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Thread: To tune, or not to tune, that is the question

  1. #1
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    To tune, or not to tune, that is the question

    Got a ? about running headers with the M54b25 intake manifold swap, on my 99 2.3 roady, is it necessarily mandatory to do a tune, not really familiar with getting a tune, any advice would be appreciated.

  2. #2
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    Its not mandatory to get a tune. When the M54B25 intake was fitted to my E46 323i (same mod as your car), the improvements were immediate and no tune has been done.
    1999 2.8L Z3 Roadster,
    2000 3.0L Z3 Roadster,

    There is only one thing more pleasurable than working on a Z3, that's driving it top down on a fine day.

  3. #3
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    If you are putting headers on your M52, you will be replacing exhaust manifolds that had integrated catalytic converters. Unless your new headers have integrated catalytic converters, or you have a shop put in converters downstream, you will be running without a cat. That means your will be removing your downstream O2 sensors as well.

    The car will run fine without them, but you will get a persistent check engine light. To some people, that's ok, but it also means that light can no longer tell you when any other issue is causing problems. You'd have to run the trouble codes periodically to make sure everything else is running normal.

    A tune would have the car performing better with your modification, but also could program the DME to ignore the post-cat O2 sensors. That way you'd only get notified for any other issues on your car.

    If for no other reason, I'd get the tune to have a working CEL.

  4. #4
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    Quote Originally Posted by Schreier View Post
    If you are putting headers on your M52, you will be replacing exhaust manifolds that had integrated catalytic converters. Unless your new headers have integrated catalytic converters, or you have a shop put in converters downstream, you will be running without a cat. That means your will be removing your downstream O2 sensors as well.

    The car will run fine without them, but you will get a persistent check engine light. To some people, that's ok, but it also means that light can no longer tell you when any other issue is causing problems. You'd have to run the trouble codes periodically to make sure everything else is running normal.

    A tune would have the car performing better with your modification, but also could program the DME to ignore the post-cat O2 sensors. That way you'd only get notified for any other issues on your car.

    If for no other reason, I'd get the tune to have a working CEL.
    Yeah man, thanks for the skinny, im guessing those O2 sensor simulators, that the Bimmerworld site has for $109.99 each would do the trick?

  5. #5
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    Quote Originally Posted by streetmaster56 View Post
    Yeah man, thanks for the skinny, im guessing those O2 sensor simulators, that the Bimmerworld site has for $109.99 each would do the trick?
    I'm not familiar with O2 simulators, so I can't really speak about them. Hopefully someone could chime in on that in particular.

    But my opinion on them is a tune would cost about the same amount of money, and the O2 sensor simulators aren't going to give you better performance than the tune would. I'd go straight for a tune that ignores the O2 sensors and nets more gains from the headers.

    There could be other circumstances that make the simulators more practical, but I can only think of a few cases, most involving emissions testing of some kind. Dunno.

  6. #6
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    Quote Originally Posted by Schreier View Post
    I'm not familiar with O2 simulators, so I can't really speak about them. Hopefully someone could chime in on that in particular.

    But my opinion on them is a tune would cost about the same amount of money, and the O2 sensor simulators aren't going to give you better performance than the tune would. I'd go straight for a tune that ignores the O2 sensors and nets more gains from the headers.

    There could be other circumstances that make the simulators more practical, but I can only think of a few cases, most involving emissions testing of some kind. Dunno.
    So a tune would involve the installation of a chip, or a total reprogram of the DME, this is kind of my first journey into the dark hole of programming lol.

  7. #7
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    Quote Originally Posted by streetmaster56 View Post
    Yeah man, thanks for the skinny, im guessing those O2 sensor simulators, that the Bimmerworld site has for $109.99 each would do the trick?
    Waste of money, you can tune them out

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  8. #8
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    Quote Originally Posted by BimmerBreaker View Post
    Waste of money, you can tune them out
    Thanks for the heads up, a tune it will be.

  9. #9
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    Do it

  10. #10
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    alright - i'm sorry if i'm jerking the thread to the left, but here goes:

    i'm planning to resurrect my 2.5L z3 that has been parked for years. on my list of things to do is add a supercharger. i mean, why not? so i've wondered the same thing - to "tune" it or not. but i am a serious DIY kinda guy, so i don't want to pay someone else to do it.

    i'm not afraid of electronics or software (i'm an EE). if i wanted to buy an OBD-II interface and supporting SW so i could do this myself, what would the forums recommend? are there resources for me to read / reference? is there a BMW toolset that you'd all recommend?

    why would i go to some teenager to do it? am i being too old and curmudgeony?

    i suppose the ultimate reason to pay some kid to do it would be that the hardware / software cost is so prohibitive it doesn't make sense to do it for a one-off application...

    what's the forum say?
    Cheers,
    Phil

  11. #11
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    Quote Originally Posted by pwhitt View Post
    alright - i'm sorry if i'm jerking the thread to the left, but here goes:

    i'm planning to resurrect my 2.5L z3 that has been parked for years. on my list of things to do is add a supercharger. i mean, why not? so i've wondered the same thing - to "tune" it or not. but i am a serious DIY kinda guy, so i don't want to pay someone else to do it.

    i'm not afraid of electronics or software (i'm an EE). if i wanted to buy an OBD-II interface and supporting SW so i could do this myself, what would the forums recommend? are there resources for me to read / reference? is there a BMW toolset that you'd all recommend?

    why would i go to some teenager to do it? am i being too old and curmudgeony?

    i suppose the ultimate reason to pay some kid to do it would be that the hardware / software cost is so prohibitive it doesn't make sense to do it for a one-off application...

    what's the forum say?
    Not real sure what a guys age would have to do with anything, if he/she knows more about it than I do, so be it, given the fact that computers and tunes aren't one of my strong points, I appreciate any advice I get.

  12. #12
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    always tune.


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