[W126 Coupe] Cold Start Problem

[Sharan Bains]

Henry,

You'll see the cold start injector (CSI) right in front of the air filter, 
near the idle air valve.

It has one metal fuel line coming onto it and has a green/blue plug 
protruding from the side with a black loom coming into it.

The loom connecting to the green plug can be removed by slipping off the 
metal retaining clip which slots round the loom connector.

Using a 5mm allen key, remove the two 5mm allen bolts holding down the 
injector onto the inlet manifold. Leave the fuel line connected to the 
injector.


Lift out the injector and having removed the loom connecting to it, attach a 
ground and +12V to the two pins on the injector. It should spray out fuel.

(Of course, take safety precautions as fuel may be sprayed - ensure engine 
is switched off)

If it does not, then you have a faulty cold start injector.

Second test - with car stone cold, leave fuel line and loom connected to 
cold start injector, but lift injector out of manifold slightly and place it 
into a small plastic cup. Then turn engine for a few seconds. You should 
find that there is a small amount of fuel in cup.

If not, then cold start sensor is likely faulty. This is the 4 pole switch 
on the manifold. It can be checked for resistance values....Chet is the man 
for the values you should be reading here.

Check integrity of loom coming into CSI.

Other reasons for your hard cold starting - bad injectors (clogged or 
leaky), wrong spark plug spec, faulty fuel pressure regulator (the one on 
the side of the fuel dist). Your idle air valve maybe sticky too. Check the 
air metering plate too for absolute clearance from intake walls.

talbir





>From: "Henry Viveiros" <henryviv@grantspass.net>
>Reply-To: mbcoupes@mbcoupes.com
>To: "Mbcoupes@Mbcoupes. Com" <mbcoupes@mbcoupes.com>
>Subject: [W126 Coupe] Cold Start Problem
>Date: Sat, 1 Jan 2005 12:05:17 -0800
>
>My 1991 560 SEC starts fine when the weather is mild (above 50 degrees).
>When the outside temperature is less than that it starts and instantly
>stops. It will start the second time I try it. It was this way last season,
>was OK during the summer, and now that the weather has become cool again, 
>it
>is doing the same thing again.
>
>I think I have read something about the Cold Start Valve. Where is it? What
>does it look like? What can I do to check it?
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