Page 1 of 2 12 LastLast
Results 1 to 25 of 38

Thread: Smog woes - HC

  1. #1
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002

    Smog woes - HC

    I'm having a hell of a time getting my 96 m3 passed california smog. It's reading really high HC and it smells rich. I've done a ton of work... New front o2's, clean and rebuild injectors, replace pcv system, new plugs, resealed vanos. I'm stumped.

    CO and NO are fine. Coincidentally this last test read high NO for some reason but the last two fails it was only HC.

    It's not throwing any codes. What software do people use to get detail on what the fueling is doing? I use TorqueLite on my phone with a cheap wireless obd2 adapter.

  2. #2
    Join Date
    Jun 2009
    Location
    McKean township Pennsylva
    Posts
    10,519
    My Cars
    1999 M3 , 1999 328is
    Rom Raider is a great software for tuning the ECU on the obd2 M52/S52 engines. It's quite inexpensive, needing just the correct USB to OBD adapter and a flashing program.

    https://sites.google.com/site/openms...with-romraider

  3. #3
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    51,754
    My Cars
    11/88 E32 750iL+98 E36M3
    maybe you try Cataclean, here the results of an 1988 E32 750 M70 in CA which first did not pass the smog test, then the inspector recommended Cataclean and then he passed, here the results before and after: Final -- Passed smog check , The HC reading dropped more than 50%, from 103 down to 46 PPM! NO reading also dropped more than 50%^ although those were below MAX anyway. I've never thought that those "guarantee to pass" products can deliver but this Cataclean actually works!
    ASM Emission Test Result http://www.bimmerboard.com/forums/posts/1272578
    ad says:Using Cataclean can lower your total hydrocarbon emissions by up to 50 percent.Reduces carbon build-up in catalytic converter, oxygen sensors, fuel injectors and cylinder heads which results in improved fuel efficiency.Improves overall vehicle performance-including driveability issues such as power reduction, hesitation, rough idle, hard starts and lost fuel economy
    Last edited by shogun; 05-01-2021 at 10:59 PM.
    Shogun tricks and tips for the E32 series http://twrite.org/shogunnew/topmenu.html

  4. #4
    Join Date
    Sep 2008
    Location
    CA
    Posts
    56
    My Cars
    99 E36 M3, 95 E36 Vert
    Second on catalytic issues. Youve done evrything else.

    98 M3 same issue 2 yrs ago, did what you did; bit the bullet and spent the $400 out the door to weld 2 new cats (theres a LOT of smog places that dont care about welded cats; not so much more ppl still willing to cheat system). Passed 2 yrs ago, and still passed this past Dec 2020. No mods except oil change, new plugs, and lucasoil fuel clean before this last smog.

    Friendly reminder of running 25 miles before smog and let the car run while waiting in line at the smog, and OEM airbox use.

    Good luck, if you wanna sell the car i'll take it for free......

    .........

    ......
    ...
    ..
    .

  5. #5
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    Wouldn't cats mean high NOX?

    I think I found something to chase. I checked the o2 sensors and the heater circuit is only reading 9v. The book says it's supposed to be battery voltage. Could be a bad ground or relay causing the sensor to not get hot enough causing it to not read right... Tbd.

  6. #6
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    51,754
    My Cars
    11/88 E32 750iL+98 E36M3
    Here copied from Bosch website: 5 Gas Analysis - Bosch Technologies Group
    Three Reasons for Gas Analysis
    * Identify engine performance and mechanical problems
    * Test the running efficiency of the engine
    * Test for exhaust emissions against state and federal standards

    Combustion Chemistry and Gas Analysis.

    * The combustion process releases the energy stored in the fuel
    * Fuels consist basically of carbon(C) and hydrogen(H) referred to as hydrocarbons (HC).
    * Under ideal conditions all of the HCs would be converted to H2O, CO2 and heat.

