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Thread: Smog Check

  1. #1

    Smog Check

    I just got my CA smog test done, and although she passed, it was too close for comfort.

    Hydrocarbons at 15mph: 49 vs average of 4 and max allowed of 50.
    Hydrocarbons at 25mph: 33 vs average of 4 and max allowed of 34.

    Seems really high to me, but I don't have access to my files to see what the numbers were two years ago from the same shop. Does anyone else have some comparable numbers? '01 car with 11k miles; test done in Santa Monica at the Pico/Cloverfield station.

    Thanks in advance,

    Tyler

  2. #2
    This is cerainly a worry, but I have no information on these figures from anyone as yet - I would suggest that from now on we all post the emission test results here to get a better idea of the output of our engines.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  3. #3
    Z8 Ate My Homework! Norcal's Avatar
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    Mine is coming up this month, I'll post it.

  4. #4
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    Test done at Irvine BMW, 2/7/07 with 17,000 miles
    15 mph, %CO2-15.3, HC-15, CO-.02, NO-13
    25 mph, %CO2-15.4, HC-8, CO-.03, NO-16
    All are about average but the Hydrocarbons are higher than the 4 average.
    good luck

    Steve

  5. #5
    Administrator thegunguy's Avatar
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    Quote Originally Posted by Norcal View Post
    Mine is coming up this month, I'll post it.
    This raises a interesting offline question....
    thegunguy

  6. #6
    Z8 Ate My Homework! Norcal's Avatar
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    Quote Originally Posted by thegunguy View Post
    This raises a interesting offline question....
    I should be gettinng mine checked by the end of the month I hope.

  7. #7
    Administrator thegunguy's Avatar
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    That's great to hear!
    thegunguy

  8. #8
    Thanks. Any thoughts on what could be the problem? Clearly its not burning fuel efficiently. Quick guesses would be MAF or O2 sensors, but the check engine light is not on.

    Tyler

  9. #9
    I just tested one in our shop and the results are:
    HC
    15mph - 13
    25mph - 9

    Was the car fully warm? If it was not that could be the problem. I would have it checked to see if any faults are logged. There are many things it could be and to guess from afar would not be a good thing to do. I would check for faults though and depending on the outcome, start looking for air leaks on the intake side (gaskets, etc) It could be an oxygen sensor acting up as well although that should illuminate the check engine light.

    Good luck,
    Dana Caldwell
    Service & Parts Director
    Peter Pan BMW

  10. #10
    Sport Button On - DSC Off FWK-Z8's Avatar
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    Thankfully, I don't live where they have to do the dyno test. I just had myZ8 checked at idle and 2500 RPM. It tested amazingly clean

    .....................CO2 ................HC(ppm).................... CO(%)............
    ..................................MAX... AVE... MEAS .....MAX...... AVE.... MEAS
    IDLE ..........14.70%...... 100... 17 .........7........ 1.00...... 0.00..... 0.03
    2500 RPM ...14.50%...... 130... 12......... 7........ 1.00...... 0.10..... 0.02

  11. #11
    Z8 Madness
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    2002 @ 16631 miles
    Test performed at Sterling BMW, CA

    15mph %CO2=15.8 %O2=0.0 HC=50 %CO=.02 NO=1
    25mph %CO2=15.7 %O2=0.0 HC=34 %CO=.03 NO=1

    Looks like the HC is at the upper bound. This worries me a bit. I wonder if this has anything to do with the carbon buildup issue.
    2016 Porsche GTS/MT

  12. #12
    Sport Button On - DSC Off FWK-Z8's Avatar
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    Thankfully, I don't live where they have to do the dyno test. I just had my Z8 checked at idle and 2500 RPM. It tested amazingly clean

    .....................CO2 ................HC(ppm).................... CO(%)............
    ..................................MAX... AVE... MEAS .....MAX...... AVE.... MEAS
    IDLE ..........14.70%...... 100... 17 .........7........ 1.00...... 0.00..... 0.03
    2500 RPM ...14.50%...... 130... 12......... 7........ 1.00...... 0.10..... 0.02

    These are my numbers from earlier this year. I live in the Central Valley and thus have the less stringent tests.

    I have heard others have problems with other BMWs. Unburned HC's is a strong function of engine and catalyst temperature. There are procedures in the test to make sure it is done on a warmed engine, and I know others who have had their cars fail because these weren't properly followed. I'd recommend taking your car for a nice 50 mile run before the test. Stay with the car and make sure it doesn't sit around all day before testing it.

  13. #13
    Z8 Madness
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    I spent some time on the M5 Forum and it seems like the HC is all over the place -- even for the same car tested back to back.

    So I tend to agree with you that engine/cat temperature probably plays a big part. On the day of my test, the car sat at the service department for about 1 hour before it was taken in. The temperature on that day was in the upper 60s, so it makes sense that the engine may have cooled down substantially during the wait.
    2016 Porsche GTS/MT

  14. #14
    Administrator thegunguy's Avatar
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    I find humor in the paradox of the California Car Culture vs. California Emission Tolerance.
    thegunguy

  15. #15
    Sport Button On - DSC Off FWK-Z8's Avatar
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    Must be some land in Nevada for $50 you could put an old house trailer on to get some NV plates

  16. #16
    Z8 Addict Z8doc's Avatar
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    Andrew, would a previously undiagnosed or early...

