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Thread: Failed smog test

  1. #1

    Default Failed smog test

    Hi guys, I haven't been on here in a while but I am needing some help here. I took my car in to get it inspected and it failed smog test. The hc's were high. I think the norm is under 100ppm and I was at 300ppm on low and high speed test. I have replaced spark plugs, writes, O2 sensor and the cat is only 1 1/2 years old. I also checked my egr and it seems to be working. I cleared my codes to see if anything new comes up. I have also removed my charcoal canister to get more room in the engine bay but that shouldn't effect the test right? I've tried to give all the info I've got. Please help. Also it's a 94 with 180k on it.

    Strider
    '94 Miata "M Edition" - sold
    '99 Miata w/td05

  2. #2

    Default Failed smog test

    Put a bottle of heat in it and make sure it's warmed up really good before you take it in
    I'm not speeding officer, I'm qualifying!!!

    92 Red (sold)
    2006 ZX6R 636 (sold)
    99 S10 ZQ8 (sold)
    95 Merlot M
    05 GSXR 600 (To buy my house)

  3. #3

    Default

    Also if you have the timing bumped set it back to 10 deg.

  4. #4

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    Those after-market cats do not last all that long. I have one that I keep just for my annual smog test so I don't keep having to buy a new one.

  5. #5

    Default

    Wouldn't a bad cat make me fail in other categories though?
    '94 Miata "M Edition" - sold
    '99 Miata w/td05

  6. #6

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    Have you Seafoamed it yet? If not, search on here for tips. That did the trick for me.

  7. #7

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    NAPA sells "Guaranteed to Pass" for $15. I used it once on a friend's beater that had failed, and it passed. Make sure to get the car good and warm prior to the retest.
    Polished Turd Racing

    Mick wrote: "I think Jerrett is the best autocrosser I have ever seen naked."

  8. #8

    Default

    Ok, thanks guys. I'll try those suggestions and try it again
    '94 Miata "M Edition" - sold
    '99 Miata w/td05

  9. #9

    Default

    Quote Originally Posted by Strider View Post
    Wouldn't a bad cat make me fail in other categories though?
    Can't say. I was just suggesting that you might not want to completely discount the cat just because it is 1.5 years old. Maybe try some of the snake oils and then buy a new cat if it still fails. If it still fails with the new cat, then pull it off and sell it for $20 less than you paid. People are always looking for cats around here.

  10. #10

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    Also, read the guarantee on Guarantee to Pass very closely. It is not likely you will get any guarantee if it fails. That is not to say it does not work.

  11. #11
    Team Cheap Bastard
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    Default

    Make sure it's smoking hot before you have it inspected. Go drive the piss out of it, then head to the inspection station.

  12. #12

    Default

    Quote Originally Posted by sammm View Post
    Make sure it's smoking hot before you have it inspected. Go drive the piss out of it, then head to the inspection station.
    This ^^^

    Mine failed the first round because it wasnt warmed up enough. They drove it around the block a few times (after already warmed up) and it passed with flying colors.

  13. #13

    Default

    This could be true because I just drive it half a mile to get inspected
    '94 Miata "M Edition" - sold
    '99 Miata w/td05

  14. #14

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    Yep. The cat has to be above 700 deg F (or something like that) to be fully effective. That's why newer cars have the pre-cats close to head - better emissions during engine warm-up. Go flog it for a bit, then come screeching into the inspection place all Dukes of Hazzard style.
    Polished Turd Racing

    Mick wrote: "I think Jerrett is the best autocrosser I have ever seen naked."

  15. #15

    Default

    Quote Originally Posted by OZMDD View Post
    Go flog it for a bit, then come screeching into the inspection place all Dukes of Hazzard style.
    And hope there is not a long wait.

  16. #16

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    With a stock exhaust, mine barely passed nOX last year. With a full exhaust this year, it should be interesting to see what happens. Sucks to have to take the time to set up the machine though, the car cools down a lot just sitting there while you strap it down and try to find a spot where the shitty inductive RPM detector won't read half or twice the RPM's it's supposed to etc etc. Dyno states are a pain in the ass. Luckily they pay .8 instead of .5 hours.

  17. #17

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    So I decided to go ahead and pull my injectors and clean them up first. Then sea foam it and try and pass
    '94 Miata "M Edition" - sold
    '99 Miata w/td05

  18. #18

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    That's one idea. Can't hurt, but I'd have tried the cheap fix to get my sticker, then worried about injectors at my leisure. Good luck!
    Polished Turd Racing

    Mick wrote: "I think Jerrett is the best autocrosser I have ever seen naked."

  19. #19

    Default

    So I did a compression test Here is what I got cyl 1=130, 2=100, 3=65, 4=140. So I added oil to #3 and it went up to 75 psi. Think it's my valves or valve guide? Can I change them without pulling the motor? Live in an appartment. :-/
    '94 Miata "M Edition" - sold
    '99 Miata w/td05

  20. #20

    Default

    Those are very low numbers. Time for a rebuild. You should be seeing 175-180 all the way across.

    BTW, Make sure when you do the compression test, have it at WOT and crank it about 7 times.
    ...and across the line.

    1996 Mazda Miata - R-Package (Eve-L)
    2012 Mazda CX-9 - Grand Touring (Dory)




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