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Old 05-03-2003, 04:52 PM
ke6dcj ke6dcj is offline
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Join Date: Apr 1999
Posts: 2,638
BTW: here's the OBDII drive cycle aka, test cycle:
RUNNING AN OBDII DRIVE CYCLE

Suppose youíve "fixed" an emissions problem on an OBDII-equipped vehicle. How can you check your work? By performing whatís called an "OBDII drive cycle."

The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle shold be performed after youíve erased any trouble codes from the PCMís memory, or after the battery has been disconnected. Running through the drive cycle sets all the system status "flags" so that subsequent faults can be detected.

The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).

NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.



1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.

2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.

3. Hold at a steady state speed of 55 mph for three minutes.


OBDII monitors EGR, air pump, O2 sensors and canister purge.



4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.

5. Accelerate back to 55 to 60 mph at æ throttle. OBDII checks misfire, fuel trim and purge again.

6. Hold at a steady speed of 55 to 60 mph for five minutes.


OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.



7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
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