k24 VVT PID help target vs actual

[HuxRacing]

 The issue is my vvt lags behind the target. I have attached a log and a tune file. Even 1 -2 degrees costs me about 5-10whp in the midrange.  I can switch to "custom" values but wish I knew what the "default" values were to start from there.  Look at cam 2 location on high lobe, vtec is on at 5900.  Combo is a 4Piston k400 on e85. Made 332/216 normally aspirated.  Any help is appreciated. 

run37.pclr run37.llg

[Adamw]

The current "hard coded" default PID values will be shown if you change to custom PID while online.  

It looks like for K20 mode the defaults are P=4.00, I = 0.05 and D = 17.00.  Max clamp 60% and min clamp 10%. 

Looking at your log your control looks pretty typical to me and I dont think you will get a large improvement.  Stepping the target from 25 to 33deg in 100RPM (~100ms) is unlikely mechanically achievable, you have mechanical inertia and small orifices for the oil to pass through which restrict how fast things can move.    

Upping the max DC clamp from its current 60% may help get it initially moving a little faster, and possibly more I and less D will help reduce the rounding off effect you see as it approaches the target after the step change.  You may be able to drop the filter setting a point or two for a further small response increase.  But remember with any PID system there is always a balance between step response, overshoot, control stability and the mechanical constraints.  i.e you cant make a cruise ship turn like a ski boat no mater how reactive the control system is.

[HuxRacing]

Adam,

Thanks, I will give that a try.  The response seems equally slow advancing or retarding the cam so I hope some can be tuned out. You can see in other areas of the log where response is in tenths of a second and makes the full swing. 

Eric Hux

[Adamw]

VVT is always slower in one direction than the other.  With an intake cam to advance you have full oil pressure pushing oil into the actuator, for retard the solenoid just closes and the oil has to drain back out through a small orifice by itself, there is only the torsional load on the cam from valve springs etc pushing it home, there is no hydraulic power. 

[HuxRacing]

I just wanted to update this. I sorted the VVT PID settings. Initial k20 settings are P 4, I .05, D 17. I ended up with P 5, I 1.5, D 17. This gave me a vvt target to actual that was never off more than a fraction of a degree during a dyno pull. The issue is the intake cam needs to drop from 33 down to 25 at the top of the pull and the default settings lagged about 3 degrees.