[T3] Old Type IIIs (Exhaust Tester)

Daniel K. Du Vall dduvall at 1peter4-10.org
Fri Mar 4 17:01:04 PST 2011


Too rich or too Lean can also cause High hydrocarbons unburnt fuel is a hydrocarbon. Thus the vapor collection systems you sometimes see at the gas pumps here and the systems on newer and some older cars. 

Daniel Du Vall
http://1peter4-10.org
http://volkswageninsanity.us


-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Dave Hall
Sent: Friday, March 04, 2011 4:36 PM
To: type3 at vwtype3.org
Subject: Re: [T3] Old Type IIIs (Exhaust Tester)

If they can tell you the unburnt Hydrocarbons are high (1200ppm was the
limit in the UK), suspect valves or worn bores.

If the Carbon monoxide is high (over 1% for injection or 3% for carbs) the
mixture is too rich.  Don't aim for 1% for FI - I think it should be less
than that.

If they can't tell you these levels, maybe they can 'translate'.

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: 04 March 2011 20:21
To: type3 at vwtype3.org
Subject: [T3] Old Type IIIs (Exhaust Tester)

Back in Feb. I got the advice below about testing Air -Fuel balance with an
Exhaust Tester.  Mix should be  14.7  : 1 ...meaning 14.7 parts air to 1
part fuel, I assume.

But, it seems that garages don't automatically have Exhaust Testers
nowadays...they use computer equipment that doesn't test for fuel-air
ratio.  

So, If I find a garage that has Exhaust Tester, and if there's a little too
much fuel, can this be easily corrected by lowering the Fuel Pressure
adjustment?  My fuel pressure is a constant 29.  Should I adjust to
28...which is what's needed anyway?  Can that one fuel pressure point make a
noticeable difference?

 Car's still running (and idling and starting and accelerating) alarmingly
perfectly.   I'm not used to that.

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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