ISCV override alternatives outside of the idle range

[DerekAE86]

I've been overriding my ISCV via the anti-lag settings to make sure its shut as soon as I touch my pedal and on overrun so I can produce more vacuum to keep my brake booster topped up.

But I understand that when the anti-lag options are enabled it also disables overrun fuel cut?

This hasn't been an issue because I've had fuel cut off while fiddling with my tune, but I'd like to turn fuel cut back on soon so need another way to control my idle valve outside of the "idle" range.

Currently I have a Virtual Aux setup for my ISCV override that is TPS > 1% OR (TPS < 1% AND Wheel Speed > 25km/h)
This captures both situations where I'm actively on the accelerator or in an overrun state.

I then use this Virtual Aux as the anti-lag enable with all options off other than ISC override to close the valve completely.
Then as soon as Wheel Speed drops under 25km/h the Idle Control takes over if TPS is still < 1% and opens the valve as required.

My only thoughts is to disable the idle valve output and then create a GP PWM output that controls the Idle valve based on the Idle Position runtime or my "override" Virtual Aux. The issue with this is I have a 3-wire ISCV so I would have to create 2 GP PWM outputs. And I'm just not sure how it will work if I set the Solenoid type to none or have a Solenoid type selected but the output set to none?

[Vaughan]

3 minutes ago, DerekAE86 said:

But I understand that when the anti-lag options are enabled it also disables overrun fuel cut?

Yes

4 minutes ago, DerekAE86 said:

My only thoughts is to disable the idle valve output and then create a GP PWM output that controls the Idle valve based on the Idle Position runtime or my "override" Virtual Aux. The issue with this is I have a 3-wire ISCV so I would have to create 2 GP PWM outputs. And I'm just not sure how it will work if I set the Solenoid type to none or have a Solenoid type selected but the output set to none?

The outputs are operating synchronously to each other in the push/pull ISCVs so this wouldn't work well

 

If you set your ac, fan, power steer, gear drive and dash pot offsets to 0 and then have the base position table go to 0 when idle is in lockout then it should hold 0% when in lockout.

Alternatively install a vacuum pump to supply your brake booster with a consistent vacuum regardless of engine vacuum.

[Adamw]

I think if you set up antilag enable to very high RPM so it never activates, set cyclic mode to sys armed, then use the cyclic ISC override table instead, this will still allow overrun fuel cut to work.  

[DerekAE86]

41 minutes ago, Vaughan said:

If you set your ac, fan, power steer, gear drive and dash pot offsets to 0 and then have the base position table go to 0 when idle is in lockout then it should hold 0% when in lockout.

That's not really ideal since I want those offsets. I might be able to live without the fan and dashpot offsets, but not the AC one.
And that table can't be edited so I can't give it a 2nd axis to reference my virtual aux runtime to get the benefit of both either.

3 minutes ago, Adamw said:

set cyclic mode to sys armed, then use the cyclic ISC override table instead

I hadn't even investigated cyclic mode - I'll look into this, thanks.

[DerekAE86]

using cyclic instead worked a treat. however it has now left me with another very serious issue...

...i setup a latching toggable momentary switch in logic but didn't know what to do with it so assigned it to activate the second antilag ignition trim table and retard my timing by 40 deg when in overrun to see how obnoxious i could be...

so now i don't know what to do with it hahaha

[dx4picco]

What I did was to have the idle base table as a single row, depending on ECT, then put a Y axis with the like of a virtual aux that activated depending on your needs. for example speed like you want. an put 0s for example on that second line.

I did that but on a switch that adds 30 steps on a stepper IACV to get it more shut and increased engine brake

[DerekAE86]

I'm not sure that reliable though. I'm pretty sure that as soon as you enter the lockout ranges the idle control system stops moving the solenoid regardless if the base position is updating in the background.

[DerekAE86]

Just incase someone else finds this topic. Now the G5 has been released and the G4x firmware updated with additional Anti-Lag options you can utilize the AL ISC Override AND have functional Fuel Cut without having to use Cyclic Idle and retaining the ability to have Dual AL tables for silly things like crackle tunes.

Just disable the main Overrun Fuel Cut under Fuel and instead create a Virtual Aux for the same conditions (EG: TPS < 0.5%, 0.5s on delay) then use that as an Axis on the newly added Anti-Lag Fuel Cut table.

Put 0s across the entire RPM range when your Virtual Aux is inactive so there is no fuel cut, but then put the desired Fuel Cut% in the RPM ranges when the Virtual Aux is active. Using this method you can have 100% cut at high RPM but then ease the fuel back in as you get close to the desired RPM to have full fueling again; around 1500RPM for example.

If you were using Ignition Trim in the default Overrun Fuel Cut settings you can also implement this in the AL Ignition Trim table using the same method as above.

An added bonus of this is you can add a speed or gear parameter to your Virtual Aux so fuel cut never happens at less than 30km/h or 2nd for example to prevent jerkiness at carpark or traffic jam speeds where you might have otherwise been going in and out of fuel cut before.