Date:         Mon, 5 Feb 2007 08:03:17 -0500
Reply-To:     William Greenamyer <greenamyer@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         William Greenamyer <greenamyer@YAHOO.COM>
Subject:      Re: CSI: Vanagon...Smog results!

Below you say to set the idle RPM to 950-1000.  That happens to be where my
van (84GL) passes.  It does not pass at Bentley value of 650RPM.  What is
happening at  950-1000 that is not happening at 650RPM?  Is it just the heat
of the CAT or is there something else we should be considering?

William

On Wed, 31 Jan 2007 23:41:34 -0500, Dennis Haynes <dhaynes@OPTONLINE.NET> wrote:

>The crossover pipe on top of a giveaway. 1.9. The single pulley indicates it
>most likely was a late '83 with the extremely early cooling system and it
>may even have that odd ball 190 mm clutch and flywheel.
>
>Now for your emissions failure results.
>
>Your test is basically an idle speed and 2,500 rpm test. You failure was
>both HC and O2. From a diagnostics point of view this is extremely valuable.
>You r test results provide the justification for these testing programs. You
>are a gross polluter putting out fumes like a Model T or a bad lawnmower.
>
>As a recap for the group, the test limits are 1.2% CO and 220 ppm HC. These
>are typical limits and all cat equipped vehicles should reach it, even
>without a working cat. For information, the Dyno tests (IM 240) is  used to
>put the drive train under a sustained load to test for NOx production. This
>tests the 3-way part of the cat, (CO, HC, NOx) and for engines so equipped,
>the EGR function. Changes in ignition timing, gearing, compression ratios,
>etc have adverse effects on NOx.
>
>Anyway, your results were 9.99% CO, 1700 ppm HC at idle and 8.63% CO and 255
>ppm HC at 2,500 rpm. The O2% was .2 at 2,500 and 5.6 at idle.
>
>Normal atmosphere O2 is at least 19.5% these readings tell me the thing is
>running real rich. There is obviously no O2 sensor control. The fact that
>the HC drops at 2,500 rpm tells me there may also be an ignition, timing or
>valve problem.
>
>First thing to do is test the O2 sensor. Put meter on it. Measure between
>the sensor lead and a good chassis ground. With things cold, when you first
>turn on the ignition, you should see ~.6 volts. The is the leakage or bias
>voltage on the ECU amplifier input. A cold sensor is an open circuit so you
>will see that. Now start the engine. As the sensor warms, you may see the
>voltage drop but it should soon increase. Since you are so rich, you should
>see close to 1.0 volt or maybe more. If not, sensor is shot.
>
>Next, after we know we have a good sensor, remove the cover from the AFM.
>Disconnect the sensor from the ECU and connect it to the meter. Start engine
>and watch voltage on sensor after it warms up. While engine is running,
>gently turn AFM wiper opposite the direction the airflow is pushing it. The
>engine should lean out and the sensor voltage should drop. Using the plastic
>wheel, tighten return spring to get the sensor reading to around .5 volt.
>Rev the engine and see if you can get it close to that voltage across the
>range. The idle bypass screw can help get the idle speed tuned if needed. I
>usually just set it 2 turns open and a properly functioning system will take
>it from there. Re-connect the sensor to the ECU. You should be able to see
>the sensor reading vary from .2 to.8 volts. You now have O2 sensor control.
>If the throttle switch is working right, you can rev the engine to say 1,800
>rpm, let go of the throttle, and see the O2 reading go to "0" for a moment
>as the engine slows down. This is due to the fuel shut off when the engine
>is above 1,300 rpm and the throttle is closed. Now, when the fuel is
>resumed, the O2 sensor is ignored for 30 crank revolutions. This is why the
>base mixture setting is critical. If the mixture is too rich without the O2
>control, the engine will creep above the cut off speed, fuel is shut off,
>the speed drops, and the cycle will continue. This is that famed Digi-jet
>idle surge.
>
>For the basic settings, make sure the distributor vacuum advance and retard
>are both working. Set the timing at the correct setting, over advanced will
>increase HC at idle. Set warm idle high at 950-1,000 rpm. Makes a big
>difference. Make sure the auxiliary air regulator is working, getting 12
>volts and closing quickly. If the basics are set correctly, you should no
>problem passing those limits.
>
>Dennis
....