>
>  Subject:
>         Emission / Air Mass Sensor - could it be the cause?
>    Date:
>         Tue, 5 Sep 2000 17:22:12 -0400
>    From:
>         Wolfgang Ziegler <ziegler@PRINCETON.WIRELINE.SLB.COM>
>
>
>
> Hi,
> I am new to the list - thanks for helping me out. I searched the archives and found some valuable hints.
> Have been facing an increasing problem with my 88 Vanagon (106 kmiles) over several months now:
> Symptoms:
> Very little power, sluggish when below 2000 rpm, especially in warm climate and/or with AC on
> Very high idle emissions (HC close to 1000 - CO 1%), prev. years <100
> No performance problems with O2 sensor disconnected (HC close to 1000)
>
> Steps taken:
> clean and reseat all connections: ECU, sensors, Idle control...
> new sparks, wires, distributor, air filter - timing tuneup
> new temp sensor, O2 sensor
> check for vacuum leaks, check idle control valve
>
> Suspects:
> The resistive layer of the air mass sensor shows wear by the wiper. The 'over-all' impedance is about 300 Ohms (as defined by the
> individual resistors), when measured on the wiper (analog meter) I see the values between 25 (closed) and 300 (open) vary all over the
> place - not monotonously increasing. Is this because of the high impedance of the black conductor or is the unit faulty? What should the
> reading be for the idle position (1/3 open)?
>
> Will a new unit require major adjustment - have not seen anything on a how-to
>
> What is the correct procedure to adjust timing for the Digifant system? - engine warm up - disconnect temp sensor - adjust at 900 rpm?
>
> I appreciate your help - need to get through inspection soon.

Wolfgang,

Your experience sounds very similar to mine. I did not pass Arizona
emissions until
I replaced my AFM. I got one from Bus Depot, dropped it in and breezed
through the tests.

I still have my old one if anyone is interested in it for any reason.

>
> Wolfgang Ziegler

John-Reed Maffeo- '86 Syncro Glacee (for Sale:(
Mesa/Chicago/Dallas