> > 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 |
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