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Thread: 1999 M3 not passing smog, no codes. High hydrocarbons

  1. #26
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    Can bad ignition coil cause high hydrocarbons? no check engine light

    I recently tried to smog my car and failed (3 attempts) NO CHECK ENGINE LIGHT OR CODES

    I just got the car and here are the things i did before i smogged it.

    Car has 129k miles and its a 1999 M3

    seafoam in gas tank + through brake booster vacuum line let it sit in hot engine and got alot of black smoke.

    changed sparked plugs

    changed oil (doesnt really make a difference)

    changed air filter

    Here were my first results at my smog attempt:

    15mph ..... HC (PPM) came out to 147 .... max is 54 *fail*
    25mph...... HC (PPM) came out to 33 ...... max is 37 *pass*


    2nd attempt was me not really changing anything but getting the engine super hot driving hard and idling and revving for about 15 min before smog:


    Here were my results the 2nd time :

    15mph......HC (PPM) came out to 83 .... max is 54 *fail*
    25mph......HC (ppm) came out to 31..... max is 37 *pass*


    3rd attempt I visually inspected the car furthermore and found a hole in the intake boot near hole that leads to ICV.

    Replaced intake boot

    Cleaned ICV

    Cleaned MAF sensor

    Changed Fuel Filter

    This time i got the engine super hot! idled on about 3k rpm for about 15 min right before smog.

    Here were my last results :

    15mph.......HC (PPM) came out to 157..... max is 54 *fail* even higher than the first time.
    25mph.......HC (PPM) came out to 31.......max is 37 *pass*


    So heres what I had in mind,


    The car eventually reaches its operating temp ( needle in middle) but seems like it takes a while to get there. Could a bad thermostat cause high hydrocarbons and nox?

    Also, a bmw tech told me it could possibly be the upstream (near head) o2 sensors lagging. I thought o2 sensors usually throw a code when they go bad but i could be wrong. Could this possibly be the culprit?

    Alot of people are telling me to get the liquid gtp (guaranteed to pass) from the local auto store but wanted to find the root cause of the issue. car averages about 19mpg.. normal?

    HELP

    UPDATE: I recently checked my ignition coils and alot of them look different. Some older than others... again... no check engine light but is there a way to see if some of the coils are bad ? Some of the spark plugs looked real oily as well.

  2. #27
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    Can bad ignition coil cause high hydrocarbons? no check engine light

    Coils can be tested for resistance, but they probably should all be of the same brand and configuration.
    Spark plugs and spark plug extenders should be fresh. Old spark plug extenders can leak voltage thru micro cracks in the rubber. Dry/hard extenders should be replaced. Make sure that the spark plugs are the correct brand and heat range - Bosch for OBDII, NGK for OBDI.

    Get the catalytic converter HOT before the test by driving, no stationary idling/reving.

    And yes the pre-catalytic converter O2 sensors that are getting old and slow to respond can be an issue and not set any codes till they fail. How old are yours, how many miles?

    Do you have any vacuum leaks, cracks in intake boot, dry crazed vacuum lines? How fresh is the valve cover gasket?


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    Last edited by bluptgm3; 11-08-2018 at 05:00 AM.

  3. #28
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    car has 130k miles, They are most likely the original sensors

  4. #29
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    S52 O2 sensors are said to be 100K mile replacement items. OE Bosch sensors are made by NTK.


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  5. #30
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  6. #31
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    "Can bad ignition coil cause high hydrocarbons? no check engine light"


    Is this really a serious question?

    This is as simple as I can put it: The engine is a pump. It pumps in fuel (hydrocarbons, by the way) and air, burns the combination, then pumps out what's left.

    If you don't burn it, the fuel/air gets pumped in and the fuel/air gets pumped right back out. Raw hydrocarbons. Unburned. In high concentrations.


    (I noticed this is the second thread for the same issue. Did we run out of parts or money?)
    Last edited by tjm3; 11-10-2018 at 04:04 PM.
    See ya later,

    tony
    '98 M3, '92 Dinan3, '05 R1100S BCR, '07 R1200S, Aprilia T

  7. #32
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    "The car eventually reaches its operating temp ( needle in middle) but seems like it takes a while to get there. Could a bad thermostat cause high hydrocarbons and nox? "

    Yes
    [IMG][/IMG]

  8. #33
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    An engine that is slow coming to temperature, you will likely see high hydrocarbon count.


