This idle problem is particularly pesky.  I did solve mine with a new
idle control unit.
However, I've been thinking of other sources of the problem that the ICU
may be masking.
   - checked all vacuum leaks, there were none
   - the oil filler tube is a bit cracked where the plastic meets the
aluminum.  If this black plastic is cracked and air is getting in, could
this affect engine performance?
   - The o-ring where my oil dipstick goes into the engine block is
damaged.  Could this be a problem?
   - My oxygen air sensor on my exhaust is probably old?  If it is not
working properly, could this affect the idle?

As I mentioned, before I dismantled my engine for a rebuild, I had it
running okay with the new idle control stabilizer.  However, I want the
engine to purr after the rebuild, so I'm thinking what I should change.
Also, I am posting here in hopes of helping Tyler with his problem.

Tracy Bonin wrote:

>I had the same problem with my 85' GL until I replaced my idle control unit. Actually I didn't even have one, someone had just plugged the 2 plugs together instead of replacing. When I put it in haven't had any of those problems since. It's like a $10 part from the Bus Depot.
>I'd also check the O2 sensor
>have fun,
>Tracy
>85' GL "Ripple"
> Tyler Bradford <pdx_vanagon@ATTBI.COM> wrote:Hello, all. I'm a newbie here to the mailing list and a new Vanagon owner as
>well. I have a question that I was hoping to get some help with. I have an 85
>Vanagon GL w/a rebuilt engine that is giving me some idle troubles. The problem
>occurs when stopped or when the clutch is in and the engine has had a chance to
>rev all the way down, even if still moving. What will happen is that the RPM
>will go waaaaaaay down, to about 200 or so, and almost stall out, to the point
>where the console lights are flickering. then it will seem to catch and rev
>back up, up to about 800-1400 rpm. As soon as it tops out, though, it will fall
>back down to 200, and the same thing will happen again. This doesn't happen
>every time I am stopped, but probably about 70-80% of the time. Also, sometimes
>the engine will stall completely when turning a corner w/ the clutch in. I have
>tried bypassing the idle regulator (? little black box to left of engine) to no
>avail. I have also replaced the air filter recently. Any input would be greatly
>appreciated. Thanks.
>
>

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Craig Oda's Personal Email
Living and Working in the SF Bay Area
Automobiles: '83 VW Westy (watercooled); '77 VW Bay Window
Other Info: http://communitybuilders.info/~craigoda/