WOT switch

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <01BCFCD8.D29EF6E0@pm3-1-34.connectcorp.net> The Shadow writes:

> If yours is truly one of the european versions it is very different from  
> the USA version.

No, they're identical.  The only difference in WOT switches is the mid-1908s 
change from a dual microswitch arrangement to the integrated unit.

> The throttle switch may only activate the solenoid on the firewall that  
> bypasses the warm up air valve on the head to provide fuel enrichment under
> boost and cold running.  Boost is not controlled by the throttle switch 
> like it is here.

There are four engine states:
 
1) Off (for the pedants among us)
 
2) Idling
 
3) Cruising (for want of a better word)
 
4) WOT (wide open throttle - a misnomer)
 
The first is irrelevant.  The second is indicated by the idle microswitch 
(throttle closed) and causes the idle controller to optimise engine performance 
primarily to avoid vibration.  There are secondary inputs for low battery 
voltage and vehicle motion, when a higher idle may be selected.  The third 
state differs not between North America and Europe, but between vehicles fitted 
with emission controls and those that are not.  In emission-controlled 
vehicles, the ECU maintains a servo loop using the oxygen sensor and the fuel 
frequency valve.  In non-controlled vehicles, it uses a table-based 
calculation.  The fourth state is fundamentally the same for all vehicles, 
since attempts to optimise for low emissions are abandoned at WOT.

Boost is a separate issue.  European vehicles corresponding to the MC-2 (the MB 
and 1B engines, primarily) use ECU control of boost at WOT just as North 
American vehicles do.  Scott Mockry has come up with a wonderful little test 
lead for showing this in operation.  The WR engine, in both its North American 
and all European forms, uses only mechanical boost controls.

I don't know the JY engine, but I strongly suspect it's a variant of the 1B 
especially for Switzerland.  In this case only the third state is different 
from a North American MC-2 engine.  

> If your switch has 100 ohms resistance you are missing out on the added  
> fuel enrichment.

Yup.  100 ohms is a bust switch.
  
-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club