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  1. #51
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    1 out of 1 members liked this post. Yes Reputation No
    Great news indeed, but I'm not ready to give up on my easy bake over just yet....

  2. #52
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    Click here to enlarge Originally Posted by vasillalov Click here to enlarge
    Reading from the Cobb documentation, I found an interesting piece of information. It appears that the N54 engine speed is regulated via the injectors and the ignition system. The throttle body is used predominantly for boost control. All this makes sense, but what I want to know if the following is true:

    Say you are cruising leisurely on 4th gear. The engine is operating in vacuum at this point. You then decide to speed up rapidly and you put your foot down. The ECU sees this as a request for more load, determines that it needs more boost to meet the new requested load target and then actuates the waste gates which up to this point were almost completely open because the engine was in vacuum.

    Your foot is still down on the pedal waiting for response. Wastegates shut, turbos spool, boost builds up before the throttle plate. The ECU sees the increase of the boost and then opens the throttle plate, releasing all the accumulated boost into the manifold and finally the engine delivers requested output.

    If all this is true, in order to fiddle with the throttle response (which is what I want to do at this point), I need to trace the maps in ATR in the following path:

    Accelerator Pedal Position -> Requested Load Target -> Waste Gate Duty % -> Throttle Plate Position

    Does this sound right?
    As soon as you start pressing on the accelerator, the DME is going to open the throttle body to let as much air as possible into the engine - even with 0 boost. I believe what you should be looking at is your timing advance, which really needs to be dialed in on a dyno so that you can find MBT, and tune around it. Adding timing will give the car an "eager" feeling, vs laggy feeling. Cobb ots maps are very conservative on how much timing they run.

  3. #53
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    this sounds good, should i be ditching the JB4 for Cobb alone, or keep it and add Cobb on as well?

  4. #54
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    As soon as you start pressing on the accelerator, the DME is going to open the throttle body to let as much air as possible into the engine - even with 0 boost. I believe what you should be looking at is your timing advance, which really needs to be dialed in on a dyno so that you can find MBT, and tune around it. Adding timing will give the car an "eager" feeling, vs laggy feeling. Cobb ots maps are very conservative on how much timing they run.
    You do understand MBT changes as boost pressure changes right? Pick the appropriate boost curve and tune everything else around that. If you're running Cobb alone fueling and vanos should be dialed in appropriately if you are using an OTS map as your base. Always a fine line with timing and boost it seems. Can always add more fuel if it's not slowing you down too much.

  5. #55
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    Click here to enlarge Originally Posted by boostingwild Click here to enlarge
    this sounds good, should i be ditching the JB4 for Cobb alone, or keep it and add Cobb on as well?
    Ideally stacking isn't a terrible option since it provides auxiliary features that Cobb alone does not offer.

  6. #56
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    Is it realistic to think a shop with pro tune ability and some n54 experience could properly tune a RB powered car? I'm thinking of getting rb's this winter and would most likely go to a place like efi for tuning. When cobb says there are variations from car to car, that makes me nervous. I am not experienced enough to play with ATR yet. The last thing I want to do is spend money on a nice RB set up for the car to run horribly and have boost oscillations.
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  7. #57
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    Click here to enlarge Originally Posted by themyst Click here to enlarge
    You do understand MBT changes as boost pressure changes right? Pick the appropriate boost curve and tune everything else around that. If you're running Cobb alone fueling and vanos should be dialed in appropriately if you are using an OTS map as your base. Always a fine line with timing and boost it seems. Can always add more fuel if it's not slowing you down too much.
    Yep, not sure i understand what you're getting at?

  8. #58
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    Just read the Cobb user tuning guide. Cobb FTMFW. I can't wait to see some awesome results.

  9. #59
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    Click here to enlarge Originally Posted by Q4P Click here to enlarge
    Waiting to see how long for the first e90 post "tooner" to blow an engine...
    Could be an intersting question, who wants a piece of that action? What's the projected over/under before somebody blows up?

    Seeing how there have been more than one "why is my car misfiring/running poorly, I'm only running Stage 2+ without appropriate mods because my mechanic buddy told me it's okay" threads...I'll pick 45 days before the first one goes. Anyone else?

  10. #60
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Yep, not sure i understand what you're getting at?
    You stated you would tune timing first.

  11. #61
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    Click here to enlarge Originally Posted by Skyhart Click here to enlarge
    Could be an intersting question, who wants a piece of that action? What's the projected over/under before somebody blows up?

    Seeing how there have been more than one "why is my car misfiring/running poorly, I'm only running Stage 2+ without appropriate mods because my mechanic buddy told me it's okay" threads...I'll pick 45 days before the first one goes. Anyone else?
    I say not for a long time.

