Aux IGN#3 as Vtec Output, Switch Off Timer?

[Ben.C]

Hi,

 

I was on the dyno last night and had a problem with my Vtec engaging and disengaging very quickly, it sounded like a limiter. I'm 95% sure this is hysteresis. 

I'm running an Atom and it's fully populated hence why I'm using an unused IGN channel as the Vtec output. When I tuned the last car I built, I had a Fury that had a setting called switch off timer. I had this set to just 0.2s and that was enough to have vtec work properly. 

Is there a way to use a timer, like timer 1 as this switch off delay? I'm only able to have 2 switch conditions for this channel, so it would be condition 1, RPM>5500. Condition 2, timer 1. Switch condition 1 OR 2.

My thoughts are to set timer 1 trigger activation as AUX IGN#3 (my vtec output). When I hit 5500rpm, AUX IGN#3 engages, the timer starts and stays on for around 0.5s, then turns off. This way I'll have a 0.5s minimum Vtec engagement window which should get me out of the hysteresis. Now the critical part is the timer must stay on if AUX IGN#3 tries to turn off based on RPM alone.

Example:

• Engine speed hits 5500RPM
• Condition 1 is active (RPM >) and triggers timer 1 for condition 2 active
• Vtec engages, timer starts
• Engine speed has a bit of hysteresis condition 1 is no longer active
• Condition 2 stays active for 0.5s, engine speed leaves the hysteresis range, condition 1 is active again
• Condition 2 no longer active after 0.5s

Can someone please let me know if this is possible, and if so, how to set the timer up?

 

 

Edited September 9, 2023 by Ben.C
added example

[DerekAE86]

What you can do is utilize a Virtual Aux as a GP Output for your RPM condition, change the Timer to "Reset when On" so it will be held at 0s when the Virtual Aux is active and then start counting when it goes off.

So you can then create an OR condition for the Ign output to be either Virtual Aux active or the Timer less than 0.5s.

The timer will count up to 10s and stop there until VTEC activates again and it will reset it to 0s and hold it there until the RPM condition is no longer met.

The bonus of this method is you gain 2 extra conditions on your Virtual Aux - so you could put a TPS or MAP condition to prevent VTEC coming on without load.
Or even a ECT or Oil Pres condition to provide some engine protection.

[Ben.C]

Wow thanks so much for the reply.

I'll definitely give this a try.