil at low engine speeds.
    Huw
----- Original Message -----
From: "alex averbuch" <averchoob at hotmail.com>
To: <diy_efi at diy-efi.org>
Sent: Thursday, July 25, 2002 5:52 AM
Subject: [Diy_efi] Re: EMS inputs/output?


> Cheers for the help Huw
> Is the difference between open and closed loop just the ommission of the
> LAMBDA sensor or is there more to it?  If it is then wouldn't a closed
loop
> method just continuosly poll the LAMBDA for changes and
increment/decrement
> the inj-open-time accordingly?
>
> What complications would a Ping sensor introduce if I wanted to use it as
> one of the inputs for the ECU? Isn't it simply an anolog input from a
> microphone,where a frequency (or volume?) over a certain threshold would
> signal that detonation is occuring, or do other problems like calibration
> nightmares also come into play?
>
> This is probably a dumb question but what is Dwell? you mentiond it but
I've
> never heard that term before.
>
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