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2001 Pontiac Grand Am Question: How do i complete drive cycle

 

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Midyett3, 3.4L V6, Gerald, MO, November 24, 2013, 09:03
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Cat not complete or evap

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  • Answer #1

    G. T. Service Center (4215 Answers) , Stephenville, TX - (254) 638-3236
    ProfessorG November 24, 2013, 09:37
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    When engine is cold, or has sat long enough to cool down. Start the engine, let the engine warm to normal operating temp, usually by driving the vehicle, then park the car and shut the engine off. Considered 1 drive cycle. What are you wanting to know, EVAP operation?

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    Midyett3, November 24, 2013, 19:02
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    do I have to do drive cycles or will it do it if I just drive it normaly for a couple day I was told I may have to drive it a couple hundred miles to get them to run it is 16 degrees here

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  • Answer #2

    cardocIII from Gillespie's Auto Service, November 24, 2013, 11:02
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    To get a full OBDII drive cycle on your car you need to start like prof said by letting the car sit until the engine has cooled to close to ambient temperature. (That temperature also has to be between 39f and 85f). Do not start to try and do a drive cycle with the check engine light on, some codes can block certain tests. You may have to clear codes, but if you have some set, post them before you just clear them.

    Start the vehicle and drive it for about four miles at speeds between 30 and 45 mph with at least two stops. Now increase the speed to 55-70 mph for at least five minutes.

    Next back to a rural highway speed between 40-50mph. You have to accelerate to 50mph and then decel without stepping on the brake for twenty seconds, repeat two more times. After the third time, pull off the road and stop letting the car idle in gear for thirty seconds. Then put the car into park and idle for 120 seconds.

    Now drive it on the local roads for approximately 3 more miles at various speeds and with some city driving (short normal accelerations, with stops of a few seconds). Check for pending codes (global mode 7) and readiness monitor completion.

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    Midyett3, November 24, 2013, 19:04
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    does the fact that its 16 degrees out side effect the evap test and cat test I have driven it for about 255 miles it still hasent done the cat and evap

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    cardocIII, November 24, 2013, 19:34
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    "does the fact that its 16 degrees out side effect the evap test and cat test I have driven it for about 255 miles it still hasent done the cat and evap"

    Yes. The evaporative monitor won't run when it is that cold out. That's one of the challenges in dealing with OBDII diagnostics. We stress understanding the code enable criteria and when there are blocking conditions, or if something can cause a monitor to be suspended. The catalyst monitor however still has a chance to run on a GM even if it is that cold. (A Ford easily might not run) If you do the drive cycle as I outlined, the catalyst monitor runs at idle after the three speed up and 20 second decelerations. There is a minimum air temperature, but it should be warm enough at idle under-hood to still reach it. Situations like this are why we have to evaluate if clearing the codes is the best choice, sometimes its better to not clear them.

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