re: Hot Starts

["Evans, Tom" <tevans@domain.elided>]

Joe,

Thanks for the correction on the Auxilliary Air Device.  You are totally
correct that it works on metered air and only affects idle speed.  I think I
was on my third scotch at the time I wrote that.

I only suggested the AAD as a possible contributing factor because I had
some warm start trouble before I freed up a sticking plate inside the unit.
If the AAD is sticking closed during a cold-start, the idle may drop to the
point the engine dies.  If your idle speed is set too low to begin with,
this may cause a starting problem as it did in my car.  I think when the car
cooled down overnight, the bi-metallic actuator was able to overcome the
sticking plates and open up the bypass.  

I'm not sure I agree with your theory on the cold start valve.  The cold
start valve always comes into play when the coolant temperature is below 86
F (The service manual says the switchover range is between 86 and 104).
Your theory was that the cold start valve was firing when it shouldn't and
flooding the engine.  Is it possible that the cold start valve is not firing
when it should on a recently cooled down engine?  I think it depends on the
engine temp at the time.  But I do think the cold start valve is necessary
even in moderate climates.  

Thinking along the lines of temperature, there are other possible culprits.
The engine needs substantial fuel enrichment during it's warm-up phase.  If
the Bosch fuel computer thinks the engine is warmer than it is, a
hard-starting situation could occur.  The air temp sensor in the AFM and the
coolant temp sensor can be tested to check for this happening.

Do you agree that it sounds like the engine is not getting enough fuel under
this hard-starting condition?

-Tom
'86 Spider

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