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Date:         Fri, 11 Aug 2006 09:08:56 -0700
Reply-To:     Michael Diehr <md03@XOCHI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael Diehr <md03@XOCHI.COM>
Subject:      Re: 1000 mile rebuild recommendations?
Comments: To: Kenneth Lewis <kdlewis@NORTHSTATE.NET>
In-Reply-To:  <008601c6bcd1$baa57470$0201a8c0@kaos>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

I think one or both of the previous mechanics have already messed with the AFM -- the black plastic cap can be removed with gentle pressure, and the adjuster screw plug has already been drilled out. Maybe it's just a crudy rebuild and can't be adjusted back into spec?

Also, I notice that at idle, the spring bounces all over the place, but the idle seems to smooth out a bit if I hold it steady. Is that normal for it to vibrate like that?

Thinking maybe I should just buy another AFM and do the debug-by- parts-swap method...?

On Aug 10, 2006, at 4:07 PM, Kenneth Lewis wrote:

> Michael, > Just because the AFM is rebuilt doesn't mean it's good. Possibly the > spring is not tensioned correctly. I wish there was a good > procedure out > there to tune them. Here are some things I have learned by > experimentation. > YMMV. > > First you need a good voltmeter and O2 sensor. The three throttle > body > alignments outlined in the Bentley should be checked. Carefully pry > the > black cap off . If you don't mess it up too bad it will go back on > and stay > without glue. Drill out the plug so the allen screw is accessible. > Use an > allen wrench and determine the base setting of the allen screw. > That is, > find out how many turns until it bottoms out so you can return to > where you > started, just in case. Write it down. Likewise mark the black > plastic wheel > so you can return it to it's original starting place. > The engine has to be up to operating temperature. Disconnect the O2 > sensor and hook up the voltmeter to it. If it is running lean the > reading > should be near zero. Ideally the voltage should toggle equally > between zero > and (about) one volt. > Off the top of my head I can not remember which way to turn the > wheel to > enrich the mixture. I noticed that after a few notches in the right > direction the engine RPMs picked up and smoothed out. Unfortunately > the > spring tension that equated to the best sounding idle did not give > the best > reading from the O2 sensor. This is the part where I wish I had a good > procedure written out. I fiddled with the spring tension and idle > screw (on > the throttle body) until I got a happy balance between idle and > good O2 > sensor output. Use the allen screw to fine tune the O2 output voltage. > Hopefully the output is good at higher RPMs, otherwise you need to > adjust > for that. > I run through this procedure every year before vehicle emissions > testing. > Good Luck, > Ken Lewis > http://neksiwel.20m.com/ (more O2 info here)


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