+ Reply to Thread
Page 1 of 2
1 2 LastLast
Results 1 to 10 of 14

Thread: Emissions help

  1. Join Date
    Jun 2004
    Posts
    15
    Downloads
    0
    Uploads
    0

    Emissions help

    I read the emissions thread, but it didn't really help with my issue(or I suck at reading that graph). My car passed good on HC and NOx, but failed on CO. The actual reading was 40.3623 where the limit is 20.0000. I need to know what would cause the CO to be high. I tested with the SAFC zeroed out(stock settings), should I have tried with the tuned settings? The previous owner told me he passed with the afc zeroed out, thats why I tried. I have no previous experience with the AFC so I'm not sure if what I did is right or not.

    Also, not sure if its totally important but mods are: small 16g turbo, hard upper ic pipe, hks ssqv mounted blow through, gm maf w/translator, hard intake pipe with cone filter, SAFC-II, act 2600 clutch. Its a 1990 GSX.

    Thanks for any help. I greatly appreciate it.

    -Kaleb

  2. Join Date
    Mar 2002
    Location
    Elizabeth
    Posts
    1,814
    Downloads
    1
    Uploads
    0

    You are still running rich. A good catalytic converter will take the HC reading down significantly.

    What exactly did you zero out? everything?
    I would take some more out of the low and high throttle settings.
    You can see in the emmisions graph that the only way you can have high CO is from running richer the 14.7:1
    -Seth

    2007 - 11.671 @ 125.34 50trim, 100shot, 110 octane
    2009 - 11.283 @ 126.86 SC6152e (131.11 best trap), only boost

    The Pictures
    Other forum screen names; awd1990dsm

  3. Join Date
    Jun 2004
    Posts
    15
    Downloads
    0
    Uploads
    0

    There are two settings in the SAFC. The first one is the "tuned" map, the second is completely stock settings, everything zeroed. My HC and NOx were fine, just the CO was high.

    the HC reading was 2.4451 limit 3.0000
    the NOx reading was 2.3150 limit 6.0000

    edit: I think the car also has a walbro fuel pump. Not sure which one. Or maybe the stock pump is just really loud.

  4. Join Date
    Feb 2003
    Location
    CO
    Posts
    483
    Downloads
    0
    Uploads
    0

    I had trouble passing with my stroker, I ended up just disconnecting the wastegate arm (so they couldn't get into boost) and leaning it out about 20%. Also, it can't hurt to put a small washer between your exhaust pipe and cat (just after the cat). This little trick worked wonders for a friend!

    Good luck!

  5. Join Date
    Sep 2003
    Location
    Boulder, CO
    Posts
    559
    Downloads
    0
    Uploads
    0

    Why don't you guys just tune your cars better? I passed with my 92 when it was literally blowing smoke on the rollers which should be an automatic fail. CO was 19.xx with the blue smoke. AFC and datalogger were the only mods.

    Sea foam the motor before the test and get the cat as hot as possible. Do not turn off the car in the line like they ask, just keep that cat nice and hot.

    If your fuel system is up to the task, I'd consider a tune with some E85; the oxygen in the alcohol helps reduce CO emissions.

    There is no special trick to make you pass; all the fast guys here are street legal and have passed the roller test, just tune the damn car!
    '90 GS Turbo

  6. Join Date
    Jun 2004
    Posts
    15
    Downloads
    0
    Uploads
    0

    Quote Originally Posted by KeltonDSMer
    Why don't you guys just tune your cars better? I passed with my 92 when it was literally blowing smoke on the rollers which should be an automatic fail. CO was 19.xx with the blue smoke. AFC and datalogger were the only mods.

    Sea foam the motor before the test and get the cat as hot as possible. Do not turn off the car in the line like they ask, just keep that cat nice and hot.

    If your fuel system is up to the task, I'd consider a tune with some E85; the oxygen in the alcohol helps reduce CO emissions.

    There is no special trick to make you pass; all the fast guys here are street legal and have passed the roller test, just tune the damn car!

    I would tune the damn car if I knew what the hell I was doing. It really doesn't make sense to me that the HC and NOx were fine but the CO was so far off. Especially if high CO has to do with being rich. Seems to me that would make the HC high too.

  7. Join Date
    Sep 2003
    Location
    Boulder, CO
    Posts
    559
    Downloads
    0
    Uploads
    0

    CO isn't necessarily caused from being rich, it is from incomplete combustion. What condition is your ignition system in? Are your pugs and wires okay? What do the plugs look like?
    '90 GS Turbo

  8. Join Date
    Feb 2005
    Location
    Littleton, CO
    Posts
    148
    Downloads
    0
    Uploads
    0

    High CO levels are also caused by a vehicle that's burning oil. That's why my Dodge wouldn't pass a month ago; I had a leaking intake manifold gasket which caused it to burn oil. You could smell the burning oil when you drove.

    So, it's possible that you've got a gasket somewhere that's leaking oil and the oil is getting burned.

    Also, if you have a 255 pump, but no FPR, you could also be running rich because of that.

  9. Join Date
    Mar 2002
    Location
    Elizabeth
    Posts
    1,814
    Downloads
    1
    Uploads
    0

    Quote Originally Posted by Dark_Horse
    Also, if you have a 255 pump, but no FPR, you could also be running rich because of that.
    That can be tuned out so its a non issue though.

    I have a 255 and no FPR. My fuel pressure at idle with the line connected is 40psi. My car fast passed.

    For most people, failing emmisions should shed light on how you suck at tuning or have a crappy tuning device. However, with this case, seems like something is mechanically wrong ie(burning oil maybe).

    I would spend some time on google and find out what could make you have high CO.
    -Seth

    2007 - 11.671 @ 125.34 50trim, 100shot, 110 octane
    2009 - 11.283 @ 126.86 SC6152e (131.11 best trap), only boost

    The Pictures
    Other forum screen names; awd1990dsm

  10. Join Date
    Sep 2003
    Location
    Boulder, CO
    Posts
    559
    Downloads
    0
    Uploads
    0

    I am not the best tuner, have a sub-par tuning device (AFC) and also burn oil; I passed with less than 10 parts CO.

    Due to the fact that the NOx and HC is within spec, I would say check the ignition.

    Another way to make it (if you are careful) is to use lower octane fuel just for the test. 87 will burn very easily compared to the 91 and will combust more completely (that means less CO). Obviously you have to not go into much boost with the mid-grade fuel, but it does reduce emissions.
    '90 GS Turbo

+ Reply to Thread

Posting Permissions

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