Field Service Mode

[Mark Romans]

If I remember correctly, Field Service Mode, goes to a fixed timing and
really rich fuel. So it probably wouldn't ping in Field Service Mode, you'll
also foul your cat conv and probably just not run that great.  But it is a
LOT better than tennis shoe mode.
Mark
-----Original Message-----
From: David Mulvey <kd6bzn at QNET.COM>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Saturday, July 31, 1999 4:18 PM
Subject: Field Service Mode


My 87 IROC 5.0 has a ping problem when I get on it hard. Error codes light
up indicating a bad MAF or MAF relays or wires inbetween.
I tested and cleaned and check all componants best I know how.  Everything
seemed OK.  MAF gives a voltage of .7 Volts at idle, and
when I gas it in the driveway it jumps to about 2 Volts. It's got a new
block.

One thing that I don't understand is why does my car run perfect with no
pinging with the ECM in Field Service Mode (Pins A and B
shorted)?  Should I leave it in Field Service Mode?  Does the computer take
sensors out of line in this mode and then somehow keeps
the car running through a backup mode???

I am currently working on a diagnostic hookup so that I can fit right in on
this list, hopefully that too will help out. I will be
sure to post on my web site any software that I may develope.  Thinking of
realtime window based displays of what ever word I would
like to look at.  I have been doing this sort of thing at work on Military
Aircraft, but this will be my own time, equipment, and
serial based instead of 1553 bus.

Thanks

David
Lancaster, CA