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  9. #34
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    UPDATE:

    Just changed my thermostat and car drives a little better. I think I might be on to something here. Today I pulled up the livestream data on my scanner. I noticed the kg/h reading is around 0.02 on idle for the MAF. Is this normal? Maybe that explains why i'm not idling higher on cold starts and the car is running rich. I could be wrong..can someone tell me if that kg/h reading is normal? Or if they recommend replacing MAF sensor. 20181130_154139_1543631866650_resized.jpg

  10. #35
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    UPDATE:

    Just changed my thermostat and car drives a little better. I think I might be on to something here. Today I pulled up the livestream data on my scanner. I noticed the kg/h reading is around 0.02 on idle for the MAF. Is this normal? Maybe that explains why i'm not idling higher on cold starts and the car is running rich. I could be wrong..can someone tell me if that kg/h reading is normal? Or if they recommend replacing MAF sensor.

    - - - Updated - - -

    20181130_154139_1543631866650_resized.jpg

  11. #36
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    Anyone know the correct kg/h reading for a 1999 BMW M3 on idle?

    20181130_154139_1543631866650_resized.jpg Im thinking my Mass Air Flow Sensor is bad but dont know for sure. I hooked up my scantool and got a livestream data reading and my kg/h reading is 0.02 on idle. I have a 1999 BMW M3. There is no check engine light but I failed the 15mph nox emissions test. High hydrocarbons.

    Does anyone know the average kg/h on idle for 1999 m3? Help

  12. #37
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    I can get you a better number tomorrow, but I've got a tracker in my car that provides almost every readable parameter. Unfortunately, our first-gen OBD system isn't that fast so it only transmits every 30 seconds or so, so I don't have my reading at idle right before I shut the car off. (we're still working on it, but at the moment I can't go back and look at my history, though this should be fixed in a couple weeks). But I digress. I can start the car and let it idle a bit tomorrow to get you a number at idle.

    I was at 1059 rpm at 18% absolute throttle and got 3.64 g/s. That's not too far above idle / zero actual throttle.

    3.64 g/second * 60 seconds in a minute * 60 minutes in an hour / 1000 grams in a kg = 3.64*60*60 / 1000 = 13.104kg/hour.

    So the correct reading at idle (around 600 rpm or so) may be a LOT less than the 13kg I got at 1000 rpm, but I doubt it's as low as you're reading. That seems way too low, seems like your MAF is bad.

    Having said that... with no CEL and working cats and O2s, I wouldn't think you'd have high hydrocarbons just from being in open loop, but I haven't had that many problems so I'm not that knowledgeable.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  13. #38
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    Quote Originally Posted by dakar786 View Post
    20181130_154139_1543631866650_resized.jpg Im thinking my Mass Air Flow Sensor is bad but dont know for sure. I hooked up my scantool and got a livestream data reading and my kg/h reading is 0.02 on idle. I have a 1999 BMW M3. There is no check engine light but I failed the 15mph nox emissions test. High hydrocarbons.

    Does anyone know the average kg/h on idle for 1999 m3? Help
    I got 12.3 at idle (727 rpm, 11% load, and 17% absolute throttle position).

    Sounds like you might need a new MAF.

  14. #39
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    Also, do you guys recommend replacing with oem? Or aftermarket? Theres a big price difference. I am hearing mixed reviews. How big of a difference can it be?

  15. #40
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    When replacing sensors on your BMW, use only BMW, VDO or Siemens.

    Some offshore (Chinese) parts may be good, but there are many bad reports of bogus sensors.
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  16. #41
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    Quote Originally Posted by dakar786 View Post
    Also, do you guys recommend replacing with oem? Or aftermarket? Theres a big price difference. I am hearing mixed reviews. How big of a difference can it be?
    I'd add Bosch to the list, but yeah - I wouldn't cheap out on this.

