Tuning ACU with Brucato Software

[PanRonnie]

I think you probably don,t have your water pressure sensor properly calibrated
You have to tell the software what the value is at what voltage
This can be anything from 0 to a 1000 psi
This depends on your sensor
What sensor do you have make and type number

[PanRonnie]

[CI STV]

looks like a hybrid 56lb horn curve we have. A mash of a Drag and 280. Looks very close.

Yep, the A13 curve I have in my box (from Diamond) and the A6 curve that came with the software look almost identical, although I haven’t gone through it line by line as yet. Still trying to figure out why they gave it to me with a 10K limiter in it, since I was told it should pull strong to 11,000. Also, the main potentiometer was cranked up to 12% and the motor was pig rich. Would’ve thought that since it was dyno-tuned, they would’ve used the Brucato software to build a custom map, rather than use a screwdriver.

[CI STV]

I think you probably don,t have your water pressure sensor properly calibrated
You have to tell the software what the value is at what voltage
This can be anything from 0 to a 1000 psi
This depends on your sensor
What sensor do you have make and type number

The WP sensor I have is an AiM sensor and I simply selected the part number for that sensor from the drop down menu in the RS3 configuration tables. I assumed that was all you have to do and the software would have the correct formula baked in? I’ll double check it though. I think it must be close, since it produces about 1 psi at idle and anywhere from ~15-19 psi at WOT at high RPM and pretty much increases linearly with speed.

[PanRonnie]

Then those values you circled in red are probably the milivolts values
as long as you see the correct values in the graph i would not wurry about them

[CI STV]

Then those values you circled in red are probably the milivolts values
as long as you see the correct values in the graph i would not wurry about them

Thanks. That makes sense. Just to be clear, I’m not trying to do anything with the water pressure settings, or any of the other other analog inputs. The only thing I wondered about was the MERC VAC setting in the ECU stream, since that only reports 50-100 (%?) in the datalog. But, to me, throttle position is not really that important and if I want to log TPS, I could add an external TPS from AiM and connect it to an external channel anyhow.

[PanRonnie]

This is a graph of my last time out last year
still in break in so taking it easy
the greener the color means the more total time the engine spend there
these are tru Kpa barometric pressure values unlike yours which will be double values
so i idle about 90 Kpa but once plane my map pressure drops to 75 Kpa at 3700 rpm
that is why trying to do a two stroke with a throttle as load is a nightmare
the brief periods of 7000 is the prop coming loose as i hop over the waves

[CI STV]

Okay, just to add some more “data” for us to consider, below are a couple of screenshots of the two fuel graphs I have, one of them being the Drag A13 SVS (with the rev limit changed from 10k to 11.5k) and the other being the Drag A6. Can you spot the differences? Cause I can’t, although I haven’t gone through them line by line.
The one readily apparent difference is the enrichment offset for groups 2 and 3 injectors. Looks like mercury thought that the bottom cylinders needed a lot of additional fuel with the SVS? Note that at 10,500, the tune is commanding an additional 6% on the fuel for the two group 3 (bottom?) injectors…
As a side note: I always wondered why some folks run a much thicker stack of spacers on the bottoms slots on their SVS, whilst on others, like the Diamond manifold I have, the inlet runners are the same length? Maybe the fuel offset is another way of balancing those lower cylinders?
Anyways, here are the two fuel maps:

[CI STV]

The other thing I’m guessing is that since the fuel map only goes to 10,500rpm, the ACU extrapolates what fuel is needed at, say, 11,000?? Because I’m ASSuming that since it had a 11,500 limit, it still has to provide fuel for that extra 1000rpm?

[PanRonnie]

This is from an 849 ecu with the drag intake if i remember correctly
The fueling of group 3 is a percentage of group 1 the same as the brucato but a 3 d table
This one adds 25% to the bottom cylinders
This can't be to keep them in one piece
Those cylinders apperently make more power than the others
Now the reason why they did what they did is probably going to be a mystery
My guess is that they found it beneficial to have 3 torque peakes instead of one going through the rpm range
Otherwise they would have put them on all 3 groups
There is an exhaust cover bolt above each cylinder exhaust port
It was one of the things i wanted to do is a hollow stud with a hole in the center of the block hole to data log the individiual exhaust port heat so you could tune per cylinder
But with even spacers the torque curve and fuel demand should be the same for all cylinders
But you might wanna contact diamond marine about it

[CI STV]

This is from an 849 ecu with the drag intake if i remember correctly
The fueling of group 3 is a percentage of group 1 the same as the brucato but a 3 d table
This one adds 25% to the bottom cylinders
This can't be to keep them in one piece
Those cylinders apperently make more power than the others
Now the reason why they did what they did is probably going to be a mystery
My guess is that they found it beneficial to have 3 torque peakes instead of one going through the rpm range
Otherwise they would have put them on all 3 groups
There is an exhaust cover bolt above each cylinder exhaust port
It was one of the things i wanted to do is a hollow stud with a hole in the center of the block hole to data log the individiual exhaust port heat so you could tune per cylinder
But with even spacers the torque curve and fuel demand should be the same for all cylinders
But you might wanna contact diamond marine about it

Both the A6 and A13 are 849 ECUs. (Per chart below)
As far as I can tell, the A13 is later curve for the 2001+ Merc Drag with the Blue Merc SVS, which I presume required the different (additional) high rpm fueling for the bottom cylinders?
The curious thing is that the chart shows both having an 11,500 rpm rev limit, but the map that came in my ACU from Diamond had a 10K limit and so did the A13 map I got from Brucato directly.
I remember distinctly that Marty told me that my motor should pull 11,000, but that wouldn’t be possible with a 10K limit…

So I was surprised to find it had the same fuel curve and limiter as apparently what Brucato sells as the A13 map for their ACU. The only thing I noticed was that the main potentiometer was set at 12%, and my engine was running very rich with that.

[ironhead stv]

did you get it working ?

[CI STV]

did you get it working ?

I haven’t had chance to test the boat since I made the changes. Will post up when I do.

[ironhead stv]

What setting are on the Senitivit and Volume

[CI STV]

What setting are on the Senitivit and Volume

This is where its at now. I didn’t mess with any of the potentiometers other than the Main pot, which I’ve leaned out (turned CCW) by 3%.