[T3] '72 FI won't idle down

[Keith Park]

I shoved a restrictor bushing in the hose then clamped the hose around it so
it had no chance of working loose.  3mm was what Ray found would work
When properly tuned, I did noodle with size and found that 3mm was right for
my application.  Remember, this is T4, still Djet but things maybe routed
differently

MY biggest problem is that the T4 uses the electric AAR, which doesn’t have
the pot metal problems but doesn’t stay warm as well as the one stuffed
right into the crank case oil so it
Tends to open too quickly when the engine has been shut off and then the
idle is too high till it closes AND the engine runs too lean till it closes
so you feel it miss under acceleration for a couple miles. I used
 a DCtoDC converter to boost the 12V up to 15.5 and that gets it to reclose
faster, but still not enough... next thing Ill try is a thermostatically
controlled solenoid that ONLY allows air thru the AAR when the block
is cold enough.  That should correct the issue.  With the tuning for the
2056 getting the warmup curve to track properly with an open loop stock
system is a bit challenging.

Keith


Topnotch Restorations
topnotch at nycap.rr.com
http://www.topnotchresto.com
71 Squareback  “Hothe”
65 Notchback  “El Baja Rojo”
93 RX7  “Redstur”
13 Subaru Outback "Blendin"

-----Original Message-----
From: type3-vwtype3.org <type3-vwtype3.org-bounces at lists.vwtype3.org> On
Behalf Of David
Sent: Thursday, June 11, 2026 12:55 PM
To: type3 at vwtype3.org
Subject: [T3] '72 FI won't idle down

After further review - I reread Keiths response and realized I
misinterpreted what he wrote.

[[[One thing I had to

do was put a restriction in the line to the crankcase breather, something
Ray Greenwood suggested, about 3mm, that seemed to work and allowed it to
breath but kept idle within range.]]]

I believe I now understand that the added restriction is between the PCV
valve and the IAD, which would in fact reduce the amount of air that passes
between these 2 components - while still allowing enough air for the PCV
system to function normally. Less air into the IAD = lower idle speed.

The part I still don't understand is the 3mm part. What & how creates the
3mm reduction?

Dave Pallo

'72 Square ~ Elwood

Fairport, New York

 

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