[T3] running rich and mystery material

Dave Hall dave at hallvw.clara.co.uk
Sat Nov 10 03:30:49 PST 2012


It looks as if you have a very rich mixture. Are you sure the pressure
sensor hose is in place and not leaking?  
In your earlier video everything seemed to be working when driving around
the school grounds.  Was that only after it had warmed up?   If that was
from cold, something has changed dramatically - a lead off, a hose leaking
maybe. 

Try taking the hose off the AAR - the idle should rise.  A thumb over the
end to stop the air bleed into the IAD should drop it again.  If it doesn't
behave like that, it's probably not the AAR.  Conversely, if the thumb
controls the fast idle speed OK, the AAR may be stuck shut.

However, a faulty AAR won't make the mixture richer.  It only controls the
fast idle speed, by reducing manifold vacuum which lets more air and hence
fuel into the cylinders.  

The cylinder head temperature sensor tells the brain to enrichen the mixture
during warm up.  Maybe that's detached and therefore giving an infinite
resistance.


Dave.
UK VW Type 3&4 Club
===================-+


-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Dennis
Stiefel
Sent: 10 November 2012 03:11
To: type3 at vwtype3.org
Subject: Re: [T3] running rich and mystery material




Hello Dennis. As far as your running rich issue - I would agree with
Adriel's comments;

 

-          Check the cold and warm resistance on your 2 temp. sensors. If
they are not sending the correct resistance to the brain, then the brain
will think you are running hotter or colder that it really is..maybe
creating a too rich mixture for the real operating temp. of the motor.

 

-          Is certainly sounds like your AAR is not working because you have
no increased idle speed when cold. It is not supposed  a large increase in
cold idle speed, but it will be higher than when the motor is warm. The
brain is supposed to make the mixture a little richer when cold (like a
choke on a carbed car), and the AAR is supposed to supply extra air into the
IAR that will provide more air to the cylinders when the motor is cold and
the mixture is richer. The extra air combined with the richer mixture
results in a higher than normal idle speed. Your video shows no indication
that your idle speed is compensated for when this richer mixture occurs when
cold.

 

 

Dave Pallo

'72 Square ~ Elwood

Fairport, NY

 

Well I just got the number 2 temp sensor from Jim because I miss placed the
one I had.  Of course I found it after Jim sent it so I can just put the
other one in and see if there is any difference.  I checked the AAR before I
installed it during engine assembly.  The spring turn freely and moved with
the shaft it is hooked up to. I tried blowing through it and when I would
turned the spring I couldn't and then when I released it I could blow
through it.   Was there anything else I needed to check on it?

Dennis 

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