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Date:         Mon, 10 Aug 1998 08:14:49 -0500
Reply-To:     Darrell Boehler <midwesty@TAOS.MIDWEST.NET>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Darrell Boehler <midwesty@TAOS.MIDWEST.NET>
Subject:      Re: 87 Vanagon hesitation continues
Comments: To: Kay O Fremgen <kayfremgen@JUNO.COM>, Vanagon@VANAGON.COM
Content-Type: text/plain; charset="iso-8859-1"

----------------------- Hi Kai, The coax wire has been found shorted to ground by several on the list lately. It goes from digifant ECU pin 2 to the oxygen sensor connector, from this connector to the black wire on the oxygen sensor. My coax wire / ECU pin 2 measures about 0.5 volts with the oxygen sensor disconnected. This wire measures 182k ohms resistance to ground with a vw ECU and 220k with a bosch ecu plugged to digifant cable.With the ecu disconnected it measures infinite. One of these checks should net you a pretty good clue to your problem. Best of luck to you and your van.

Darrell

Ps. Another test of the ECU and oxygen sensor wire is to start the van with the oxygen sensor disconnected and let it idle for a couple of minutes. Then touch the wire going to the ECU to ground, the engine will start running rich . If you touch it to a 1.5 volt battery plus that has the minus side on ground the van should start running lean. Something here should not leave you clueless.

-----Original Message----- From: Kay O Fremgen <kayfremgen@JUNO.COM> To: Vanagon@VANAGON.COM <Vanagon@VANAGON.COM> Date: Monday, August 10, 1998 12:50 AM Subject: 87 Vanagon hesitation continues

>Hi again, >Original message below >I have changed the O2 sensor and the problem persists. >With sensor disconnected the van accelerates smoothly, with the sensor >connected the van hesitates. With O2 sensor hooked up the volt meter is >showing 0 to "negative" 0.05 volts for about 3 to 4 seconds during >acceleration. Another observation: during deceleration above 1250 rpm >fuel is being cut off to the injectors (with O2 sensor disconnected from >computer and the volt meter hooked up to the O2 sensor) the volt meter >reads "negative" 0.05 volts if I engage the A/C compressor the voltage >then goes to "negative" 0.1 volts. Could this be due to bad ground? > >Help me please! > >Kai >87.2 Westy > >Hello All, >Went through the Digifant/Bosch system and came up with a O2 sensor >question. With O2 sensor unhooked from the computer the engine will >accelerate fine under load (AC compressor on).With the sensor hooked up >the engine has severe hesitation. One would think: exchange the O2 >sensor and get on with your life, but here's the kicker. With the volt >meter hooked up to the now back inline O2 sensor I'm getting readings >which to my knowledge are correct. In idle the volt meter bounces back >and forth between 0 and 0.6 volt. During acceleration under load (A/C >compressor on) the volt meter then drops to "negative" 0.1 volts for >about 3 to 4 seconds which is approximately the same duration of the >hesitation. Indicating a lean mixture. > >Question #1: Isn't this exactly what the O2 sensor is supposed to do? >Question #2: Why is the computer not compensating for this voltage drop? >Question #3: Why am I getting "negative" 0.1 volts for about 3 to 4 >seconds? (using analog gauge need to switch polarity to measure negative >volts) >Question #4: Will a new O2 sensor fix this problem? > >Additional data if needed, compression check #1: 150, #2: 175,#3: 135, >#4: 165. Vacuum test (intake manifold) at idle 14.5 in. at 1500 rpm 17.5 >in., at 2000 and up 20in. Hg (Live in Florida elevation 0) 135000 Miles > >Any help is highly appreciated, Thank You > >Kai 87.2 Westy > >_____________________________________________________________________ >You don't need to buy Internet access to use free Internet e-mail. >Get completely free e-mail from Juno at http://www.juno.com >Or call Juno at (800) 654-JUNO [654-5866] >


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