SFI vs MPFI on 3100?

[dnalbach]

Newbie alert....

I just got my first 60v6 car, a 95 Cierra Cruiser with a 3100 in it. This is the Gen3 engine with the Sequential Fuel Injection according to all the specs I see on the Internet. I am seeing a lot of mention on this site of Multi-Port Fuel Injection for the 3100. What year did that change take place? What is the difference? Are there any power gains?

[sharkey]

sfi started on the gen 3 motors when they first came out. its mainly for fuel economy. it is only sfi under 3000rpm, any higher and the ecm reverts back to mpfi, so no power gains.

[Superdave]

Unplug your cam sensor.... Bam! MPFI


i never had problems running my 3400 as MPFI, got around 17-18 MPG. It did idle like a gen2 V6 tho.. my '04 grand am GT idles MUCH smoother...

[3100 MPFI]

When I built my 3100 for my Cutlass Supreme, it was never intended to be SFI. I built it (and as my sig name states) as a 3100 MPFI.

I still get 35-ish MPG on the highway. In the city, I get a LOT less, but I tend to stay on the gas a lot.

The first year of the 3100 was 1993 (in the Cutlass Supreme ONLY).

In 1994, all the cars went to 3100's (except for the Chevy Lumina. The Lumina did not get the 3100 until 1995 when the exterior was redesigned).

It makes no real differance how the engine is run. The SFI is only good for driving like a grandma. That is the only way it really saves fuel.

I went with MPFI because I was building a 2000 3100 to go into a 1988 Cutlass Supreme, and I did not want to wire the entire car for OBD2.

[Guest]

When I built my 3100 for my Cutlass Supreme, it was never intended to be SFI. I built it (and as my sig name states) as a 3100 MPFI.

I still get 35-ish MPG on the highway. In the city, I get a LOT less, but I tend to stay on the gas a lot.

The first year of the 3100 was 1993 (in the Cutlass Supreme ONLY).

In 1994, all the cars went to 3100's (except for the Chevy Lumina. The Lumina did not get the 3100 until 1995 when the exterior was redesigned).

It makes no real differance how the engine is run. The SFI is only good for driving like a grandma. That is the only way it really saves fuel.

I went with MPFI because I was building a 2000 3100 to go into a 1988 Cutlass Supreme, and I did not want to wire the entire car for OBD2.

Just wanted to mention, the Cavalier also stayed genII 3.1 in 1994.

[3100 MPFI]

K Thanks. I have to admit that I mostly only look at the W-bodies. I found out about the 1003 3100 by Accident. I was looking for an air duct for my Cutlass Supreme. In 1994, they changed the front crossmember, so I can't use a 3.1 airbox (the airduct goes WAY past the throttle body), but the 1994 3100 airbox does not fit because of the redesigned front crossmember.

I found a 1993 3100 in the yard, and got the duct, airbox, and mount for it all.

I thought it was a 1994 until I noticed that it did not have an airbag. I looked at the vin number, and saw it was a 1993, and that is when I started researching the 3100 more.

I think that Chevy carried over everything for one year anyways. I saw a 1996 Lumina with a 3100 that did NOT have roller rockers.