gear based dome control

[Blue 12]

Im not sure if Im reading something conflicting between the manual and tuner studio or not. can I use dome control in open loop with the gear based targets? if so, is the target table used as a throttle vs rpm ramp?

[jsmcortina]

Yes.

All of the existing boost switching and blending can now be used with dome.

James

[Blue 12]

thanks James, can you give me an example of what to put in the target table, or tell what what happens with say a 0, 100 or 200 value input?

boost question.jpg

I know roughly what maximum i want in each gear, just not sure how to ramp it in. if the table is a % of the gear target, or if the gear target adds to the table etc.

[nathaninwa]

You use the blend boost function. Table one is minumim boost, table two is maximum boost. The blend curve shares a relation between the two tables. So if target 1 is 150kpa and target 3 is 200, using 50% for target 2 the commanded boost would be 175. Same gos with dc in open loop

[Blue 12]

well minimum boost "target" will be spring pressure in first gear. I want to add more for each gear, preferably ramped in like you can with an AMS boost controller

say I have an 8 psi spring in the gate, would that be max target for the top of the table? (156?) and then if i want to run 170 kpa in second gear i put 184 as my second gear target as it would average to 170?

boost question.jpg

[nathaninwa]

There maybe some confusion here

We have two tables to work with, that are tps versus rpm. If you want your spring pressure for first gear, then yes, the 100% row will get 156kpa (if that what it works out to be, seems right). Then let's say you want 256kpa as your 4th gear target, boost table two will get 256 in the 100% row.

Now in the blend curve based on gear, first gear will be 0%, or all table 1, 4th gear will be 100%, or all table two. If you want 170kpa for second, do some math and put the second gear ball around 15% I think. This will blend 15% from target table 1, to target table 2

[Blue 12]

Im not seeing anywhere for blend curve? just gear specific targets, which seems to be what I want?

boost settings.png

[nathaninwa]

Ok. There are two types of boost by gear. The one you have chosen in the last picture. Those targets are set per year and can not be changed based on tps. You've been showing picture of the target tables wire boost fan based on tps

Each is fine I've ran both ways

If you want just boost by gear targets with no tps blending then use the gear type. If you want to blend each table target based on gear position which allows tps blending look for the blend table option under the boost table switching menu. Then under the tables options pick the boost blend and choose gear for that one

Edit, I need to look at the dome control. Typically you can't run boost by gear targets in open loop, only blending the boost target dc tables by gear

[nathaninwa]

I want to look up the dome control PDF and fully understand this more. I'm wanting to try this out this year

[jsmcortina]

Dome is covered in the Setting Up manual.

James

[Blue 12]

it seems to be missing the part about gear based stuff

http://www.msextra.com/doc/pdf/Megasqui ... Up-1.5.pdf

using ctrl f (find) brings up 35 "gear" locations in the text. #13 is in the EAE section. #14 is in the boost section, and #15 is gear based spark table switching.

this is everything the text says about gear in dome control.


4.17.7 Boost Dome Control
Particularly in drag-racing, it is common to use a compressed CO2 supply to forcibly pressurise the top
portion of the wastegate actuator to achieve boost levels above spring pressure.
Two three-ported solenoids are required as well as an additional pressure sensor to monitor the dome
pressure. The 'vent' port on the 'fill' solenoid must be plugged. Restrictors will likely be required on fill and
empty solenoids to avoid overshooting.
The compressed gas supply is typically CO2 and needs to be regulated to a pressure a little above the
(c) 2014-7 James Murray 2017-01-16 Page 107/171
Megasquirt-3 Setting Up 4:Advanced topics
maximum dome pressure required. For testing, compressed air works fine too.
Keep the hose between the MAP sensor and the wastegate as short as possible for better control.
4.17.8 Dome control concepts
Dome control is linked to the main boost control system in one of two fundamentally different ways:
a. Open-loop
The target table is dome pressure targets. The manifold pressure (MAP) is ignored. The dome
control system adjusts its solenoids to achieve the dome target.
b. Closed-loop
The target table is manifold pressure (MAP) targets. The closed-loop system adjusts the dome target
to achieve the target MAP. The dome control system adjusts its solenoids to achieve the dome
target.
a. Open loop
The "boost target" table is actually "dome target".
Boost target feeds directly into dome system. All existing modifiers (boost vs. gear etc.) work as before. This
mechanism is used by other ECUs on the market. There is no reference made to engine MAP, so it is up to
the tuner to determine what dome pressure they need.
(c) 2014-7 James Murray 2017-01-16 Page 108/171
Megasquirt-3 Setting Up 4:Advanced topics
b. Closed loop.
The "boost target" table is the target manifold pressure (MAP).
The boost control system attempt to control the dome pressure to achieve the desired target boost.
A bias table is used that gives a 'hint' to the code of the needed dome pressure for a given target boost.
(c) 2014-7 James Murray 2017-01-16 Page 109/171
Megasquirt-3 Setting Up 4:Advanced topics
4.17.9 Dome MAP sensor configuration
The pressure sensor must be configured through the "Generic Sensors" system and works in absolute
pressure. i.e. approximately 100kPa is atmospheric pressure.
The following screenshot is for a GM 3bar MAP sensor.
(c) 2014-7 James Murray 2017-01-16 Pa