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Re: [T3] AAR Resolved, and some questions about idle.


Jim Adney wrote:

>This kind of valve never seals perfectly, but it DOES cut down the airflow to 
>next to nothing. Feeling for suction is the wrong test. The right test is to 
>see if the idle changes noticably, once warmed up, when you close off the 
>opening with your thumb.
>  
>
Ok, so the thumb over the hose test drops it to 5-600 RPM.  I can get
the idle down to around 900 by plugging most of the AAR hose but leaving
a tiny orifice open with my thumb- but I know the AAR is closing up by a
visual inspection. What does this mean?

>A wild hunting idle is normal if the idle is set too high. Put it down to 900-
>950. Make sure you have hoses on all the nipples, or you won't be able to get 
>the idle down properly. It's also possible that there's a vacuum leak 
>somewhere, but I recommend that you NOT do the typical fix of adding hose 
>clamps to all the fittings.  
>
>  
>
The only vacuum hose I didn't change was the vacuum modulator hose. I
changed the pressure sensor, vacuum advance, and all breather hoses
(including the one from the crankcase breather to the back of the IAD).
The VM hose appears original (the hose itself seems almost ribbed
lengthwise in texture), and a best-effort visual inspection revealed
nothing obvious. That said, it could be leaking. What size hose is this?
5/16?

I also noticed that the port for my vacuum advance on the IAD was
clogged- I unsealed this with some throttle body cleaner and a thin
wire. Sucking on this hose makes it seem like the port is a pinhole.
That's correct, right? Perhaps this was the culprit for the dipdown on
acceleration?

>The 4 short large hoses at the sides of the IAD are often suspected of leaking 
>and I see a lot of hose clamps on those when they're not needed. Instead, take 
>care not to tighten down the IAD before the intake runners are tightened. Then 
>you may want to rotate the large hoses so that they are in their most 
>unstressed orientation.
>
>  
>
I have a crusty old IAD I got for parts and it still had the intake
runner hoses on. Even in thr crustiest conditions, it appeared to seal
well enough. They were actually still pliable and reasonably tight. I
feel comfortable with the IAD connectors being OK.

>44 should work fine, but 50 is better at high rpm.
>
>  
>
That's what I'm going to adjust for. I got 44 by doing the feeler gauge
for .016. Makes sense I'd hit the lower edge of the dwell range.

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