Jump to content

Boost control and fuel / ignition map change from a rotary switch


CamB

Recommended Posts

Hi

Perhaps to start with how I think that boost control by potentiometer works, as if I have this wrong most of what I have written below is useless:

- connect potentiometer to provide 0-5V to AN Volt 4 (I will use 4 - I realise it can be any AN Volt input). Setup as a 0-5V input
- set up boost target in closed loop at 0V through 5V (on Y axis) at desired boost levels
- turning the potentiometer changes the target boost setting.

If I've got this right, my idea for comment is below. My goal is to have position 1-3 on a rotary switch as low/mid/high boost on 98RON, with position 4-6 as low/mid/high boost on E85. I think I can do this with a single switch (and more importantly, a single input - I have a Storm):

1) I plan to use a rotary switch with a voltage divider, so that there are defined (known) steps to the boost target on the Y axis - eg position 1 is low boost (0V), position 2 is medium boost (1V), position 3 is high boost (2V), then...

2) have a Virtual Auxiliary Output which switches when AN Volt 4 is > a threshold (ie the midpoint - 2.5V)

3) switch to a second boost map using the Virtual Aux Output when AN Volt 4 > 2.5V, and repeat the table with position 4 / low (3V), position 5 / medium (4V), position 6 / high (5V). I'm not sure its critical to have this on two maps, but it feels ... tidier ... given the below

4) switch to the ignition map #2 and fuel map #2 for E85 when AN Volt 4 > 2.5V, using the Virtual Auxiliary Output 

Would this work? I have tried it in PC Link and it looks like I can make settings to accomplish the above. Note: I plan to measure the voltage output from the rotary switch - to be precise. 

Of course I'll need new injectors and to confirm my fuel system works with E85, etc etc, but I am more focused on the possibility of using the Virtual Auxiliary Outputs and defined steps on the switch as a way of creating a 'mode' switch. For example, I could have position 1 as low boost and no motorsport features.

Supplementary dumb questions:

a) I see fault settings under the analog inputs. It looks like a fault is triggered if 0V or >=5V is supplied into an AN Volt channel. Will this cause problems with my plan?

B) Wiring up a 'normal' SPST toggle switch to a DI (eg to turn on logging), switching to ground, what should the settings be?

Function = GP Input
Switch type = Toggle
Pull up = ON
On Level = Low
Active edge = [falling?] 

Link to comment
Share on other sites

 

For what I've suggested above, it occurs to me I could also have a 3 position switch and a toggle that switched a resistor from between pole 1 of the rotary switch and 5V to between pole 3 and ground. I might prefer it that way (Toggle for fuel, rotary switch for boost). Yes ... It's a lot of effort to save an input.

Extra question - should the ground for the switch be sensor ground in the ECU, or is grounding to the chassis ok?

Link to comment
Share on other sites

  • 1 month later...

Minor update to say thanks - the above gave me enough confidence to spend the time making the rotary switch.

I used 1k ohm resistors between positions and I think a 510 ohm one between each of pole 1 and 5V and pole 6 and ground. This had the effect of making the switch go in steps from about 0.45V to 4.54V (avoiding any error issue).

It then works just like I hoped (at least on the bench/in PCLink - I am a long way from having it going in a car...) for switching between 3 boost levels on each of two boost maps, with boost, fuel and ignition table #2 all switching when the switch went from position 3 to position 4.

Can see how this would be pretty useful as a 'mode' dial with enough creativity and virtual auxiliary inputs.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...