the nitty gritty.. Drive by wire...

[wireman134]

In a manual tranny with drive by wire. At approx 2k rpm with pedal to floor does the fuel injection dump fuel or is the fuel mixture optimized for greatest efficiency. My 03 manual vibe without drive by wire only achieved 39. With the manual 07 corolla I can regularly achieve 45-49 in warmer weather.. I am interested in learning why this drive by wire technology seems to be so effective. What does the cpu do to the voltage detected from the pedal? THANKS.

[wireman134]

In short. What does drive by wire do to change fuel map that a cable throttle is unable to accomplish? I am assuming that mid range rpm is all that is effected?

[Paulcet]

Originally Posted by wireman134

In a manual tranny with drive by wire. At approx 2k rpm with pedal to floor does the fuel injection dump fuel or is the fuel mixture optimized for greatest efficiency.

The fuel mixture is optimized for greatest efficiency. This is the case for both cable-actuated and drive-by-wire systems.

My 03 manual vibe without drive by wire only achieved 39. With the manual 07 corolla I can regularly achieve 45-49 in warmer weather.. I am interested in learning why this drive by wire technology seems to be so effective. What does the cpu do to the voltage detected from the pedal? THANKS.

In a drive-by-wire system the CPU controls the throttle plate opening with a small motor mounted on the throttle body. I would suppose that the CPU might not open the throttle plate fully in low rpm situations because it would result in low air velocity, but I don't think it is very important in fuel injection systems.

In both systems the primary factors in the fuel map are intake air mass over time and feedback from the oxygen sensors in the exhaust. I think the differences in your fuel mileage are more due to other factors such as aerodynamics, tire pressure and rolling resistance, weight, intake and exhaust flow.... Did the 03 engine have VVT?

[Bdub215]

Originally Posted by wireman134

In a manual tranny with drive by wire. At approx 2k rpm with pedal to floor does the fuel injection dump fuel or is the fuel mixture optimized for greatest efficiency. My 03 manual vibe without drive by wire only achieved 39. With the manual 07 corolla I can regularly achieve 45-49 in warmer weather.. I am interested in learning why this drive by wire technology seems to be so effective. What does the cpu do to the voltage detected from the pedal? THANKS.

you cant compare the vibe and the corolla. the vibe's got some more heft to it. alot more.

Originally Posted by Paulcet

The fuel mixture is optimized for greatest efficiency. This is the case for both cable-actuated and drive-by-wire systems.

In a drive-by-wire system the CPU controls the throttle plate opening with a small motor mounted on the throttle body. I would suppose that the CPU might not open the throttle plate fully in low rpm situations because it would result in low air velocity, but I don't think it is very important in fuel injection systems.

In both systems the primary factors in the fuel map are intake air mass over time and feedback from the oxygen sensors in the exhaust. I think the differences in your fuel mileage are more due to other factors such as aerodynamics, tire pressure and rolling resistance, weight, intake and exhaust flow.... Did the 03 engine have VVT?

1zz has had VVT-i since 2000.

[wireman134]

There is definitely much less responsiveness in the electronic throttle imo, although you get used to it and without a doubt is much more noticible in manual trans. You feel that disconnect between foot and throttle cable. The 03 was vvt also 1zz I believe. My belief is if we know how the system acheives greater efficiency, we can drive them more efficiently. I for one am willing to put up with sluggish response because of the better economy. I believe that even at full throttle 2k rpm the injectors are only seeing 20% of maximum fuel flow. Almost like it ignores the input from your foot at times. The computer gauges maximum torque for a particular rpm and will not allow additional fuel flow since max torque can be had with only 20% of pedal despession. Just my 2 cents.

[silver04rollas]

My previous 2004 Corolla S (automatic) could achieve 40 mpg without any issues. There is really nothing in drive-by-wire that dictates the fuel economy difference.

You are comparing a Vibe (Matrix) with a Corolla. There most major difference is the curb weight. Both have the same drivetrain, but Matrix and Vibe weigh 300 - 350 pounds more than the equivalent Corolla. More weight for the same engine means more power and fuel reqired to haul the weight. That is where the fuel economy difference is coming from.