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Thread: MAF readings discrepancies

  1. #21
    NostraJackAss Jack@European_Parts's Avatar
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    No, there is no such forum rule. That's just Jack being Jack.
    Happy Easter Uwe...........

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  3. #22
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    Quote Originally Posted by Jack@European_Parts View Post
    So you have drank the Kool-aid......?

    The difference between "True Motorsports" and just delete or defeat devices is where you have to consider is the SMOG device really hindering an alleged performance characteristic or is it that someone can't tune or is lazy and they direct you to delete it & because they set a control table to ZERO?

    No real rocket science to setting stuff to zero huh, is that to be respected?


    I guess my question to you and any of the tuners is, if the engine is running allegedly more efficient after one of these tunes and with harmonious combustion, why would you have to delete the CAT or readiness monitors and if you didn't remove the physical CAT, why would the CAT exhibit shortly after such a tune & at a 99% failure RATE on an actual factory CAT & being completely damaged, restricted or plugged?
    By serious mapper I meant someone with some serious engineering background and the right tools to do the job, amongst others a dyno, a set of sensors to complement those of the car if need be, and a proper analysis and programming environment. In my view these are the prerequisite to map a car correctly.
    Now I'm certainly no expert but I see mapping (as opposed to any physical modifications which can be done in parallel) as a 3 steps approach. The first level is to optimise the engine operation for MY car taking into account its current state (including parts ageing!) and as you said optimize combustion under different loads.
    Second level is about pushing the limits like pushing turbo pressure, tightening advance timings, increase fuel pumps reactivity, etc.
    If property done the first 2 steps are a win on all fronts : performance, fuel consumption and emissions are optimized.
    Now the third level is true Motorsports where environmental considerations are no concern. It's all about the performance by any means leading for instance to much richer mixtures, but in my view this is where the game should end. 3rd level is to be kept only for circuits and certainly not for the Jones willing to play with a performance car.
    On a side note, I tend to believe some physical modifications are really worth it for performance gains whereas others are very questionable, like removing sai and evap systems. For cats, having a higher exhaust flow makes a significant improvement and provided I'm well below the emissions limits (thanks to a bespoke mapping ) I'm not ashamed with my choice for sport cats.

    So here's my take on the subject, and I suppose most of it has already been said much better in the aforementioned thread that I still need to read!
    Last edited by Classik; 04-22-2019 at 01:42 AM.

  4. #23
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    Quote Originally Posted by Uwe View Post
    No, there is no such forum rule. That's just Jack being Jack.

    Now remaps do make trouble-shooting more difficult. I've seen it myself where a car with stock software ran pretty well, but "tuned", it was horrible, and the source of this was eventually traced to a small vacuum leak. So a "mapped" ECU can behave quite a bit differently. In addition, some tuners seem to think it's necessary or desirable to disable certain tests for faults...
    -Uwe-
    Ha, this I can understand as a remap tend to push the limits, but you would also agree it's a good thing it helped to identify an air leak, and I'm pretty sure the leak was causing some performance degradation with the oem map without the driver knowing it! Playing the devil's advocate of course, but having said that what is the real conclusion of the above story?


    Quote Originally Posted by Uwe View Post
    No, there is no such forum rule. That's just Jack being Jack.

    Those calculations -- turning analog sensor readings into something resembling real-world values like g/s -- are done by the ECU, not VCDS. Now the digital value that the ECU sends to VCDS may still not be g/s, but that conversion will be some well-understood formula that isn't likely to be wrong, especially on 2003 car.

    -Uwe-
    Thanks for the confirmation, so there's no way I can have access to more details about those MAFs readings, particularly what really goes out of the MAF (voltages, etc.), except of course by tapping the wires.

    So back to the original issue, what I need to do is check again those wires with a multimeter and if not the culprit try to find a couple of MAF wiring extension to connect MAF 1 to connector 2 (and vice versa), so that I'll know whether it comes from the ecu or not.
    Last edited by Classik; 04-21-2019 at 11:01 AM.

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