Switchig from semi to full sequential - needs more fuel?

[abeebe718]

Setup: BMW m60 v8, MS3X, stock cop, 60-2 crank, 2wide 2 narrow cam,

http://www.msextra.com/forums/viewtopic ... 31&t=65902
Here's some more background, trouble getting it started

so I drove around for about an hour today in semi sequential (rising edge cam, cam fault is on) mode letting the VEAL smooth out the fuel table. Running great, idles fine, etc. I get home and switch back to full sequential (polling on tooth 10) and it immediately starts running really choppy. Having to give it throttle to keep it alive. Turn the auto tune on and it wants to start dumping fuel in the cells where it had just leaned out. Do this for a few minutes and it gets much smoother. My question - Is it normal for there to be a much higher fuel demand in full sequential mode? As in cell values going from mid 60s to 80s? Computer is dead, will attach msq later. Of course I didn't datalog when I made the change...

[billr]

There should be little (no?) change in the VE table when switching form semi to full-sequential. After all, "VE" stands for Volumetric Efficiency", how well the engine breathes to fill the cylinder with mixture. That can't change without making some physical change to the valving, induction system, bore/stroke, or rod length/off-set.

This is most likely a dead-time issue.

Is yours a typical port injection, where fuel can "mellow" for a bit upstream of the valve? I suppose if you have injectors so close to the valve that the spray pattern can go right through the valve/seat opening, then fueling could change between semi and full. Note that the VE has not really changed, but the VE table may be the only tool to account for radically different vaporization of the fuel.

[kaeman]

Another thing you might check, is your injector timing table, mine started out 360 everywhere and end of squirt for the setting. I started playing with the injector timing because a friend uses holley systems and we were comparing differences between the systems, he had found that his engines like the injector timing early in the cycle. The fuel we have in California is crap, and I was having the odd smell to the exhaust that California fuel will have, I was told to try changing my squirt timing to help.... I ended up at 265 for the end of squirt timing but the bad smell went away and the engine ran better and I actually had to remove fuel from my ve table. It may be worth checking into on your engine. make the changes in 5 degree changes see if you notice any change, move a little farther, until the engine runs way worse or way better, if it runs worse, try moving the timing in the other directon. when you hit the sweet spot your engine will let you know.

[red-racing]

how the amount of fuel into the engine changes vs to injector timing is to me a big question.
I have also tried change from full seq to batch fire but no significant difference

[slow_hemi6]

Without a msq, it's rather hard to give an opinion.

[abeebe718]

Thanks for the replies. Someone else has also suggested it may be an injector timing issue so hopefully that will be the case. Current table is 360 across the board. heres the msq...

turbo m60.msq

[slarsen]

I am also interested in the injector timing table numbers and how they are determined.