    Combustion Chemistry and Gas Analysis.
    * Unfortunately this complete combustion is rarely if ever achieved
    * Short burn times, continuously changing mixture ratios and air temperatures, and combustion chamber quenching produce conditions which give rise to the formation of pollutants

    Pollutants
    * Incomplete combustion produces carbon monoxide (CO)
    * Unburned fuel produces hydrocarbons (HC)
    * High combustion temperatures produce oxides of nitrogen (NOX)

    Other Exhaust Gases
    * Carbon dioxide (CO2) is a product of complete combustion. Therefore the higher the level of CO2 the more efficient the engine is running.
    * Oxygen (O2) level in the exhaust indicates the fuel-air mixture.

    High O2=lean
    Low O2=Rich

    Gas Analysis as a Diagnostic Tool

    Gas analysis

    * Is a quick and accurate way to determine the running conditions of an engine
    * By observing the 5 gas readings and understanding their relationship to each other you can diagnose the 3 major engine areas:
    Fuel delivery
    Ignition
    Engine Mechanics

    High HC Only
    Hydrocarbons are unburned fuel. This can be caused by:
    Ignition Timing (base and advance)
    Vacuum Leaks (hoses, brake booster, manifold, evap. etc.)
    Ignition (misfires, coil breakdown, etc.)
    Mechanical (low compression, bad cam, etc.)
    Catalytic Converter Failures

    High CO Only
    * Carbon Monoxide is a result of incorrect fuel/air mixtures. Causes include:
    * For Carburetors (float level, power circuit, choke circuit)
    * For Injection (injectors, pressure regulator, temp sensor, MAP/MAF sensor)
    * For Both Systems (air filter, PCV, Evap, O2 sensor, air injection

    High Nox Only
    * NOX is caused by high combustion chamber temperatures. Check:
    * EGR (valve, controls, solenoids, passages, vacuum hoses)
    * Ignition Timing ( base and advance)
    * Engine Temperature (cooling system, fan restricted exhaust, Thermostat)
    * Vacuum Leaks (hoses, booster, evap, etc)
    * Mechanical (carbon deposits, converter, etc)

    High CO and HC
    * Normally, when HC and CO are high it is the result of a CO failure driving the HC high.
    * Correct for high CO first (Excessive fuel, restricted air, Evap., etc.)
    * If HC is still high, test as high HC (ignition, timing, mechanical, etc.)

    High CO and Nox
    * These problems are normally incompatible. If they occur on the same test they will most likely occur at different points on the drive cycle
    * Correct CO failure first
    * Retest and locate NOX failure in drive cycle and correct as NOX failure only

    HC and NoX
    * High HC and NOX normally occur as the result of a lean misfire. Check for:
    * Lean run (vacuum leaks, mixture problems, fuel delivery, etc.)
    * Mechanical (oil burning can cause high combustion chamber temperatures)

    CO, HC and NOX
    * This is a complete breakdown of the emission systems or multiple failures. Check:
    * Catalytic Converter (missing, damaged)
    * PCM (closed loop, wiring, etc.)
    * Drive cycle ( if failures occur at different points diagnose each failure separately)
    Shogun tricks and tips for the E32 series http://twrite.org/shogunnew/topmenu.html

  7. #7
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    This is awesome, thanks!

  8. #8
    Join Date
    Nov 2002
    Location
    Washington, DC
    Posts
    6,448
    My Cars
    E30 E36 E46 E90
    Can you post your actual results?

    Have you confirmed that your engine DME temperature sensor is reading correctly? Note that DME temp is separate from gauge temp. If the DME thinks the engine is cold, it'll keep the car rich / open loop.

    If you are just rich, you may be able to use some E85 to make the car read leaner. Note that a few gallons of E85 will lower HC, but raise NO.
    2011 M3 Sedan
    2006 GMC Sierra 2500HD LBZ
    1999 323i GTS2
    1995 M3 - S50B32/S6S420G/3.91
    1990 325is
    1989 M3 - S54B32/GS6-37BZ

    Hers: 1996 Porsche 911 Turbo
    Hers: 1989 325iX


  9. #9
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    Sure I'll post up my numbers after work. I replaced the engine temp sensor. The one in the head near the oil filter housing. I tested it against the original one and they read slightly different but not too far off.

