AW: DIY_EFI Digest V5 #909

[Ludis Langens]

Jens Knickmeyer wrote:
> 
> I recognized that the ECU sometimes tells a value of 1.85V. AFAIK, lambda
> voltage
> is limited by approx. [0.1V, 0.85V]. I tried to recognize any correlation
> between lambda voltage and any other signal, but I couldn't. The 1.85V
> occurr instead of the 0.85V I would have expected. The "lean" voltage of
> 0.1V is reached in every cycle, no problem there.

The 1.xx volts might be a data communication error:  If the value is
sent as two bytes, it could be that the value changes between the time
that the high and low bytes are sampled by the diagnostic interface. 
Thinking in decimal, perhaps the voltage was 1.01 volts.*  The interface
sends the 1. part.  Meanwhile, the voltage drops to 0.85.  The interface
then grabs the .85 part.  Presto, your logger says 1.85.  Early GM ECMs
had this problem - it was corrected in the late 1980's.

* Yes, that's a possible voltage.  I have a carb'ed truck that likes to
idle at say 1.08 volts.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/


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