And the difference is? As I see it,

MFI = multi-port fuel injection (a separate fuel injector for each cylinder);

EFI = electronic fuel injection (injectors controlled by microprocessor, electrically rather than mechanically activated).

Subaru fuel systems (at least going back to your 99) are both MFI and EFI.

I presume the replacement will be from a Subaru of the same "year/engine size etc".

 

right, i understand the difference between injector types. but does that have any bearing on what MAF sensor i get? the used part dealer has one that is spec'd from a '97 with MFI, and one from a '99 with EFI. From what i understand, either will physically fit, but does it make any difference otherwise?

and is there a way to visibly tell if the engine is mfi or efi?

thanks

 

I don't know which engines they are used on, but they do use different types of maf sensors on different engines. Some are the single wire sampling type and some are the screen. Best way is to look up part numbers for them or compare the old ones.

 

and is there a way to visibly tell if the engine is mfi or efi?

It's not necessary. As I mentioned, Subaru engines going back a long way are both MFI and EFI. There are as many injectors as cylinders (that's the "Multi-port fuel injection") and the injectors are electronically operated (that's the Electronic fuel injection).

Don't worry about others' confusing terminology. Just make sure it's the same MAF type (as Seabass noted) or at least comes from the same year (99), model, and engine (e.g., 2.5, non-turbo, with automatic transmission, if that's what you have). Part numbers can be checked on sites such as opposedforces.com.

 

cool, thanks!

on a related note - should the broken MAF sensor cause a CEL? my CEL has not gone on, even though i expected it to...i'm also not noticing any difference in performance at all. do i really need to rush out and get the MAF sensor replaced? i haven't yet checked for codes, but i'm assuming i should at least get a code thrown, right?

 

What did you do to it that makes you believe it is broken?

 

well...i definitely broke it. i had incorrect instructions on how to remove it, and instead of just disconnecting it from the intake, i tried to remove the electrical clip socket, and thus snapped the leads that connect the socket to the sensor. it's possible that even though the leads are broken they're still touching enough to work, but i don't know how likely that is...

 

so still to code for the MAF sensor, and I've not had any rough starts or idles or anything - maybe the leads really are touching well enough even though they're broken...

but, since i know that it is broken, and assuming the sensor is NOT working correctly, how critical is it to replace this part? aside from poor gas milage, will it affect other components of the car?