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Thread: Doc needs your help :)

  1. #1

    Default Doc needs your help :)

    Hey guys

    Im on a bit of a quest at the moment..

    I dont know if im barking up a tree some of you know about already.. but its a bit of a revelation to me..

    maf diameter seems to be directly related to boost spikes/load..

    Ive done so many logs, and I have proved that a slghtly larger maf will cause the car to overshoot its commanded load tables.. which can lead to a load cut (where im at now on the stock tune)

    I need someone that no longer wants/needs their MPS3 stock air box (ill pay for shipping).. I plan on hacking out the stock maf housing (unable to put back together after my experiment) and adapting a high flow pod filter on it to proove thats its not the restriction removal from an upgraded filter, that gives the kick in the pant that some feel. But more so incorrect load targeting, due to the car seeing less air with the bigger maf, and compensating for its calculated X load by closing the wastegate a little more.. this then causes a boost spike.. and can put the absolute loads above the ECU limits. Even if the car doesnt cut, it will start to close the bloody throttle plate due to it getting confused..

    my theory.. the hacked up stock maf housing will perform exactly the same as the stock air box.. and wont spike like an SRI can.. (even my SRI with an almost 0.0 LTFT will spike. because the cars load tables is calculated with a -3.9% LTFT!

    Anyway sorry if im rambling..

    If anyone doesnt want their stock airbox, or has a spare laying around.. Throw it to Doc, and ill disect it and experiment on it!

    Cheers guys

    Doc
    Last edited by Doc; 02-08-2010 at 02:31 AM. Reason: doc cant type when tired

  2. #2
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    I can't help Doc sorry,I've already modified my airbox and running std filter with a 20kwatw gain, and I'm sure yeldarb has done the same but in Gen 2 and removed the K&N filter he had in and put the std filter in for better results.

  3. #3
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    from what i can gather (in plain english ) you think that an SRI's MAF sensor is reading the air input differently compared to a stock airbox's MAF sensor,making the ECU go so by (effectively) swapping out the SRI's MAF for a stock airbox MAF, it should be ?

    im planning on keeping my stock airbox atm (sorry...) but i wish you all the best with your testing!
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  4. #4
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    Heh, interesting idea, keen to see where it goes.

  5. #5
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    Quote Originally Posted by 240MPS View Post
    I can't help Doc sorry,I've already modified my airbox and running std filter with a 20kwatw gain, and I'm sure yeldarb has done the same but in Gen 2 and removed the K&N filter he had in and put the std filter in for better results.
    What he said.
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  6. #6

    Default

    DING DING DING, WE HAVE A WINNER!

    Changing the housing diameter slightly is what gives the power increase.

    Changing it too much is what causes the "overload"

    Power is made because "we" lean the car out slightly, which inturn, increases power.

    I've seen it somewhere in the USA threads, where someone "hacked" the stock airbox to adapt a pod and made NO extra power.

    The trick is to "know" what to do, in this situation.
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  7. #7

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    thanks guys

    yes a larger maf will add power.. but not because it is leaning it out (it may c
    Last edited by Doc; 03-08-2010 at 03:19 AM.

  8. #8
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    This is fairly important information, in terms of this online community I mean.

    Till reading this thread, I had been under the impression that after market intakes had pretty simply reduced restrictions of the airflow into the turbo/motor. The implication being that the stock airbox/filter could not flow enough air and therefore "starved" the engine of the air it needs to make power.

    How many times have I read "upgrade the intake and exhasust, help that engine breathe"

    But to clarify, what you guys are saying is: An after market intake (whether SRI or CAI) WITH THE SAME MAF DIAMETER AS THE STOCK AIRBOX will have absolutely no impact on engine performance?

    Maybe its just me, with my almost complete lack of mechanical experience, but thats a bit of a revelation.

  9. #9

    Default

    Yeah

    in a nut shell that's right. I'm not overly concerned with restriction per say. I'm really interested in the load mapping and the differences..

    I was hoping to get my hands on a stocker.. So I can proove with logs that there is no difference, if you don't change the maf housing.

    In saying that, as soon as you get a rune, they recallibrate your maf signal anyway... Hhhmmm


    Doc

  10. #10
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    Doc i know your housing was modified to almost exactly OEM hence no CEL and very good LTFT, at idle and moderate rpm, Previous threads re SRI problems pointed to intake sizes from some suppliers slightly oversized. From memory mine was ID approx 0.08 to 1.00mm larger,threw CEL (P2096) run lean code ,and since modified straightener,no further occurences,ECU has learned and now my LTFT are running positive ,which justifies adding fuel as Maf is signaling to ECU increased air volume ,outside std parameters /mapping.


    AllStar dyno day showed my lambda as very similar to Stock cars.,give or take a small percentage.


    Current LTFT as posted previously ,Dashawk points to RICH,which should be rectified once tuned , therefore power will be benefited from SRI with a slightly larger Diameter and bring my Trims back to closer to Zero.

    Point is that an SRI will benefit ,BUT u need to Tune in order to gain any increase HP. Adding SRI and no Tune will only increase fuel usage and throw excess out the Exhaust as your Mapping is STD.

  11. #11

    Default

    long shot bump for an mps 3 standard airbox in the name of science

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