Port delivered Electronic Fuel Injection systems offer the advantage of not having to move fuel through the intake manifold. This allows for improved performance and emissions through optimum design of the intake air chamber and manifolds.
A large intake air chamber is provided to eliminate pulsation, thereby improving air distribution to each manifold runner. Long, narrow manifold runners are branched off to each intake port to improve air velocity at the intake valve. This design offers the following benefits:
• Fuel puddling is eliminated, providing for leaner cold engine and power air/fuel ratios. This equates to reductions in emissions and improved fuel economy.
• Volumetric efficiency of the engine is improved, thereby improving engine torque and horsepower.
Depending upon application, the intake air chamber and manifolds may be integrated or separate. Some Toyota engines utilize an ECU controlled variable induction system which optimizes manifold design for low and high speed engine operation. For more information on these systems, refer to "Other TCCS Related Systems."
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