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MFI? SFI? TPI? EIEIO?


Guest Anonymous

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Guest Anonymous
Posted

L27 = 3.8L Gen I

 

That's what I get, but is there a difference between MFI (which is what the RPO says) and TPI (which is on my engine cover). Then the Engine Page on the w body front page uses Sequential, which is something else. Huh?

Posted

TPI = Tuner Port Injection. Which is the Intake design of the engine.

 

MPI = Multi-port-injection. Which means there is one fuel injector per cylinder.

 

SFI = Sequential Fuel Injection. Which means the fuel injectors fire in sequence with the engine's firing order.

Posted

I think I know the difference between MPFI ( multi port fuel injection) and SFI (seqential fuel injection). On MPFI, ALL the injectors fire at the same time, and the fuel sits on the closed intake valve for a split second until it opens. On SFI, the injectors fire independently from each other, only when it's intake valve is open. Correct me if I'm wrong....

Posted
I think I know the difference between MPFI ( multi port fuel injection) and SFI (seqential fuel injection). On MPFI, ALL the injectors fire at the same time, and the fuel sits on the closed intake valve for a split second until it opens. On SFI, the injectors fire independently from each other, only when it's intake valve is open. Correct me if I'm wrong....

 

Thats right, also all SFI engines are MPFI. SFI is fuel econ technology. At WOT, when theengine is cold, there is a bad cam signal or in limp home mode the pcm defaults to MPFI.

Guest TurboSedan
Posted
On MPFI, ALL the injectors fire at the same time

 

i thought they were fired 3 at a time (batch fired)? IOW each injector on the front side gets fired and then the other bank of injectors gets fired?

Posted
On MPFI, ALL the injectors fire at the same time

 

i thought they were fired 3 at a time (batch fired)? IOW each injector on the front side gets fired and then the other bank of injectors gets fired?

 

my harness analysis confirms that they are wired as two parallel sets of three, reflecting your thought. I assume you are correct.

p.s. on 3.1 and 2.8 engines I have worked on

 

And the SFI each share a single (split 6 way) hot wire, and have seperate (ie 6) grounding wires (3100)

Guest Anonymous
Posted

That explains it. I was wondering if someone had gotten mixed up or what. Thanks!

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