[W126 Coupe] Cold Start Valve & Engine Temp Sensor Question

[Dick Spellman]

Hi Talbir:

You've just described the unit on my 86 300SE Euro which is two single wire
connections.  The 1990 is a 4-pin round connector.  But, the operation must
be very much the same.  And yes I noted when trying to figure out what size
socket that my largest a 21 didn't quite fit.

But, to the issue of constant cold start valve operation, your description
suggests that once a specified temperature is reached, some # of seconds
later the circuit 'opens' switching off the cold start valve.  So, if my
sensor is showing always closed it's a good bet the cold start valve is
always lit, so to speak.  Which is what my crude tests showed today.

So, I'll go ahead and replace the unit and run the test once again to see if
in fact it solves the problem of a hard start and I'm going to bet it will
improve the gas mileage.  I think I'm changing the oil now as well if the
system has been getting all this extra fuel.

Thanks,
Dick