Bench ecms

[Bruce Plecan]

-----Original Message-----
From: peter paul fenske <ffnsp955 at bcit.bc.ca>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Thursday, August 06, 1998 9:13 PM
Subject: Re: Bench ecms


Geez, makes perfect sense.
Thanks
Bruce


>Dear Bruce
>
>You have to look at ground analysis.
>With no current draw from accessories engine starter ect
>eng ground is ecm ground.
>Turn something on and engine ground might measure -3volts
>which is evil in ecm terms.
>
>Also signal noise analysis.
>An improper ground would let noise into the ecm.
>
>Thus sensor ground shall always be used for sensors, O2 gnd fer
>O2, and power ground for power ground, as well as injector returns
>should go to back of engine block
>
>Have a gun one.
>
>:peter
>
>At 07:29 PM 8/6/98 -0400, you wrote:
>>I had been told the sensor grounds on a gm ecm floated in reference to the
>>chassis ground, well that doesn't appear to be correct, everything is just
a
>>couple tenths of an ohm from true ground.
>>With no displayed voltage drops across grounds.
>>While still seperated, does it really matter if sensor grounds go to
>>chassis, on an actual car?.    If so then where Have I strayed to having
>>had sensor ground problems????....
>>
>>
>>For coolant temp, and intake air temps, I was just going to share
>>resistances.  Tieing grounds together.
>>
>>For TPS, and MAP I was going to tie the grounds together, use the
>>+5 from one ecm, and then share the sensor's output.
>>YES/NO??????..
>>
>>Cheers
>>Bruce        RPM signals applied to both ecms, and powered up
>>                  leds flashed and no problems today.
>>                  The cat has grown boarded with the flashing LEDs,
>>                  but the staff is acting like their inna stupor.
>>
>>
>>
>
>