anesthes

iTrader: (12)

What size injectors?

-- Joe

project89

iTrader: (1)

to start u shouldnt have to change the fuel table

just swap in the new nijectors and change the injector size/req fuel calc that will get u close , and then form there u will need small adjustments here and there to the ve table

anesthes

iTrader: (12)

He may need to change the fueling strategy. Remember, unlike the factory delco ECM the MS has two injector drivers. He should probably do two squirts alternating if they are 60s or larger.

-- Joe

junkcltr

iTrader: (1)

If he does 2 squirts alternating then he runs out of fuel under boost because during each crank rev only 4 cyls get sprayed. He needs all 8 sprayed. If he goes 1 squirt and simultaneous he gets all 8 injectors sprayed during 2 crank revs. Great, full fuel at boost..........but at idle it only gets squirted once every 2 crank revs which gives a slightly rougher idle than 2 squirts alternating. But this is the only way to get full fuel spray at boost and still be able to get an idle with a BPW that is not too small for the injectors.

I run the GM 427 ECM that has two injector drivers like the MS. When going to 57#/hr P&H injectors I had to switch from batch fire to alternating bank. I had to re-code to do this so that at low BPWs it does alternating bank. When the BPWs hit a big enough value (3ms) I switch to batch fire. This allows all 8 cyls to get squirted 100% of the crank rev.

Not sure why MS has not gone to this style of squirting. Seems like all one can do is pick one fuel strategy. If he goes batch fire then it is too much fuel at idle and low rpm. If he goes alternating bank then it is not enough fuel under boost/decent HP due to only squiring 4 cyls every other crank rev. If he goes single fire, then that is squirt all 8 cyls only once during 2 crank revs. If I had MS, this is what I would pick becuase it allows the decent PW at idle and allows a full 100% squirt at decent HP. The downfall is slightly rougher idle compared to the alternate bank fire at idle.

Overall, will MS I would pick the single fire mode (squirt all 8 cyls every 2 crank revs). In MS terms, this is 1 squirt simultaneous.
If they ever upgrade this, they could have a alternate bank (squirt 4 cyls every crank rev alternating the 4 cyls per crank rev) and switch to batch fire (all 8 cyls squirt every crank rev) when PWs get large enough in alternate bank mode.

anesthes

iTrader: (12)

It's not a stock ECM. In the upper RPM it will add injection events via a feature called EAE lag compensation.

He wants to set the fueling strategy for the most stable idle possible with the large injectors.

I asked the same question to the developers before I truly understood how the MS does it's fueling. Rather than having a magical threshold between async and quasi or whatever GM calls it, they have a larger fueling function compensate.


-- Joe

junkcltr

iTrader: (1)

.

junkcltr

iTrader: (1)

It just dawned on me that the alternating will allow the injector to spray during the next crank rev if needed. Duh! I went through this with the re-write I did.

Yes, 2 squirt alternating is best for the big injectors. Should give best idle BPW and stability and provides fuel for max HP.