Re: Urq poor cold start

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

In message <08c054629191898UPIMSSMTPUSR05@email.msn.com> "Ian J Haseltine" writes:

> Also checked for air leaks (just in
> case), dipstick stumble ok, if I compress and release the breather(?) tube
> (the 1" pipe that fits on the side of the air meter dome, the engine
> stumbles and sometimes stalls even though the ISV works like hell.

Dipstick stumble, I suggest, is really only a neat party trick and a
way of testing the dipstick seal.  You have a 'leaky' engine - there
is a considerable airflow through the breather tube.  This air is being
sucked into the engine through the crankshaft oil seals and the camshaft
seal - also the short rubber hose section that connects the main crankcase
breather that runs down the side of the engine has been known to rot at
the bottom.

Your last CO adjustments (or the last n adjustments, in fact) have
compensated for these leaks.  Breather airflow bypasses the air mass
sensor on the WR and MB, and so your fuel injection has been set to
over-richen to compensate for this air.  Clamp the breathers, and you
cut out this air - the engine then gets over-rich.

> >Pull the three grounds off the inlet manifold, sort out which one comes
> >directly from the coil, and 'rework' it.
> Three? Mine has only got two. Is there one missing? The one that broke is
> thinner gauge than the other and when I touch the bare wire on the manifold
> I can hear noises from the distributor.

Yes, there should be three on an MB.  A 2.5 mm and a 1.5 mm, both from
the ECU, and a 2.5 mm from the coil.

> Investigating around the coil, the light green cable (white tracer?) and the
> dark green cable that are in the multiplug connected to the black plastic
> cube shaped unit at the back of the coil are joined rather crudely to black
> cables in what appears to be an extra loom - alarm system maybe? There is
> also a short piece of black cable that terminates on the bracket that the
> wastegate valve fits on. This cable has been cut and I cant find the other
> end (if it still exists) is this standard Audi? (cable termination looks
> OE).

Green/white is the ECU driver signal.  Black is volts.  Red and blue
drive the coil primary.  Green from the coil primary goes to a
diagnostic connector not used in the UK.

> The engine stalled a couple of times last week, both at low speed but
> restarted without problems. Started happening a day or two after I'd had the
> ECU disconnected so I could work in the drivers footwell - possible
> connection? l think that I'll check it out just in case.

Did you find anything?

--
 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
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