  17. #42
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    Quote Originally Posted by dakar786 View Post
    does anyone recommend any hoses in the vacuum system to be changed? Hoses that might effect the high hydrocarbon reading ? theres a small hose that connects to the secondary air pump near the exhaust that i will change out. It is completely frail and almost completely warn out. Don't know if that might have an effect on it.
    Worth a shot but I don't think that hose is the issue. Have you hooked up the car to a scanner tool or recorded live data while driving? This can easily be done with a cheap scan tool or even bimmerlogger. As previously mentioned 19mpg seems low but could be correct depending on where/how you drive. May be worth cruising highway around 70mph. You should be close to 26mpg then...


    What happens when you disconnect maf?
    Last edited by bmw328m52; 12-06-2018 at 09:16 AM.

  18. #43
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    When I disconnect the maf it seems to not have a big difference. I can hear the rpm fluctuate for a sec but it drives normal with it disconnected. I'm still researching the correct kg/h reading and still haven't found anything yet. The kg/h doesnt go over the decimal even if i revv it. it stays between 0.02- 0.03. Do you know the proper reading? It doesn't seem right. I ordered a new maf sensor and hopefully that should fix it.

  19. #44
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    Quote Originally Posted by MauiM3Mania View Post
    When replacing sensors on your BMW, use only BMW, VDO or Siemens.

    Some offshore (Chinese) parts may be good, but there are many bad reports of bogus sensors.
    ^This.

  20. #45
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    UPDATE: I just got done installing my maf and the kg/h reading is the same. I ordered a oem (used) one that was supposedly tested in working condition. 0.02....... 0.03 when i revv it. i turned the car off hooked up my obd2 scanner and cleared the "adaptations". turned the car back on and the reading was the same. Does anyone recommend getting the 16 pin adapter that goes under the hood? What are the advantages of having that and hooking it up to my scanner? at this point im really confused and figuring out what the issue might be. Why is the reading of the different maf still the same ? and why is it soo low?

  21. #46
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    UPDATE: I just got done installing my maf and the kg/h reading is the same. I ordered a oem (used) one that was supposedly tested in working condition. 0.02....... 0.03 when i revv it. i turned the car off hooked up my obd2 scanner and cleared the "adaptations". turned the car back on and the reading was the same. Does anyone recommend getting the 16 pin adapter that goes under the hood? What are the advantages of having that and hooking it up to my scanner? at this point im really confused and figuring out what the issue might be. Why is the reading of the different maf still the same ? and why is it soo low?

  22. #47
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    UPDATE: I just got done installing my maf and the kg/h reading is the same. I ordered a oem (used) one that was supposedly tested in working condition. 0.02....... 0.03 when i revv it. i turned the car off hooked up my obd2 scanner and cleared the "adaptations". turned the car back on and the reading was the same. Does anyone recommend getting the 16 pin adapter that goes under the hood? What are the advantages of having that and hooking it up to my scanner? at this point im really confused and figuring out what the issue might be. Why is the reading of the different maf still the same ? and why is it soo low?

  23. #48
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    The “guaranteed to pass” SMOG products work and I would recommend that for you.

    I have a friend that does SMOG and he recommended that to me for a similar situation. The motor can be running right, but the cats are too “dirty” to clean efficiently. Those products essentially “clean” and restore what life the cats may have left in them (it can’t undo complete precious metal loss).

    BMW cats are very high quality and from my experience, respond well to this treatment. Try it. Follow the directions.

    https://www.oreillyauto.com/detail/b.../05063/4176075

    This is not the answer for poorly maintained engines needing work.

  24. #49
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  25. #50
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    Quote Originally Posted by Braymond141 View Post
    The “guaranteed to pass” SMOG products work and I would recommend that for you.
    I'll try some of that CRC stuff just for fun to see what it does to the emissions gas concentrations. My car would be perfect for that with 207,000 miles and a cat that last tested as 16 percent efficient AND passed CA smog last week with no mods or chems.
    Here the MSDS. Just solvents including polyether amines, same stuff they call Techron.
    Attached Files Attached Files
    Last edited by tjm3; 12-12-2018 at 08:22 PM.
    See ya later,

    tony
    '98 M3, '92 Dinan3, '05 R1100S BCR, '07 R1200S, Aprilia T

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