Benching Ecms

[Bruce Plecan]

-----Original Message-----
From: goflo at pacbell.net <goflo at pacbell.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Wednesday, July 29, 1998 10:53 PM
Subject: Re: Benching Ecms

Slowly I'm starting to get this,

How can one tell what a devise can source?.

I got such cunfusin measurements from a MAP I broke it apart,
and found some dodads in it so it wasn't a resistive devise.  But,
the TPS was and as I recall had like 6K resistance, so I used a 5K
pot.  If I do the same with 1K+5K, and 10K+50K and get the same
outputs would using the higher be better?.
TIA
Bruce


>Not clear from description how you are rigging the map input to the ecm.
>For 0-5V approx you need a voltage divider across the voltage source.
>
>
>*          R1           pot
>5V ------/\/\/\-----/\/\/\/\/\------ground
>                         |
>                         |__________ to ecm map input
>
>R1 is for current limiting. If your 5v source can source 5 ma then
>use 1k for R1 and your 5K pot. If not increase R1 to 10K and use a
>50K pot.
>
>Regards, Jack
>
>Bruce Plecan wrote:
>>
>> Finally applied power to the bench ecm project today, and all seems
>> good and well so far.  Upon reflection I want to run something past the
>> folks that have already done this, is using a 5K pot OK for the MAP,
>> and TPS??..
>>     The reason I ask is that with the MAP twisted to high and with a
>> 1K ohm resistor in line, I still get a MAP voltage of 5.1volts.  Should I
>> increase the value of the "limiting" resistor?.
>>     I also used a 470 ohm resistor thinking that would keep the min
>> TPS to about .5volts, but it's .18volts.
>>     What's the error in my thinking here.
>> TIA
>> Bruce          Ya shoulda seen the staff run when I yelled "Fire in the
>>                     Hole", when I flipped the main switch on.
>
>