What is the difference between SEFI and batch fire or bank to bank? Which one is better?
[back] MPFI systems operate between 30 – 45 psi with one of two different firing strategies. These can be either bank to bank also known as batch fire, or sequential (SEFI). Bank to bank systems fire all or some of the injectors on an engine bank at the same time. A SEFI system fires each injector individually just prior to the fuel being needed for the firing event SEFI systems require extra sensors to determine proper fuel delivery to the correct cylinder at the right time. SEFI systems are used to comply with OBDII requirements and potentially deliver lower emissions. This writer has calibrated both bank to bank and SEFI systems, and found very little emissions advantage with the SEFI system. With the standards being what they are today though, even a .01 gm/mi advantage can be tremendous. (See page for emission requirement discussion). For most engines that are not being used for high revving race applications batch fire or bank to bank works just fine. SEFI systems as previously d
