[T3] (no subject)

[Dave Hall]

I'm guessing the intake air temp sensor informs the brain of the intake air
density.  Colder air would be higher density and need a richer mixture for
the right fuel to air ratio.   The sensor stands off the case to some extent
- I think if it was to measure the engine temp it would be fixed closer to
the case.  Does that make sense? 

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 J. Jonik
Sent: 25 February 2011 05:15
To: type3 at vwtype3.org
Subject: [T3] (no subject)

I  said "air regulator"---meant intake air DISTRIBUTOR, of course.    It's
that temp sensor that's disconnected (that made idling etc feel perfect).
   Head temp sensor, is hooked up, of course. Un-do that one and the car
doesn't work.   Undo the other one, and it hums like a top.   Hard to
figure.

Message: 2
Date: Thu, 24 Feb 2011 15:49:53 -0600
From: Jim Adney <jadney at vwtype3.org>
To: type3 at vwtype3.org
Subject: Re: [T3] Old Type IIIs
Message-ID: <4D667E21.5591.4ABD438A at jadney.vwtype3.org>
Content-Type: text/plain; charset=ISO-8859-1

On 24 Feb 2011 at 13:31, J. Jonik wrote:

> Never used an Exhaust Tester. Will visit my friend's shop.? What does 
> an exhaust tester tell you? Is it generally known what a Perfect 
> Balance between rich and lean is?

It should tell you the air/fuel ratio, which should be 14.7:1.

> ? And, couldn't a rich reading mean something besides fuel pressure 
> adjustment is needed?   (My fuel pressure is consistent 29)

There are any number of things that will change the richness. Fuel pressure
is the only one you can actually adjust up and down easily.

> For the record...my 72 FI, with "new" Control Box AND disconnected 
> temp sensor (at Air Regulator) is working just great...driving, 
> accelerating, idling, everything. Mystery is why disconnecting that 
> temp sensor helped the idling oddities so much.? VW must have wanted it
there for some reason.

By disconnecting that sensor, you've set the sensor resistance at infinity.
I think that corresponds to telling the brain that the engine is cold. I
would expect the brain to respond by making the mixture richer.

BTW, a '72 should have 2 temp sensors: one on the left head, just beneath
the
#4 spark plug, and the other in the intake air distributor. Sounds like you
may still have a few things to sort out.



      
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