    What do you think about my theory of the o2 sensor not getting enough voltage and thus not reading correct? Battery reads 14v when running but the heater circuit is only reading 9v.

  10. #10
    Join Date
    Jan 2021
    Location
    Virginia
    Posts
    94
    My Cars
    1999 323i convertible
    I drove a Saab 900 turbo convertible from VA to CA, that had a 2.5" exhaust system done on it with a high-flow cat. Went to get it smogged, and it failed spectacularly, can't remember which part of the test though. I went to an exhaust shop the next town over, asked them to replace the non-CA cat with a CA-only cat. At first, they didn't want to do it because it had a larger diameter exhaust than stock. They worded the invoice a different way, replaced the out-of-state cat with a CA-only cat, drove back to the testing station, and it passed with flying colors...
    Robert
    1999 323i E36 convertible (black, black top, tan interior)
    Newport News, VA

  11. #11
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    Attaching my two latest reports. The one with the black X was done a month ago and failed just HC. The other one was last week and I changed out the PCV system, Coolant temp sensor and ran super thin oil... I usually run 10w60 but tried 5w40 to see if the thinner oil would reduce some load on the engine... somehow it failed NO after that work?? After all the work I've done over the last few months the engine sounds so much smoother and the numbers had been dropping until this last test.

    Also odd, the earlier reports listed the car as n Automatic. I looked at previous years and it had that too. The new shop I tried last week said it was all jacked up in the system and switched it to manual BUT also insisted the car is a 2.8L. I argued with him that it's a 3.2L S52 but he insisted that the black smog label on the strut tower says to test it as a 2.8L, even after I pointed to the print on the label stating the car was ~3200cc's. I don't know if it matters... the Max allowable numbers are the same on both reports.
    Attached Images Attached Images

  12. #12
    Join Date
    Jul 2008
    Location
    Orange County
    Posts
    128
    My Cars
    -1997 Arctic/Dove M3
    Quote Originally Posted by GetOuttaMyWay View Post
    Attaching my two latest reports. The one with the black X was done a month ago and failed just HC. The other one was last week and I changed out the PCV system, Coolant temp sensor and ran super thin oil... I usually run 10w60 but tried 5w40 to see if the thinner oil would reduce some load on the engine... somehow it failed NO after that work?? After all the work I've done over the last few months the engine sounds so much smoother and the numbers had been dropping until this last test.

    Also odd, the earlier reports listed the car as n Automatic. I looked at previous years and it had that too. The new shop I tried last week said it was all jacked up in the system and switched it to manual BUT also insisted the car is a 2.8L. I argued with him that it's a 3.2L S52 but he insisted that the black smog label on the strut tower says to test it as a 2.8L, even after I pointed to the print on the label stating the car was ~3200cc's. I don't know if it matters... the Max allowable numbers are the same on both reports.

    I had this as well! The smog guy was such a dumbass.
    -1997 Arctic/Dove M3 Coupé-

  13. #13
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    I wonder if that affects how much load the dyno creates? I'm really curious.

    Update- I fixed the electrical issue to the o2 sensor heater and my Numbers as way better. Just barely failed the last test. I also ran a gallon of e85 mixed in with a 3/4 tank, not sure if that affected things. New tech also said I could try the CataClean and thought it might get me over the passing line.

  14. #14
    Join Date
    Nov 2002
    Location
    Washington, DC
    Posts
    6,448
    My Cars
    E30 E36 E46 E90
    Quote Originally Posted by GetOuttaMyWay View Post
    I wonder if that affects how much load the dyno creates? I'm really curious.

