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Thread: Downpipe Engine Check Lights

  1. #1

    Question Downpipe Engine Check Lights

    Hi All

    Just trying to premeditate a potential problem that I have, I am just getting a new custome made downpipe made and I have been seeing alot of stories on here about how it will pop check engine lights etc etc

    firstly can you just remove the bulbs and it actually be sweet ?

    what are the tips for working round this

    and also I am going to be running a cat free exhaust has anyone else done this ? is it loud ? I expect I ill need to put in some high flow mufflers

    car is still 2 weeks ago and I cant wait to get it back ! should be going like a mofo when I get it back

    cheers

  2. #2
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    cat free exhaust = check engine light, also, illegal

    other than that, will let someone else comment on the rest

  3. #3
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    In the case of the MPS6 & Gen 1 MPS3, you can run single cat, or catless without issues, you just need to put a small elbow where the second o2 sensor sits in order to fool the ECU, the gen 2 MPS3, requires 2 cats, as the program in the factory ECU is a lot less tolerant to changes.

    As far as the legalities, in Australia it is illegal to run a catless exhaust, it is technically illegal to reduce the number of cats and mufflers fitted to the car from factory. Not sure how things are in NZ though.

    If you are still finding issues with a CEL, a dashhawk or scangauge can clear them, as can most workshops with OBD readers.
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  4. #4
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    A single 200 cell cat with the O2 sensor welded in after the cat downstream of the exhaust fixed my CEL's.



    Don't see the point if catless myself. Can't imagine there is any power gains to be had.

  5. #5

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    Cat free also = bad smell and more smoke

  6. #6
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    Quote Originally Posted by Yeldarb View Post
    Don't see the point if catless myself. Can't imagine there is any power gains to be had.
    was speaking to troy when i was up in brisbane, apparently it's a 1-2% gain going form 200CEL to 100 CEL, and about the same again to go catless... so it's ~4-5% difference, but at our (relatively) tiny power outputs, it's probably not really worth it...
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  7. #7

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    I totally agree with the above, I have been looking into several DPs and the thing I don't understand is why companies like CP-e and the like who have at least one cat incorporated into their design just move it upstream towards the turbo and just have the second o2 meter the gases from there??? Or at least have a way to extend the secondary 02 wires and have the o2 just after the cat like it is from factory....

    Wouldn't hit solve the CELs everyone gets with their dump pipes??? It almost seems like a total waste to have a cat downstream of the DP and the two o2 sensors before it, that is just asking for CEL from the get go and yes there are fixes but they're really a hit and miss scenario...

    I would think the ideal setup would be Turbo - Pipe with flange to the turbo and first o2 sensor - High flow cat - Pipe with second o2 - pipe with flange to factory cat back....

    This way you would reduce the number of cats to one which would also help with flow restriction by being a high flow unit and eliminate the CEL issue by having the second o2 metering it.

    I think COBB are the only ones to do something like this???

    ---------- Post added at 01:31 PM ---------- Previous post was at 01:17 PM ----------

    Also just found this: Tuneable o2 Sensor Kit | Custom Performance Engineering
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  8. #8
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    Quote Originally Posted by Malicioso View Post
    I totally agree with the above, I have been looking into several DPs and the thing I don't understand is why companies like CP-e and the like who have at least one cat incorporated into their design just move it upstream towards the turbo and just have the second o2 meter the gases from there??? Or at least have a way to extend the secondary 02 wires and have the o2 just after the cat like it is from factory....

    Wouldn't hit solve the CELs everyone gets with their dump pipes??? It almost seems like a total waste to have a cat downstream of the DP and the two o2 sensors before it, that is just asking for CEL from the get go and yes there are fixes but they're really a hit and miss scenario...

    I would think the ideal setup would be Turbo - Pipe with flange to the turbo and first o2 sensor - High flow cat - Pipe with second o2 - pipe with flange to factory cat back....

    This way you would reduce the number of cats to one which would also help with flow restriction by being a high flow unit and eliminate the CEL issue by having the second o2 metering it.

    I think COBB are the only ones to do something like this???
    That's the exact setup I have thanks to Troys welding skills. No CELS now.
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  9. #9

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    +1 for a 2XS (Troys) DP, have had it on for almost two weeks, not a CEL in sight!

  10. #10

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    don't remove the bulb, CELs come up for a reason

    running catless is highly illegal and you will be shooting flames (cool.. but still) just get a cat and be done with it

  11. #11

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    Quote Originally Posted by lup15 View Post
    don't remove the bulb, CELs come up for a reason

    running catless is highly illegal and you will be shooting flames (cool.. but still) just get a cat and be done with it
    Since johnnymps is in nz, I'll chime in. I don't believe there is any legal issue running catless in NZ. The govt were talking about changing it, but I don't think they have yet. I ran my skyline with no cats and had no issue passing vehicle inspection.

    As for the check engine light issue, these other guys definitely know more about that than I do.
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  12. #12

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    Running catless in a Gen 1 3 MPS or 6 MPS is possible.

    You will require the O2 sensor to be "tricked" by spacing the 2nd O2 from the exhaust system.

    Gen 2 requires a 200 cell cat to work CEL free and can't run catless.


  13. #13

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    Totally different car.. but my friend has a Pulsar SSS and he just de-catted it. It's not alot louder.. you can feel ALOT more power, but it also smells like shit.

    Apparently it's a $20k fine. Lol

  14. #14

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    Okay the mod bug has officially bitten me in the ass, first it was the wheels then the mount, then the intake, but now I want a Downpipe then TIP and later on a tune.

    My question: What's the best way to run a DP in regards to not blowing my turbo seals? I plan on running a catted downpipe most likely the CP-E Downpipe with a 100 flow cat, though if there is a high risk of getting blown turbo seals then I guess I'll just have to hold off on the downpipe until I have enough money for a turbo too just incase it blooowws. Thaaanksssssssssssssssssssssssss

  15. #15

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    The DP will not "blow" the seals.

    If the turbo is on it's way out (as most are) fitting a DP will show the problem sooner because you have less restriction for the burnt oil to escape.

  16. #16

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    Quote Originally Posted by 2XS View Post
    The DP will not "blow" the seals.

    If the turbo is on it's way out (as most are) fitting a DP will show the problem sooner because you have less restriction for the burnt oil to escape.
    ahhhh rightooo, most? wow mazda must have really failed with the k04 huh? ah well I guess the DP will have to hold off till I can save up another 2K

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