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Re: 3.9k Ohm Diagnostic mode on a P4.



On Sun, 27 Aug 2000 11:35:58 -0800, Ludis Langens <ludis@cruzers.com>
wrote:

>Bruce Plecan wrote:
>> 
>> Then for a while this was the mode that when done on the assembly line, that
>> the EPA demanded that the car be recorded in.  What the policy is now for
>> the new car recordings is now I haven't a clue.
>
>That's strange!  AFAIK, only GM has an analog limp home mode.

I'm still a little confused by this term above "analog limp home
mode". Is there infact some analog fueling and INJ firing taking
place, or is this mode simply a way for the ecm to revert to analog
defaults if it's *sensor* base goes awry? Reason I'm asking is that
some previous posts suggested that fueling would still continue even
if the memory storing the ecm code had failed. I'm puzzled as to how
this would be possible, since the ecm fires the INJs, both timing-wise
*and* driver-wise.

I guess what I'm asking is: what is the extent to which the ECM is
able to fail and still have the INJs fire. Mind you, I'm OK with and
presume that the IGN would continue on without ecm intervention/EST,
via it's own autonimous module; but I'm unclear as to where the INJ
timing/firing is going to come from, if the ECM fails to the point
where it can't execute code anymore. This currently dudn't make sense
to me.

TIA,
Gar


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