Sequential fuel injection (sfi)

Canada · Post by **Canada** » Tue Mar 19, 2002 6:04 pm

What does sequential fuel injection do for me?

3100SFI · Post by **3100SFI** » Tue Mar 19, 2002 7:06 pm

It fires each injector individually. It's more efficient than a multi-port which fires three injectors at a time.

Guest · Post by **Guest** » Tue Mar 19, 2002 10:26 pm

That's right. Also, it gives you quicker response and also better gas mileage. It's the best type of fuel injection to have.

Guest · Post by **Guest** » Wed Mar 20, 2002 6:20 pm

I may be wrong, but I thought all GM mpfi was what they called batch-fired, meaning all the injectors in one bank fire at the same time. I think dis ignition fires two plugs at the same time. one on the compression stroke the other on the exhaust stroke. I think sfi is more efficient. I believe since 96 all GM engines are sfi.

Guest · Post by **Guest** » Wed Mar 20, 2002 11:33 pm

Yes, SEFI fires each injector individually. MPFI fires 3 injectors at a time...Not spefically all in one bank, but the first 3 in the firing order, then fires the next 3 in the firing order. They could be all the same bank or not.

I'v never heard of DIS fireing 2 plugs at the time...Maybe I could be wrong, I'v never looked into this, but I'm just curious now...

Guest · Post by **Guest** » Thu Mar 21, 2002 1:15 am

Hi, this stuff is interesting to me. I looked up the ecm pinouts on a 2.8L engine. On the vin W it lists two injector drivers. ecm pinout C11 is the driver for injectors 2,4,6. ecm pinout C12 is for injectors 1,3,5. The drivers don,t know which cylinders are which so 2,4,6 fire at the same time and 1,3,5 injectors fire at the same time. On the dis ignition, the two plugs on each coil fire at the same time. Among other things it is called waste-spark ignition because of the firing pair, one is always on the exhaust stroke. You can go to motorage.com and click on the troubleshooting link, then type in dis ignition in the search box, it gives alot of good info on dis ignition. If my info is in error, let me know, that is how I learn. thanks

Guest · Post by **Guest** » Thu Mar 21, 2002 1:43 pm

the Dis system does fire both plugs at the same time--remember basic electricity--it is trying to get back where it came from....it fires with a positive charge from say cyl #1 and fires the plug--the energy then travels through the block and back out the opposing plug on that same coil pack but that plug fires with a negative charge--waste spark...and then goes back to the coil pack ---understand now???

3100SFI · Post by **3100SFI** » Thu Mar 21, 2002 2:47 pm

In simpler terms: more voltage useage in the cylinder on compression stroke than in the cylinder on exhaust stroke.

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