1FastBrick

iTrader: (17)

The Evap has to be done with tank range between like 15-80% from what I recall. But it also has to be above 65 degrees ambient temp out side. You can force the test with a Bi-directional scan tool like the Tech2.

Usually the O2 monitors set when the Catalyst Monitor sets.

To perform an OBDII Driving cycle do the following:

1. Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
2. Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge “No Flow”, Misfire and if closed loop is achieved, Fuel Trim.
3. Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
4. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
5. Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
7. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
8. Decelerate. This will perform the same diagnostics as in step 5. Again, don’t press the clutch or brakes or shift gears.

marktm250

I've done that GM "drive cycle" several times - in addition to putting several thousand miles in recent trips - with no "readies" of the evap and O2 sensor. I did disconnect the battery recently, so I'd guess I'm starting over. Beginning to wonder about going to my dealer and ask them to get a "waiver" based on all sensors appear to be working well and no DTCs.

1FastBrick

iTrader: (17)

They also recommend the tank being around 1/2 full. I believe the systems only performs the Evap test between 15%-85% range. It's the hardest one to set

I believe along with the drive cycle specifications mentioned above you have to drive at least 10 miles. I recall the Scan tool has a timer as well as a specified range you have to drive to complete the cycle. Then they have you cycle the key.

marktm250

Not familiar with any requirement of cycling the key. I just drove another 100 miles or so with at least two "drive cycles" included - evap and O2 sensors still not ready. Not DTCs and all others "complete". Going to check with the dealer tomorrow. I do have over 140,000 miles on the 4 O2 sensors.