    Update- I fixed the electrical issue to the o2 sensor heater and my Numbers as way better. Just barely failed the last test. I also ran a gallon of e85 mixed in with a 3/4 tank, not sure if that affected things. New tech also said I could try the CataClean and thought it might get me over the passing line.
    What were your numbers? IIRC, the tipping point for alcohol is around E30, so you've got a decent bit more margin to keep adding if you're still failing on HC.
    2011 M3 Sedan
    2006 GMC Sierra 2500HD LBZ
    1999 323i GTS2
    1995 M3 - S50B32/S6S420G/3.91
    1990 325is
    1989 M3 - S54B32/GS6-37BZ

    Hers: 1996 Porsche 911 Turbo
    Hers: 1989 325iX


  15. #15
    Join Date
    Jun 2009
    Location
    Earth
    Posts
    2,656
    My Cars
    E34 M5, E36 M3, E90 M3
    Did you drive the car a lot before the smog test? The car needs to go onto the rollers immediately, if you let the car sit for more than a few minutes then the cats will cool down. Ideally, the smog tech should run the car on the rollers without a probe to ensure the cats are piping hot and I guarantee your car will pass. If you need a competent smog shop that understands this, LMK, I have a great recommendation for a smog shop in Berkeley hills.

    This sounds goofy, but remove the air filter and ask the tech to place a fan in front of the engine. This helped me lower HC's on my 98 M3 which had horrible oil consumption (1qt every 50-100 miles) and it worked.

    BTW adding a little E85 or alcohol to the tank absolutely helps lower HC's. Drive the car like an absolute mad man next time you smog it, I cannot emphasize this enough, the cats need to be really hot,

  16. #16
    Join Date
    Feb 2006
    Location
    In da OC
    Posts
    785
    My Cars
    1997 M3, 2021 330e
    Quote Originally Posted by Johal E32 View Post
    Drive the car like an absolute mad man next time you smog it, I cannot emphasize this enough, the cats need to be really hot,
    Yup, I light my badboy up every time before a smog check, redlining in 2nd gear on the fwy the whole way there for about 20 minutes. Has passed with flying colors every time!

    One of the last remaining members of the E36 M3 original owners club...a dying breed indeed.

  17. #17
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    Quote Originally Posted by nick325xit 5spd View Post
    What were your numbers? IIRC, the tipping point for alcohol is around E30, so you've got a decent bit more margin to keep adding if you're still failing on HC.
    Attaching here. High on HC @15mph, everything else looks great. The tech said if I get new cats it will def past, or I could try that CataClean stuff someone else on here recommended as well. Debating about biting the bullet and getting new cats... or trying the snake oil and some more e85. So close compared to where it was before...

    I took it for a good romp on the hwy, definitely hit 100 a few times. It sat idling at the shop longer than I would have liked but it was definitely up to temp and I fixed the 02 sensor heater issue so everything should have been up to temp.
    Attached Images Attached Images

  18. #18
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    Let me know what shop you like. The last shop I went to is the one on San Pablo near Alcatraz. I've gone there off and on over the years, usually the techs are really good but a few years ago they had a guy who didn't know how to use a timing light so I started using a shop on Broadway. Dude in there last weekend knew his shit and was very professional. There used to be a tech who was all up in the bimmer forums but he moved on.

    Also, since your local let me know if you know a good shop to get new cats put in, considering going that route since that's probably the issue now that I've sorted everything else out. Car just hit 200k and they're original cats so it's gotta be time...

    Yup, my usual routine is a solid rip through Redwood to get everything piping hot...

  19. #19
    Join Date
    May 2004
    Location
    SoCal
    Posts
    57
    My Cars
    98 M3, 09 Scion xB
    If you’re so close to passing have you to tried setting your tire pressure higher? I set mine to the max weight pressure ~44 psi (see door card) every time I go in for smog.

  20. #20
    Join Date
    Nov 2002
    Location
    Washington, DC
    Posts
    6,448
    My Cars
    E30 E36 E46 E90
    Quote Originally Posted by GetOuttaMyWay View Post
    Attaching here. High on HC @15mph, everything else looks great. The tech said if I get new cats it will def past, or I could try that CataClean stuff someone else on here recommended as well. Debating about biting the bullet and getting new cats... or trying the snake oil and some more e85. So close compared to where it was before...

    I took it for a good romp on the hwy, definitely hit 100 a few times. It sat idling at the shop longer than I would have liked but it was definitely up to temp and I fixed the 02 sensor heater issue so everything should have been up to temp.
    You've got lots of room on NO. Add a couple gallons more E85. Get it hot. Air up your tires.

