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Subject:Hesitation on 87 Vanagon O2 sensor?
From:Kay O Fremgen
Date:Wed, 5 Aug 1998 01:11:53 -0400

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
kayfremgen@juno.com

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