Date: Tue, 6 Oct 2009 17:15:41 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Stupid Question...... Gasket between AFM and airbox. 1.9 wbx
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I seem to recall a square o-ring between AFM and air box.
and a leak there ( where I think there's on o-ring) won't affect engine
operation. It'll run just fine on the bare
AFM after all. The air box is just for filtering. It'll run fine without
it.
the movement of the sweeper arm is likely the *result* of whatever is
causing the erratic idle.
I'd sure be checking for intake manifold leaks - as those fit the symptom of
erratic idle.
fwiw, air that leaks in, downstream from the throttle plate is called 'air
intake leak' , or intake manifold leak.'
Air that leaks in upstream of the throttle plate, and down stream of the AFM
is called 'false air.;
intake leaks tend to cause roughness.
false air tends to cause lack of response to opening the throttle.
Lots of intake manifold leaks can also cause lack of response to throttle
input.
On one waterboxer engine I found about a dozen air intake leaks in the
intake manifold and plenum.
Even those two screws that hold the fuel pressure regulator on had tiny air
leaks.
The air intake boots.........where the intake runners meat the plenum
..........those love to leak. They're very good at it.
get a listening hose.
hold one end all over the running engine, listening for hisses. The other
end you listen in of course.
an engine is an air pump after all. Air has to go in in the right amounts
at the right time.
The fuel injection depends very much on good tight well controlled air flow
.......in the right places, which mainly means none gets in where it
shouldn't.
here's a fun one :
read your exhaust pipes, right where they connect to the cylinder head with
your infra red temp gun.
Compare the temps. They 'should' all be pretty close to the same.
If you find 3 at say 340 degrees F and one at 250 F ...........that's where
your attention would go - the low one. .........find out why that is
happening, etc.
Scott
www.turbovans.com
----- Original Message -----
From: "T Collins" <tonycollin@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, October 06, 2009 11:00 AM
Subject: Re: Stupid Question...... Gasket between AFM and airbox. 1.9 wbx
> Hello David,
>
> That makes sense. I was trying to see if that was the reason fro erratic
> idle. If I take the pentinometor cover off while the engine is iddling I
> see
> the arm of the pentinometor in the AFM shake and to the tune of the
> erratic
> idle. One can hear the spring under it shake to. I guess that if this is
> leak then it is further down stream.
>
> Then again it maybe that darn TB or its TPS.
>
> Thanks,
> el t.
> --
> 82 Scirocco "Rodolfo"
> 85 Vanagon "El Guapo"
> 90 Fuji Ace
