[T3] high idle: FIXED

Jim Adney jadney at vwtype3.org
Sat Jun 9 13:08:49 PDT 2012


On 9 Jun 2012 at 11:44, Chris Slaymaker wrote:

> Today, I put zip ties on all the boots connecting the IAD with the
> intake runners.  FIXED.  I bought these from one of our online vendors
> and they were Gates brand. 

The root cause of this is poorly positioned parts when an engine is 
rebuilt. The AID must be left loosely installed until the air runners 
are all in place, then the air runners and the AID tightened 
together, into non-stressed positions.

Often, if you're rebuilding an engine that has already been rebuilt, 
you'll find that the boots have been stretched into a sideways 
offset, because they were done wrong previously. When I'm taking an 
engine apart, I try to slide those sleeves back onto the air runners 
to try to get them to straighten out while I'm rebuilding the rest of 
the engine, but it often take some effort to get everything lined up 
and sealed nicely, expecially if everything's been misaligned 
previously.

It's also possible for the individual air pipes to get bent. 
Sometimes I have to bolt everything into place as best possible, with 
the sleeves slid back completely onto the pipes. Then I bend the 
pipes just enough to get all the ports to line up perfectly. Only 
then do I try to slide the sleeves into positon.

Yes, you can get around this with cable ties or hose clamps, but it's 
better to do without those, because that allows things to slide as 
various parts heat up and expand differentially. Done right, extra 
parts are not needed. I have a rather large collection of hose clamps 
that I've taken OFF engines I've worked on, but usually takes a bit 
of effort to make them unnecessary.

If your sleeves are in really bad condition and you want a fresh 
start, I have good sleeves, both new and used.

> I had first checked the manifold pressure sensor, but since it is more
> or less a black box that is still unmolested, I didn't venture into
> it.  I dumped a lot of oil out of it however. 

I used to clean mine out regularly, too, but I stopped after it 
became clear that it never seemed to make any difference. The last 
couple years the MAP port on the IAD goes into the TOP of the IAD. 
That's a great improvement in my opinion, as this keeps pooled oil in 
the bottom of the IAD from running right down into the MAP hose. It's 
also easy to see and install, unlike the first 4 years.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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