Slow start when cold.
 

My W124 300E takes too many seconds to start from cold.
-- like 10-15 seconds on one start. :(

I can't get to the bottom of it.

I have replaced the sparks, ht leads, rotar arm and dist cap.
Also, I have change the oil.

When it is cold, I have checked for sparks at the plug end, and that's fine - sparking straight away.

I have tried the pre-start fuel trick several times (turning the key to '2' a few times before starting the car) - this makes no difference.

So I am looking for inspiration?? Can you help.
I thought next was perhaps vacumn hoses..? - how can I check these.

Any other ideas gratefully accepted. ..

Turrning the key 2 or 20 times before starting has the same effect on your problem then closing your door 5 times before starting....none.
Possible causes:
Cold start valve
Fuel pump
Clogged fuel filter.
Fuel pressure regulator.
Ignition system,
Bad case of low engine compression.
Vacuum leaks
JackD

How cold is it where you are? How old is your car?
You might have bad connection to the coolant temp sensor.
Have you measured the voltage or duty cycle on pin 3 of the diagnostic port?

The fuel pump I pressume is working since it makes the right whurring noise and I can drive around okay once started.
The fuel filter I will change this weekend (ordered new part last Friday)
Any suggestions on how I can check the Cold start valve, Fuel Pressure Regulator and vacumn leaks?

Its not the cold itself, its significant whenever it hasn't been started for a while.

What's this pin 3 diag port stuff... how do I do that then?