  12. #62
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    Wow,nice Cobb. I wasn't sure if this was ever going to happen. Looks like I may be stacking a G5 and Cobb this winter. Hoping to have a set of RBs before the strip opens back up next spring.
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  13. #63
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    Click here to enlarge Originally Posted by Skyhart Click here to enlarge
    Could be an intersting question, who wants a piece of that action? What's the projected over/under before somebody blows up?

    Seeing how there have been more than one "why is my car misfiring/running poorly, I'm only running Stage 2+ without appropriate mods because my mechanic buddy told me it's okay" threads...I'll pick 45 days before the first one goes. Anyone else?
    I just hope they know enough to know not to mess with something they know nothing about. I think the average e90poster may be too intimidated to just get in there and start tweaking anything they can click on.
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  14. #64
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    Click here to enlarge Originally Posted by rader1 Click here to enlarge
    I just hope they know enough to know not to mess with something they know nothing about. I think the average e90poster may be too intimidated to just get in there and start tweaking anything they can click on.
    I wouldn't count on that. I am sure they will read what other people have done, think they can get away with the same thing and then have major issues.

  15. #65
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    Click here to enlarge Originally Posted by vasillalov Click here to enlarge
    Reading from the Cobb documentation, I found an interesting piece of information. It appears that the N54 engine speed is regulated via the injectors and the ignition system.
    Is this something we didn't know earlier? Does make complete sense.
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  16. #66
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    Click here to enlarge Originally Posted by ATP Click here to enlarge
    I wouldn't count on that. I am sure they will read what other people have done, think they can get away with the same thing and then have major issues.
    Why would novices even be messing with it? This should be for experienced users who want more control and adjust-ability. If anyone screws something up with this they have nobody to blame but themselves. People have been clamoring for it and now they have it. Those who don't know what they are doing should be on the sidelines or using Cobb's own maps.
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Why would novices even be messing with it? This should be for experienced users who want more control and adjust-ability. If anyone screws something up with this they have nobody to blame but themselves. People have been clamoring for it and now they have it. Those who don't know what they are doing should be on the sidelines or using Cobb's own maps.

    It would seem reasonable. But then again, why would somebody run the wrong map for the mods they have and actually post a question as to why they're having issues. ATR is great, but you can't police "stupid" and somebody is bound to test that. I would bet the average user won't have issues.

  18. #68
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Is this something we didn't know earlier? Does make complete sense.

    Well, to me it was interesting piece of information. I think only DI motors are this way. Regular port injection motor speed is increased by opening the throttle body.
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  19. #69
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    Click here to enlarge Originally Posted by Skyhart Click here to enlarge
    It would seem reasonable. But then again, why would somebody run the wrong map for the mods they have and actually post a question as to why they're having issues. ATR is great, but you can't police "stupid" and somebody is bound to test that. I would bet the average user won't have issues.
    If someone is stupid enough to mess with their motor without knowing what they are doing they earn everything that happens to them.
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  20. #70
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    If someone is stupid enough to mess with their motor without knowing what they are doing they earn everything that happens to them.
    That's said in a pretty harsh tone as many have learned by exactly that, trying things, including most if not all of our well respected tuners. Letting someone more knowledgable on the subject that has already seen many things work or not work is always a better idea of course.
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  21. #71
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    Click here to enlarge Originally Posted by bobS Click here to enlarge
    Is it realistic to think a shop with pro tune ability and some n54 experience could properly tune a RB powered car? I'm thinking of getting rb's this winter and would most likely go to a place like efi for tuning. When cobb says there are variations from car to car, that makes me nervous. I am not experienced enough to play with ATR yet. The last thing I want to do is spend money on a nice RB set up for the car to run horribly and have boost oscillations.
    then you should forget and JB4 cobb if you are thinking to run well rb turbos


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  22. #72
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    That's said in a pretty harsh tone as many have learned by exactly that, trying things, including most if not all of our well respected tuners. Letting someone more knowledgable on the subject that has already seen many things work or not work is always a better idea of course.
    (I tried to positively rep this one, not enough rep myself)
    Exactly, as long as someone has enough common sense to know where to start and when to stop, the only way to learn this kinda thing through experience and experimentation.
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  23. #73
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    Click here to enlarge Originally Posted by bobS Click here to enlarge
    Is it realistic to think a shop with pro tune ability and some n54 experience could properly tune a RB powered car? I'm thinking of getting rb's this winter and would most likely go to a place like efi for tuning. When cobb says there are variations from car to car, that makes me nervous. I am not experienced enough to play with ATR yet. The last thing I want to do is spend money on a nice RB set up for the car to run horribly and have boost oscillations.
    you have 2 options I can think of, well, 3

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  24. #74
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    Well this is good news. I guess it's time for me to get a Cobb again.

  25. #75
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    That's said in a pretty harsh tone as many have learned by exactly that, trying things, including most if not all of our well respected tuners. Letting someone more knowledgable on the subject that has already seen many things work or not work is always a better idea of course.
    It isn't harsh at all. If you want to learn with the trial and error method then deal with the consequences.
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