I'm trying to understand my engine.
Can someone please explain whether CPI and CMFI are two different things or not? The way I understand it, you would either have a central port injection system or a multi-point injection system--do I have that right, or am I missing something?? The reason I ask is that I have been told that my engine is CPI and also that it is CMFI. So, which is it, or is it both?
I have the 95 Blazer vin W. Thanks for any clarification.

 

It's been discussed before.

CPI (like '92-95' but unsure of first year used) == Central Port Injection --> The CPI system uses 1 electronic, batch fired fuel injector feeding 6 individual, pressure actuated poppet nozzles in the intake runner.

SCFI ('96-mid'02) == Sequential Central Fuel Injection --> The SCFI system uses 6 electronic, sequentially fired injectors located in a central injection body. Each electronic injector feeds 1 individual, pressure actuated poppet nozzles in the intake runner.

MFI (late'02-current) == Multiport Fuel Injection --> The MFI system is backwards compatible with the SCFI engines. Like the SCFI system, the MFI system has 6 sequentially fired, electronic fuel injectors, but these injectors are moved out to the intake runner, replacing the problematic poppet nozzles.

Hope that helps. So you're '95 is a CPI motor.

 

Sweet, this helps me understand my engine now too, I was just decoding the VIN to find out what I had, from the other post you had. I thought I had MPI but I guess I have SCFI since I have a 98 with a W in the VIN position for engines. I assume that the SCFI is the one that has the fuel spider that seems to go bad every once in a while on some vehicles?

 

Yeah, that VIN decode I posted isn't all that accurate... There's a lot missing.

 

That does help, and I don't mean to be a pest, but...my BIL insists I have central multi-point injection (CMFI)...could that be correct?? Also, on this webpage it says 95 had CMFI: http://www.answers.com/topic/chevrolet-s-10-blazer (scroll down about 2/3 to 1995 engines). I realize that answers.com is probably not the authority on engines, so certainly it could be wrong. But, I just have to ask.

I think it's the CPI that has the spider-thing that fails a lot.

 

If by CMFI they mean central multi-point fuel injection then I guess that is sorta correct. However, typically, MFI is an acronym to describe sequential multi-point systems and not the single injector, batch fired system that is the CPI.