Can the QCSC DAS SYSTEM help solve emissions complaints? YES

Why is CO high at idle? Why does the CO increase to 9% off idle and the HC's go off the scale? Can it be the VAF spring has lost tension with the passing of time?

EXPLANATION OF WAVEFORM: Each gridmark represents 5 seconds. Every time we open the throttle, the VAF signal voltage drops. This is normal for some VAFs. Read the notes in the image for more info.

In case your wondering, this car had a history of just barely passing the loose standards idle test, and fuel mileage was poor. The problem had become worse with the passing of time. The car had not set a DTC because the problem was a shifted sensor signal, not a failed sensor signal. Disconnecting the VAF caused the o2 sensor voltage to drop, the pulse-width to shorten, the idle to smooth, an off-idle stumble to disappear, and the computer to set VAF and air temp codes.

For more Nissan tips, contact Bob.

Waveforms Courtesy of:
BOB POWELL'S AUTO REPAIR, East Longmeadow, MA -- 413-525-0855 -- sw686@the-spa.com

See normal ref, sync, injector, and spark plug waves.

For more info, call: Quad Computer Systems Consultants, 973-472-0328, ASK FOR DAN

EMAIL to; qcscdas@aol.com or EMAIL to; lody@delphi.com
Please entitle email inquiries -- QCSC DAS
VISIT; QCSC at Delphi or VISIT; QCSC at AOL

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QCSC DAS Copyright 1998 -- Developed by; Daniel A. Buckley (NIASE GAM)

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