    Quote Originally Posted by macfly View Post
    This is cerainly a worry, but I have no information on these figures from anyone as yet - I would suggest that from now on we all post the emission test results here to get a better idea of the output of our engines.
    Vanos problem noted on the earlier models of the Z8 be the problem?
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  17. #17
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    The semi annual smog inspection hit once more and in lieu of the dealer performing the test, I took it into the local smog station where it failed on hydro carbon at 25 mph, 34 ppm allowed, 37 ppm measured. A retest was free, so with a bit of hard driving, the fun part, to get the cats up to temperature, the ability to drive right onto the test ramp, and the tester runing the rpm up to 2500 for a minute prior to the test to warm the cats, we were able to bring the HC measured down to 26. Passed. Still a substantial increase over 2 years ago. (See previous post). Dana Cadwell's post on getting the cat temperature up worked it's charm. Why? To quote a local BMW guru mechanic, Joe Schneider; "Just keep driving it until it gets worse, then we'll be able to determine the problem." That issue related to some drivetrain noise on my 2800CS, and he was hard of hearing.

  18. #18

    Two years later...

    Back after two years for my next test. Car has about 14k miles now. This time, I instructed them to make sure the car is fully warmed up before the test.

    Hydrocarbons at 15mph: 41 vs average of 4 and max allowed of 50.
    Hydrocarbons at 25mph: 27 vs average of 4 and max allowed of 34.

    Lower than before, but still seems high to me. I should note that this time I have fault codes for both Exhaust Cam Position Sensors, so I'll replace those next week along with the two Intake CPS' for good measure.

    Tyler

  19. #19
    Also maybe consider changing the MAF's as they tend to go off over time too, and can cause the car to run poorly.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  20. #20
    Z8 Madness
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    My 2003 @ 197 miles went in for smog:

    15mph %CO2=15.2 %O2=0.2 HC=0 %CO=.01 NO=0
    25mph %CO2=15.1 %O2=0.0 HC=1 %CO=.04 NO=0

    I don't know what to make of it, but the HC on these cars measures near the max, but in my case, it measured 0. Milage related? Chaos theory?
    2016 Porsche GTS/MT

  21. #21
    2001 with 15,800 miles. HCs at max again. Perhaps not warmed up enough, but most likely chaos theory as suggested above. Car drives great with no codes.

    15mph %CO2=15.3 %O2=0.0 HC=50 %CO=.02 NO=3
    25mph %CO2=15.3 %O2=0.0 HC=34 %CO=.03 NO=4

  22. #22
    DSC Off CraZ8's Johnny Q's Avatar
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    My 2002 w/17K miles failed

    15 mph HC Max 50 Average 4 Measured 75
    25 mph HC Max 34 Average 4 Measured 34

    I took it back for a retest a couple weeks later. I warmed it up more this time. Results were much lower.

    15 mph HC Max 50 Average 4 Measured 17
    25 mph HC Max 34 Average 4 Measured 14
    2002 Silver/Black

  23. #23
    Yes, the cats have to be HOT to get thru smog tests.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  24. #24
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    Quote Originally Posted by Z8doc View Post
    Vanos problem noted on the earlier models of the Z8 be the problem?
    VANOS is same for all production years, accumulator was the difference - and if you've had your vanos replaced likely you have updated solenoid boards and the accumulator retrofited

    here's a failed CA smog - engine ran rich as a result of vanos consumables

    http://www.m5board.com/vbulletin/e39...ons-twist.html

  25. #25
    Administrator thegunguy's Avatar
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    Passed today. Drove ~40 mins to make sure everything was warm.

    20,700 miles
    15mph %CO2 14.5, HC (Avg 4, Meas 18), CO2 (Avg 0.01, Meas 0.01), NO (Avg 27, Meas 0)
    25mph %CO2 14.5, HC (Avg 4, Meas 15), CO2 (Avg 0.01, Meas 0.01), NO (Avg 26, Meas 0)
    thegunguy

  26. #26
    Passed the biannual CA smog check today!

    39,XXX miles
    15mph %CO2 14.3, HC (Avg 4, Meas 50), CO2 (Avg 0.01, Meas 0.03), NO (Avg 27, Meas 0)
    25mph %CO2 14.3, HC (Avg 4, Meas 28), CO2 (Avg 0.01, Meas 0.03), NO (Avg 26, Meas 0)
    My Best,

    Ed

    2002 Z8 Jet Black//Sport Red
    2012 SLS AMG Obsidian Black/Classic Red

  27. #27
    Z8Mania
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    Nice! Well done!

  28. #28
    I'll just take credit for the board's advice to ensure the engine and cats are at operating temperature before the test and my recent replacement of the air cleaner filters. For an OEM car like mine, I would have been surprised if it had not passed.

    I had the testing done at PPBMW, and I enjoyed catching up with Matt while there.
    My Best,

    Ed

    2002 Z8 Jet Black//Sport Red
    2012 SLS AMG Obsidian Black/Classic Red