EEC-IV Questions

[Brian Warburton, c/o Turbo Systems Ltd]

>
>As stated above, I've tried to diagnose the vehicle using the internal 
>diagnostics, but I get no reply.  The vehicle appears to be running in 
>"limp home" mode, and the sensors I've checked look okay (It's pretty 
>tight in an Escort's engine compartment)
>
> Corey Cole                                    colec at pr.erau.edu

Can't say for sure about the very latest Ford modules, but up until
I left Ford of Britain in December 1994, the standard way to
determine if you were running in LOS (limp-home mode) was to
monitor the fuel pump with the ignition on before engaging crank. 
The EEC-iv s/w used to keep the pump on for 1 second after key-on
without detecting rotation before turning it off. In LOS, the pump
was switched on all the time the ignition was on.

>From my experience, the only thing that made the module run LOS was
the EEC-iv s/w failing to kick the LOS "watchdog". This implied a
serious software bug causing the s/w to get "lost" (unlikely in a
production module) or an electrical fault stopping the processor
from executing the s/w. To the best of my knowledge, there were no
sensor and/or actuator failures that would cause this condition.

It may be time to dust off the logic-analyser ............

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian Warburton,   "Still searching for the perfect curve....."
email: bwarb at turbo.win-uk.net
                               Advanced Automotive Electronics Ltd,
                               Van-Nuys House, Scotlands Drive,
                               Farnham Common, England.  SL2-3ES
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