[Diy_efi] And for the bottom end of the market....
David
d_cottrill at iprimus.com.au
Sat Jun 14 02:00:12 GMT 2003
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Hello all, My MR2 ( 1988, jap import supercharged 1.6lt (standard)) has
had its ecu die, sort of. My mechanic tells me the ecu has decided the
engine isn't there after the engine swap even though it still uses the
original sensors which all give the correct readings.
To remedy the situation I'm getting to work on a fuel injection system
for my postie bike ( Honda CT 110 for those outside Australia) which has
no complications other than a maximum alternator output of 7A (not quite
enough to run all the lights at the same time) and having to mount
everything externally. Other than that it sports one cylinder with a
whopping 110cc capacity, electronic ignition and a 4 speed manual up to
a maximum speed of 80kmph on flat ground (~ 50mph). The idea to
implement it one module per cylinder on the car later, once I've got it
all sorted out
Seeing as I'm largely ignorant of all sorts of things I'm starting with
as few inputs as possible so I'm still trying to figure out how many
sensors I can make do with for the efi. At the moment only manifold
vacuum and idle switch,
not sure if I have to use throttle postion as well....
This is the high level code at the moment, suggestions?
Injector time = idle time + ((max time @ inlet vacuum) * throttle %)
OR
Injector time = idle time + (time @ inlet vacuum)
Injector time is how long the injector fires per induction cycle.
Idle time is how long it has to fire for a reasonable idle. (minimum
throttle)
Max time is the amount of fuel I can put in the engine for maximum power
for that amount of air.
time @ inlet vacuum same as above but calibrated without throttle input.
Inlet vacuum will be measured after the throttle body so I may not need
a throttle sensor.
At the moment I'm just trying to emulate the carburettor so if I can
just use a reference array instead of having to compute everything that
would seem to make everything much simpler. Tuning is going to be a
trial and error situation as my workhop is about as complete as any
other chef (this will change in time).
Other sensors to come later: engine temp, exhaust oxygen, tacho, knock
sensor.
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<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial size=3D2>Hello =
all, My MR2 (=20
1988, jap import supercharged 1.6lt (standard)) has had its ecu die, =
sort of. My=20
mechanic tells me the ecu has decided the engine isn't there after the =
engine=20
swap even though it still uses the original sensors which all give the =
correct=20
readings.</FONT></SPAN></DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial=20
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial size=3D2>To =
remedy the=20
situation I'm getting to work on a fuel injection system for my postie =
bike (=20
Honda CT 110 for those outside Australia) which has no complications =
other than=20
a maximum alternator output of 7A (not quite enough to run all the =
lights at the=20
same time) and having to mount everything externally. Other than that it =
sports=20
one cylinder with a whopping 110cc capacity, electronic ignition =
and a 4=20
speed manual up to a maximum speed of 80kmph on flat ground (~ 50mph). =
The idea=20
to implement it one module per cylinder on the car later, once =
I've=20
got it all sorted out</FONT></SPAN></DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial=20
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial size=3D2>Seeing =
as I'm=20
largely ignorant of all sorts of things I'm starting with as few inputs =
as=20
possible so I'm still trying to figure out how many sensors I can =
make do=20
with for the efi. At the moment only manifold vacuum and idle =
switch,<BR>not=20
sure if I have to use throttle postion as well.... </FONT></SPAN></DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial =
size=3D2></FONT></SPAN><FONT=20
face=3DArial size=3D2></FONT> </DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial size=3D2>This =
is the high=20
level code at the moment, suggestions?<BR>Injector time =3D idle time + =
((max time=20
@ inlet vacuum) * throttle %)<BR>OR<BR>Injector time =3D idle time + =
(time @ inlet=20
vacuum)</FONT></SPAN></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial =
size=3D2>Injector time is how=20
long the injector fires per induction cycle.<BR>Idle time is how long it =
has to=20
fire for a reasonable idle. (minimum<BR>throttle)<BR>Max time is the =
amount of=20
fuel I can put in the engine for maximum power<BR>for that amount of=20
air.<BR>time @ inlet vacuum same as above but calibrated without =
throttle=20
input.<BR>Inlet vacuum will be measured after the throttle body so I may =
not=20
need<BR>a throttle sensor.</FONT></SPAN></DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial=20
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial size=3D2>At the =
moment I'm=20
just trying to emulate the carburettor so if I can just use a =
reference=20
array instead of having to compute everything that would seem to make =
everything=20
much simpler. Tuning is going to be a trial and error situation as my =
workhop is=20
about as complete as any other chef (this will change in=20
time).</FONT></SPAN></DIV>
<DIV><SPAN class=3D190493001-14062003><FONT face=3DArial =
size=3D2><BR>Other sensors to=20
come later: engine temp, exhaust oxygen, tacho,=20
knock<BR>sensor.<BR></DIV></FONT></SPAN></BODY></HTML>
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