Problems with EFI car idle and pressure sensors
David Sackett
david.sackett at optusnet.com.au
Fri Sep 21 08:05:32 GMT 2001
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Thanks for all the suggestions, I'll try using a MAP sensor in =
conjunction with the original TPS (and triple check my ignition timing =
however, the car ran fine on carbies and i haven't touched the ignition =
system).
The original TPS has a WOT switch, an idle switch, an acceleration =
switch, a deceleration switch and a switch that turns on and off with =
change of position. this should give me all I need for acceleration =
inrichment.
also, how should the computer handle the idle situation, should the =
lookup table go from idle vacuum to atm pressure or should the idle =
switch be used to fix the idle open time?
Surely the second option would defeat the purpose of having a MAP sensor =
to correct my idle problem.
Here are the answers to the extra questions posed by Bernd Felsche =
<bernie at innovative.iinet.net.au>
>You're using D-jet. injectors?
yes I am using the original injectors and have checked that they all =
produce the same volume of fuel after cranking the engine for a while. =
the spray pattern is a clean cone shape and I have checked that fuel =
pressure is constant at 28psi. Also i am only using a mosfet transistor =
to open them so perhaps i need peak and hold.
>What are you using as a time base? Camshaft or distributor sensor?
I'm not sure what this means but the injector open time is accurate to =
0.05msec. All injectors fire from the distributor switches, both of =
which produce a rising edge once per revolution of the distributor (or =
crank). the two switches operate exactly out of phase.
>Is the distributor _static_ or does it have variable advance?
the switches for the efi are below the normal advance mechanism that =
operates the ignition. These switches are therefore static despite the =
ignition advance.
>Do you have idle and WOT switches as well?
I currently don't have these switches but the computer knows when the =
engine is at idle or WOT because my PC tuning software allows TPS =
calibration when the engine is not running.
>Are you controlling ignition timing as well?
no, I am not controlling ignition timing.
thanks again
David
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<DIV><FONT face=3DArial size=3D2>Thanks for all the suggestions, I'll =
try using a=20
MAP sensor in conjunction with the original TPS (and triple check my =
ignition=20
timing however, the car ran fine on carbies and i haven't touched the =
ignition=20
system).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The original TPS has a WOT switch, an =
idle switch,=20
an acceleration switch, a deceleration switch and a switch that turns on =
and off=20
with change of position. this should give me all I need for acceleration =
inrichment.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>also, how should the computer handle =
the idle=20
situation, should the lookup table go from idle vacuum to atm pressure =
or should=20
the idle switch be used to fix the idle open time?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Surely the second option would defeat =
the purpose=20
of having a MAP sensor to correct my idle problem.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Here are the answers to the extra =
questions posed=20
by Bernd Felsche <<A=20
href=3D"mailto:bernie at innovative.iinet.net.au">bernie at innovative.iinet.ne=
t.au</A>><BR><BR>>You're=20
using D-jet. injectors?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>yes I am using the original injectors =
and have=20
checked that they all produce the same volume of fuel after cranking the =
engine=20
for a while. the spray pattern is a clean cone shape and I have checked =
that=20
fuel pressure is constant at 28psi. Also i am only using a mosfet =
transistor to=20
open them so perhaps i need peak and hold.<BR><BR>>What are you using =
as a=20
time base? Camshaft or distributor sensor?<BR></FONT><FONT face=3DArial =
size=3D2>I'm=20
not sure what this means but the injector open time is accurate to =
0.05msec. All=20
injectors fire from the distributor switches, both of which produce =
a=20
rising edge once per revolution of the distributor (or crank). =
the two=20
switches operate exactly out of phase.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>>Is the distributor _static_ or does =
it have=20
variable advance?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>the switches for the efi are below the =
normal=20
advance mechanism that operates the ignition. These switches are =
therefore=20
static despite the ignition advance.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><BR>>Do you have idle and WOT =
switches as=20
well?<BR>I currently don't have these switches but the computer knows =
when the=20
engine is at idle or WOT because my PC tuning software allows TPS =
calibration=20
when the engine is not running.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>>Are you controlling ignition timing =
as=20
well?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>no, I am not controlling ignition=20
timing.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>thanks again</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>David</DIV></FONT></BODY></HTML>
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