[Diy_efi] WOT tuning tool

Karl Walter krw at efn.org
Thu Feb 17 23:45:55 GMT 2005


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OK, I found the signal in the ECU that runs the two injector drivers.  =
On the scope it's a nice square wave, varying in duty cycle with the =
throttle position on my bench test.  SO...  The power commanders are =
$300 and might not work.  The kit from jayco as far as I can tell, needs =
tuned by laptop.  I would like  keep things as simple as possible and  =
analog, and just have a pot to turn.  Something you can do while =
driving.  Here's what I am thinking:  Pulse from ECU ----> pulse width =
to voltage circuit ---> amplify/attenuate circuit with pot --->voltage =
to pulse width circuit.

The  amplify/attenuate could be done with an op amp, and there is a =
really simple 555 v to pulsewidth ckt I've used in the past, So I just =
have to find a pulse width to voltage ckt. Any thoughts there?  Part of =
a pulse width monitor maybe?=20

I made a vss calibrator this way, and it worked well, but it used a =
frequency to voltage circuit instead of a pulse width to voltage.=20

The wide band tuning method,(I'm asking) this would entail doing runs =
and datalogging the mixture, rpm, tps, then using this info to set the =
wot parameters in the ecu, correct?  For me the problem with that is =
that if the parameters are way far off, it takes a bunch of runs just to =
get in the ball park.  I like to have helpers to the test drives, as I =
need to mind the shop.  It's easy for them to go out with something =
running really lean and do it in, or foul plugs and be stranded.  If =
they had a quick way to correct the mixture, then the run could be much =
more effictive and less destructive.  How little could a wb setup run, =
say a kit, software and cables, and the o2 sensor itself? $200?



--Karl
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<DIV><FONT face=3DArial size=3D2>OK, I found the signal in the ECU that =
runs the two=20
injector drivers.&nbsp; On the scope it's a nice square wave, varying in =
duty=20
cycle with the throttle position on my bench test.&nbsp; SO...&nbsp; The =
power=20
commanders are $300 and&nbsp;might&nbsp;not work.&nbsp; The kit from=20
jayco&nbsp;as far as I can tell, needs tuned by laptop.&nbsp; I would =
like&nbsp;=20
keep things&nbsp;as simple as possible and &nbsp;analog, and just have a =
pot to=20
turn.&nbsp; Something you can do while driving.&nbsp; Here's what I am=20
thinking:&nbsp; Pulse from ECU ----&gt; pulse width to voltage circuit =
---&gt;=20
amplify/attenuate circuit with pot ---&gt;voltage to pulse width=20
circuit.</FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>The&nbsp; amplify/attenuate could be =
done with an=20
op amp, and there is a really simple 555 v to pulsewidth ckt I've used =
in the=20
past, So I just have to find a pulse width to voltage ckt. Any thoughts=20
there?&nbsp; Part of a pulse width monitor maybe? </FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>I made a vss calibrator this way, and =
it worked=20
well, but it used a frequency to voltage circuit instead of a pulse =
width to=20
voltage. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>The wide band tuning method,(I'm =
asking) this would=20
entail doing runs and datalogging the mixture, rpm, tps, then using this =
info to=20
set the wot parameters in the ecu, correct?&nbsp; For me the problem =
with that=20
is that if the parameters are way far off, it takes a bunch of runs just =
to get=20
in the ball park.&nbsp; I like to have helpers to the test drives, as I =
need to=20
mind the shop.&nbsp; It's easy for them to go out with something running =
really=20
lean and do it in, or foul plugs and be stranded.&nbsp; If they had a =
quick way=20
to correct the mixture, then the run could be much more effictive and =
less=20
destructive.&nbsp; How little could a wb setup run, say a kit, software =
and=20
cables, and the o2 sensor itself? $200?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>--Karl</FONT></DIV></BODY></HTML>

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