    If you still have the original cat, you may consider cleaning it with citric acid before the next inspection season. I don't encourage new aftermarket cats because that puts you on a likely "buy a new cat every couple of years" bicycle.
    2011 M3 Sedan
    2006 GMC Sierra 2500HD LBZ
    1999 323i GTS2
    1995 M3 - S50B32/S6S420G/3.91
    1990 325is
    1989 M3 - S54B32/GS6-37BZ

    Hers: 1996 Porsche 911 Turbo
    Hers: 1989 325iX


  21. #21
    Join Date
    Jul 2004
    Location
    sf bay area
    Posts
    77
    My Cars
    99M3 Convertible
    I don't think you need new cats. I've been on the border of not passing on HC's for a while and I only have 68k miles. If you want to drive to Newark go to MT Smog. I just went and the guy is good. He knows BMW's are finicky with getting the cats hot. He ran the car on the dyno for a good 20-30min beforehand and it passed with the best margin in a while.
    Last edited by ax77; 05-12-2021 at 10:24 AM.

  22. #22
    Join Date
    Oct 2005
    Location
    Tracy, CA
    Posts
    665
    My Cars
    e46 325XI, e36 M3
    Quote Originally Posted by ax77 View Post
    I don't think you need new cats. I've been on the border of not passing on HC's for a while and I only have 68k miles. If you want to drive to Newark go to MT Smog. I just went and the guy is good. He knows BMW's are finicky with getting the cats hot. He ran the car on the dyno for a good 20-30min beforehand and it passed with the best margin in a while.
    Yup totally agree Tom has always smogged my 95 m3 and new immediately how to work it.

  23. #23
    Join Date
    Jun 2009
    Location
    Earth
    Posts
    2,656
    My Cars
    E34 M5, E36 M3, E90 M3
    I agree with Nick, you have lots of room on the NO. New cats will certainly get you passed, but I guarantee you will need to replace those aftermarket cats every few years.

    7 days a week Smog on San Pablo used to be my go-to, until they changed ownership and they jacked the prices WAY up.

    My usual spot is https://www.yelp.com/biz/4-less-smog-check-berkeley-5

  24. #24
    Join Date
    Jul 2004
    Location
    sf bay area
    Posts
    77
    My Cars
    99M3 Convertible
    just as a side vent. Why did they choose to make 2000 the cutoff for the new smog test? It really pisses me off that here in Ca we have to worry every two years whether we'll barely pass or not. What's the difference between a 1999 and a 2000? They're all obd2. Maybe someone here knows but it seems arbitrary to me. Should have been all obd2 cars get the new test.

    also yeah, aftermarket cats are garbage and won't last more than about 4 years.

  25. #25
    Join Date
    Sep 2006
    Location
    Oakland, CA
    Posts
    126
    My Cars
    1974 BMW 2002
    Problem is my tags are way out, I can't drive into berkley I get pulled over if my windshield is dirty lol.

    I'll try more ethanol. CataClean or nah?

Page 1 of 2 12 LastLast

Similar Threads

  1. [SMOG] High HC @Idle question
    By religi0n in forum 1991 - 1999 (E36)
    Replies: 0
    Last Post: 03-07-2012, 07:18 PM
  2. Failed smog, High HC at idle; drive HC good.
    By dmcwheat in forum 1983 - 1991 (E30)
    Replies: 7
    Last Post: 07-26-2010, 08:52 PM
  3. failed smog, high HC at idle (pic)
    By AMDdude in forum 1991 - 1999 (E36)
    Replies: 22
    Last Post: 01-02-2009, 10:39 PM
  4. Need Advice: Failed Smog High HC & Nox
    By Gordon@EDGE in forum General BMW and Automotive Discussion sponsored by Intercity Lines
    Replies: 16
    Last Post: 10-11-2007, 10:18 AM
  5. Smog woes in SoCal...
    By euroautowerks in forum California sponsored by Avus Autosport
    Replies: 1
    Last Post: 10-19-2004, 04:33 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •