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01-04-2009, 12:07 AM | #23 |
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BimmerRob08,
It's like J08M3 said. MAP sensor (Manifold Absolute Pressure) MAF sensor (Mass AirFlow) The S65 V8 M3 uses a MAP sensor. If you wanna learn more on these sensors readup on them on Wikipedia. http://en.wikipedia.org/wiki/MAP_sensor http://en.wikipedia.org/wiki/Mass_flow_sensor Map sensors don't see changes in engine volumetric efficiency as well as MAF. Since BMW tuned the DME according to it's factory tested % of engine volumetric efficiency, with required values to make there performance requirements. Now adding a few extra % of volumetric efficiency on a engine from a exhaust and air filter. The DME doesn't see them as well with a MAP sensor and cannot adjust the fuel for optimum performance. But the engine has safeties built in so you don't damage the motor from leaning out. By using the integrated 8 knock sensors and 4 O2 sensors. Now this is what i know, but i don't know all the DME functions and tune. As i'm no tuner. Maybe tuners on here will clear some of this up. |
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01-04-2009, 03:42 PM | #24 |
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Sweet!! Clear as mud! Thanks for clearing that up a bit. So basically the programed ECU OEM settings, is tuned to the air intake and exhaust. By changing these two variables, inlet & exhaust, the ECU must recalculate the changed perameters but both of the modifications people do are still well within the limits of the ECU I take it?
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01-05-2009, 12:27 AM | #25 |
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Good info... does anyone know if the ECU will then adjust automatically after driving a while with a new filter and / or exhaust to the new volume efficiency or is a reflash really the only way to take advantage of these bolt-on mods?
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01-05-2009, 02:36 AM | #26 |
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Another thought
It has been our experience that if you design a rear silencer (or silencers) that use too big a section, the loss of back pressure results in a substantial loss of low-end and mid-range torque, with no benefit in the higher RPM range. In fact, the impression you are getting when you feel the car pull harder up top, may very well be that you have lost quite a bit below and your car just feels quicker when, in fact, it is no quicker than stock. A before and after dyno run should be able to confirm this for you.
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01-05-2009, 10:29 AM | #27 | |
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Drives: BMW (E92) M3 & 2004 JCW MCS
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Quote:
Waiting to fit my X-pipes by AA on my ride tomorrow so I should expect to free up a lil more in my baby. let you know soon
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01-05-2009, 11:33 AM | #28 | |
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Quote:
Changing only the rear mufflers doesn't really do much does it? (I mean it's 'safe') |
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01-05-2009, 08:24 PM | #29 |
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Just because the S65 uses a MAP sensor does not mean that it will run poorly/worse than stock if modified within reason. With things like intake and exhaust, the ECU will see a deviation in the LTFT and adjust fueling accordingly.
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01-05-2009, 09:59 PM | #30 |
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I would agree that a replacement filter would be close to zero on an EU car. The US cars are stuck with the charcoal layer built in their filters so there is a small gain. AA's dyno for their paper replacement, which looks a lot like a stock EU filter, was showing 5-7 hp differences over the US stock version.
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01-06-2009, 05:17 PM | #33 |
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So, does anyone else feel a power/torque loss from about 2k rpm-3k rpm? I actually find it pretty noticeable in acceleration going up a slight incline in 2nd or 3rd gear.
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01-06-2009, 06:03 PM | #35 |
yodog
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2009 E92 M3 | Alpine White | Black Extended | Advan RS | Turner Test Pipes | Dinan Axle-Back | OETuning | Eibach Springs | UUC SSK | VRS Front Lip | VRS Type I Diffuser | Matte Black | RPi Scoops | MS Filter | Yokohama AD08 | F1 Pinnacle Special Thanks: Gintani | OETuning | eAs |
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