Date: Wed, 2 Oct 2002 12:03:54 -0400
Reply-To: "Warner, Jeff (DSIO-MS)" <Jeff.Warner@DSIO.DLA.MIL>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Warner, Jeff (DSIO-MS)" <Jeff.Warner@DSIO.DLA.MIL>
Subject: O2 Sensor Installed and CO adjustment problems (Sorry, Long)
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Ken and Vonderful List Volks
I temporarily installed your O2 sensor last night in the engine bay. Very
nice little device. I had to go back to your website (
http://neksiwel.20m.com/photo5.html ) this morning to discover that I was in
fact looking at the gauge upside down. I couldn't understand why it would
indicate full lean (left) when I'd rev up the motor. Now I understand that
it was indicating full rich so it's making more sense now. I had my
suspicions. Tonight, I'll flip it over (solder side up). Anxious to get it
in the dash.
I've been working on running through the entire Bentley tune-up process with
the suspicion that I've got a lean out problem under load. ('86 2.1 Auto w/
A/C) Anyway, last night, I started at the beginning by checking the throttle
stop adjustment, adjusted the throttle position switch, checked and replaced
vacuum lines, checked and replaced engine grounds, confirmed the timing was
5 BTDC, checked the timing advance function, set the idle and then started
working on the idle/CO adjustment. Here I ran into some problems.
Don't know if you can remember or help with any of this but thought I'd ask
anyway. I'm asking the list too. There are some discrepancies between the
Bentley and the VW Technicians Guide for Solving Drivability Problems. The
discrepancies revolve around the removal and plugging up of the crankcase
ventilation hose. This problem also exists for the procedures for setting
timing. For instance, when setting timing, the guide (which for the most
part mirrors the Bentley), instructs you to remove the hose connected to the
"crankcase ventilation valve and plug it" (not sure that's an exact quote)
whereas the Bentley has no such instruction. For setting the CO and idle,
this instruction is present in both books but it is still unclear to me.
Here's my main confusion: What is the crankcase ventilation valve and what
am I supposed to plug, the valve or the hose? Are the instructions
referring to the crankcase vent tower (don't know proper description) next
to the pulleys that the crankcase pressure comes out of or is it that little
valve like device that is mounted between the intake boot and the crankcase
hose? What is that thing anyway? I can't find it documented in the Bentley
except in pictures. Seems it ought to be some kind of PCV valve but what
are the electrical leads going to it doing? So, anyway, do I disconnect the
hose from the tower and clamp the hose, letting the crankcase vent freely or
do I disconnect the hose from the little PCV valve like thingy and clamp off
the hose causing a buildup of crankcase pressure within the engine (which I
wouldn't think would be a good thing and the PCV valve thingy would be open
to outside air) or do I do something else like plugging the PCV thingy and
leaving the hose off? Oh the confusion!
If I remember right, I went with the Bentley for setting the timing and just
left the hose alone. End result was I got 5 BTDC exactly as I had set it
before. So that was good.
As for the Idle/CO adjustments, I don't recall what I did with the hose
anymore. It was late and as I mentioned before I was confused with what I
was seeing on your gauge. I tried hooking up my voltmeter parallel to your
gauge but I got the impression it was affecting it somehow so I left it
disconnected. I eventually got the CO adjustment to the point where it
would tend to dance from side to side but most of the time it would read
full rich or full lean. I could never get it to stay near the middle.
After reading your web page again this morning, , I now understand that
fluctuating back and forth would be normal but I'm seeing very slow
fluctuation in that it goes lean, stays there for several seconds and then
goes rich, stays for several seconds and then back to lean and repeats.
According to your web page this would indicate a lazy OXS. It seems though
that it's just the engine and the ECU reacting too slowly to the input from
the OXS. The OXS detects a change in mixture, the ECU picks it up, changes
the enrichment, you hear the idle change and then the OXS detects the new
change and we go the other way. This process seems to be happening maybe
too slowly and of course is causing a bit of a hunting idle (900-1000 RPM).
Maybe the OXS is just too slow in detecting the changes? And around and
around I go!
Anyway, I was just looking for some additional input to all this, especially
the crankcase hose thing. I did proceed on to testing the CO adjustment
function by removing the regulator vacuum line and that seems to work fine
now that I know which way is rich on the gauge. Of course, I haven't even
started approaching my lean out problem. Still have to check fuel pressure
at the regulator and possibly flow rate at the pump. And then there are all
those wonderfull AFM tweeks to consider.
For those who've made it this far, I also got under the van and checked out
the fuel filters since this is an '86 Westy. I've got both filters and the
plastic one has never been changed. It has the large diameter connections
at both ends (same as the tank fitting). Also, the pump is original.
YIKES! Only 98,000 miles but I think it's time to find a spare. I already
had a Vanagon pump leave me stranded on the Ohio Turnpike at two in the
morning once before. Would rather not repeat that again.
Any input to the proper procedures regarding the crankcase ventilation hose
and CO adjustment and/or proper OXS behavior would be greatly appreciated.
Oh, and yes I've been to the archives many times and know them well.
Jeff Warner
Galloway, OH
VW stuff scattered all over the shop!
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