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Originally Posted by Optimus Prime
No, DBW throttle isn't that much of an issue. Most tuners will allow the stock ECU to control the DBW cable, and interface it with another engine management, although with cars like the Subaru STi, that has DBW, they have chip systems, like Hondata, that will adjust all the necessary settings on the stock ecu (products like EcuTek and Cobb AccessPort).
MAF is a big problem because (well this is more pronounced in a turbo car) if the air turbulence is greater than stock, you will get incorrect readings. This is why on an STi, only two aftermarket intakes work. The AEM and others tend to create turbulence around the MAF and it gets incorrect readings. The big problem will be when turboing the car. The distance between the MAF and the throttle body will matter, then if you need bigger injectors, you will need to scale them in the ECU, or get a larger diameter MAF housing to adjust for the bigger injectors. Also with turbos, you now can't have a Blow Off Valve that vents to the atmosphere as you will cause the car to run rich by blowing out air that has already been metered. Of course then you can try and design a blow through MAF setup, but that takes some time and a good engine management setup.
The thing in the past that made tuning a Honda so fun was the lack of the MAF, now things will be difficult, unless Hondata comes out with something real slick.
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Ah, thanks. It was kinda of confusing. It seems less so of a problem for S/C the car than it is for turboing. But most of the turbo/S/C kits I've seen for different cars with MAF sensors, like VR6's, come with larger MAF housings. I've seen the design of a MAF plug. It's interesting how they divert airflow over the sensor. But it makes sense that a BOV (that releases to the atmosphere not back into the system) would cause the MAF to run rich.
So with the DBW on the STi's and BMW's does the chip actually increase throttle sensitivity? That seems to be a problem with the Si, is it's lack of sensitivity during spirited driving. I know the lag was a tad annoying. I've heard people getting annoyed about the artifical way the revs hang but I thought it was a good thing. It allowed me to enter a corner at a high rev and maintain VTEC all the way through so I could exit faster.