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SMOG Fail, SOLVED

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    SMOG Fail, SOLVED

    Honestly, I am damn surprised that I am even in the ballpark of passing numbers, so I HOPE that getting to pass will not be too much of a pain. The car has a 2.1L M42 built by Metric Mechanic with all of the bells and whistles. I was thinking that I would see NOx go through the roof with the 11.5:1 compression, but it didn't. In fact, I was only failing HC and CO emissions.

    I ran the car for about 1000 miles with the wrong injectors and was running RICH, like black smoke at WOT. So it is seeming highly likely that the cat that I installed in 2009 is pretty dead. The car was running a bit rich in 2010 as well due to me tuning my wide-band wrong lol. Hell, the O2 sensor might be clonked too thanks to that since I replaced it at the same time as the cat in 2009.

    In 2009, I passed SMOG with flying colors. Probably because I had a new cat installed and then drove straight to the test station. In 2011, I passed on the first try too, but my HC and NOx numbers had definitely increased. This year, here are the numbers from the first run:

    15 MPH:
    CO2: 14.15%
    O2: 0%
    HC: 135ppm (124ppm limit) FAIL
    CO: 0.64% (0.78% limit)
    NO: 429ppm (815ppm limit)

    25 MPH:
    CO2: 13.89%
    O2: 0%
    HC: 131ppm (98ppm limit) FAIL
    CO: 0.96% (0.66% limit) FAIL
    NO: 311ppm (754ppm limit)

    I have a new Bosch LSU 4.2 wide band O2 sensor on the way and am getting a new Magnaflow cat put in tomorrow afternoon. Actually, I think that I am going to postpone the cat install until the new O2 sensor comes since the car is running rich, and rich running = cat death. Since the engine is basically new, there aren't any concerns on my end about carbon build up or plugged injectors since those are new too. As of now, I am suspecting that maybe the O2 is the main culprit here since, according to the calculator in the link below, my AFR's are 14.36 and 14.22. The ECU should be in open-loop mode and using the O2 sensor to maintain 14.7ish, so the sensor may well be fucked.


    Will keep folks updated. Any thoughts?
    Last edited by bmwman91; 08-28-2013, 09:47 AM.

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    #2
    Your cat looks good there (NOx) but your HC and CO are both high. You are still running rich...lean it out a bit. NOx levels will go up but you are well below the limit so you can afford it.

    Is the engine broken in?
    "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

    85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
    88 M3 - LACHSSILBER/SCHWARZE
    89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
    91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

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      #3
      Yeah, I am thinking that my best bet is to swap a fresh O2 sensor in and make SURE that I am running at stoichiometric. Thankfully, the LC-1 system in there allows me to tweak that. If I fail again, I can always take it behind the SMOG station, hook up my laptop and go back in.
      "What did you do to make it suddenly pass?"
      "Oh, it is my wife's car. I just went to the bathroom. Is my turn signal fluid looking OK?"

      The exhaust has a bit of a sulfur'y smell at idle right now. I assume that I shouldn't smell much of anything if the mixture is right?

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        #4
        I was going to ask....if you run an LC1 make sure you free air calibrate the sensor every 6 months or whatever it is. It is critical for correct operation. It's easy to set it and forget it. In fact, I need to do mine.
        "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

        85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
        88 M3 - LACHSSILBER/SCHWARZE
        89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
        91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

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          #5
          Interesting. So I take it that the calibration drifts? I think that I recalibrated it a couple of months ago when I fired up the new engine, but I can't recall exactly. Years of running rich probably have not done me many favors.

          The LC-1 is a finicky beast to get installed properly too. You seen my install write-up?http://www.r3vlimited.com/board/showthread.php?t=248489

          Also, here are my smog numbers from 2009. My NOx passes now, but it is a bit higher than it was! Then again, these results were from an internally stock M42 with 200k miles, and the car now has a 2.1L M42 with high compression and hot cams lol. I wish I knew where my 2011 results went...
          Last edited by bmwman91; 08-20-2013, 04:19 PM.

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            #6
            So I went and messed with my LC-1 for a bit. It seems as though output 1 is dead or malfunctioning. At idle and 2000RPM I was seeing an average AFR of ~14.2. After adjusting things so that the ECU would target an AFR of 15.4, there was very little change. The average AFR was maybe 14.6.

            So, I connected output 2 from the LC-1 to the ECU and set it to stock configuration (14.7 AFR at 0.45V). Voila, suddenly I am running at stoichiometric again. Maybe a little rich, but there is LTFT (long term fuel trim) that will take an hour or so of driving to un-learn. The car ran better in general too. So, I am still replacing the sensor since rich running is bad for them, but I bet that my HC numbers will have improved a lot.

            The LC-1 seems to be a temperamental biotch. A DAC output crapped out on my back in 2006 or so too and Innovate replaced it. It's annoying as hell to have this happen though. I wonder if it has been slowly dying for the last year or two, which might explain the slow degradation of this car's fuel economy that nothing seemed to correct.

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              #7
              apparently they do drift. sounds like u found the problem. i'd bet that was the cause of the richness.
              "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

              85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
              88 M3 - LACHSSILBER/SCHWARZE
              89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
              91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

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                #8
                Yeah, not just a drift, but it looks like one of the LC-1 outputs is broken. I need to get my portable oscilloscope in there to see what the output voltage waveform looks like.

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                  #9
                  what kind of CAT is on there now? is it a magnaflow high flow CAT? if so, those things are barely good for 2 yrs. I have to replace them everytime i smog.
                  IG: @Baye30

                  FRONT VALENCE IS ZENDER!!! STOP FILLING MY PM BOX PPL!!!

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                    #10
                    Yeah, Magnaflow. The exhaust shop guy and I were talking and he said that E30's (and E36's to a similar degree) burn through cat's pretty fast since they have a tendency to run rich when basically anything is wrong with them. He recommended Magnaflow over Catco because supposedly Magnaflow has more exotic metal in the core which is better for SMOG. My old one showed definite signs of overheating as the outer steel shell was discolored purple/amber in spots. He said that discoloration like that is a classic sign of a messed up AFR...which was exactly the case.

                    I passed SMOG with flying colors today. Here is what I did prior to that.

                    1) Last week: Found that my LC-1 WBO2 controller's analog out #1 was not functioning, so I switched to output #2. That caused an immediate improvement of my AFR, from ~14.2 to ~14.7. So there is the root-cause of the issue. Honestly, I probably could have passed just doing this.

                    2) Today: Replaced the O2 sensor (Bosch LSU 4.2 wide-band).

                    3) Today: Had a new 3-way cat installed.

                    Failing SMOG numbers:
                    15MPH
                    CO2 %: 14.15
                    O2 %: 0.00
                    HC PPM: 135 (FAIL)
                    CO %: 0.64
                    NO PPM: 429

                    25MPH
                    CO2 %: 13.89
                    O2 %: 0.00
                    HC PPM: 131 (FAIL)
                    CO %: 0.96 (FAIL)
                    NO PPM: 311

                    Today's passing SMOG numbers:
                    15MPH
                    CO2 %: 14.52
                    O2 %: 0.00
                    HC PPM: 19
                    CO %: 0.04
                    NO PPM: 46

                    25MPH
                    CO2 %: 14.50
                    O2 %: 0.00
                    HC PPM: 17
                    CO %: 0.06
                    NO PPM: 47

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