Since I own a 2007 Civic Si with the new drive by wire system (no throttle cable), I found it interesting when I come across info for it. Enjoy!
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A DBW (Drive By Wire) system provides high-precision control over the throttle valve while the valve timing is being changed over, ensuring smooth driving performance that leaves the driver unaware of any torque fluctuations.
Under low-load conditions on conventional engine, the throttle valve is normally partly closed to control the intake volume of the fuel-air mixture. During this time, pumping losses are incurred due to intake resistance, and this is one factor that leads to reduced engine efficiency. With the i-VTEC engine, however, intake valve closure timing is delayed to control the intake volume of the air-fuel mixture, allowing the throttle valve to remain wide open even under low-load conditions for a major reduction in pumping losses of up to 16%. Combined with comprehensive friction-reducing measures, this results in a significant increase in fuel efficiency for the engine itself.
When cruising, the ECU keeps the throttle wide open in order to decrease pumping losses. This technology is one of the reasons why the engine gets such high MPG.
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Someone also sent me this:
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Drive by wire only causes lag when the writers of the software allow it to. It isn't an inherent issue with DBW.
Engineers like DBW because it allows the computer to control throttle angle for many different situations, one example was already mentioned.
DBW also allows engineers to get rid of the idle air bypass valve because the computer will keep the throttle cracked open slightly when necessary. That saves money. In the auto industry $$ rules.
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As far as fuel economy, my 07 Si gets about 33mpg in mixed driving (since I'm in traffic a lot). 390-400miles per tank and 12 gallon fill up.
If I get more info, I'll post it here.
11-09-2006, 07:23 PM
Drive By Wire (DBW) Honda System
Linear Mode
