Difference between MPFI & SEFI

Hi All,

As we all know MPFI (Multi Point Fuel Injection) is common fuel system used in petrol cars, it uses 'batch firing' technology and fires all the injectors for one bank of the engine at once.

SEFI (Sequential Electronic Fuel Injection) also know as SFI. It fires each injector separately and gives slightly better fuel mileage and less emission at lower RPMs compare to MPFI.

Currently I see Ford & Chevrolet vehicles comes SEFI whereas Maruti & Hyundai vehicles comes with MPFI

So which technology is good?

‘Mpfi’ stands for 'multi point (electronic) fuel injection'.

This system injects fuel into individual cylinders, based on commands from the ‘on board engine management system computer’ – popularly known as the Engine Control Unit/ECU

Mpfi Systems can either be :

a) ‘Sequential’ i.e direct injection into individual cylinders against their suction strokes, or

b) ‘Simultaneous’ i.e together for all the four or whatever the number of cylinders, or

c) ‘Group’ i.e into Cylinder-Pairs.

Of these variants of Mpfi, 'Sequential' is the best from the above considerations of power balance/output.

'SEFI' stands for 'Sequential Electronic Fuel Injection', which technically is the best of the above variants of Mpfi.

Source: www[dot]indiacar[dot]com

So does it means SEFI is better than MPFI?

What are the advantages and disadvantages considering SEFI & MPFI engines?

I did not interpret this info as 'SEFI is better than MPFI'. SEFI is a method of implementing MPFI in an engine.
I think Its a marketing gimmick used in an attempt to outshine the features of a competetior.

Both deal with Fueling.

Direct(sequential) is much more advanced and accurate-gives better efficiency also. The downside is cost.

Ok.

I don't think it's a marketing tact, but there are technical differences too in both type of engines.

I see that Spark is having engine with SFI fuel system. I have seen in threads that due to lower gear ratios people need not to change them in traffic. I mean running on 30 at 4th gear and even can pull easily without downgrading.

I agree that both deal with fuelling. Broadly speaking, i would call SEFI as a 'subset' of MPFI rather than comparing it as MPFI vs. SEFI.
Spark deploys sequential injection, but the fuel intake type would still be MPFI in broad terms, right ?

If I may jump in...yes, agree with Bhejdo that sequential injection IS a sub-set of MPFI - in fact it is a descendent of MPFI in that it has all the features that MPFI has (like every cylinder has its own injector(s).

In addition to the above, IMO sequential injection is not a new thing: As per what I read on wikipedia, sequential injection means that the injector is fired only when the corresponding intake valve opens, instead of firing injectors in pairs or all at once.

Note: Two consecutive posts merged.

Thanks Rohit,

So with this technology of SFI, does it affects (Increases) on power & mileage?

I think SFI will help to give seamless power