[Air Man]

Can someone tell me what the relationship between "Vane target" and "Boost target".

How do they interact with each other?
If I wanted to get 30psi of boost using EFI, do I change the boost target, the vane target, or both?

I think that the boost is controlled by the vane target and the CEL is controlled by the boost target (boost target +/- C804, C805). Am I correct?

 

[Max Power]

It's probably best to leave the vanes alone at this point in time. You can increase boost without changing the vanes.

 

[lakingslayer]

Use the boost target table. It will give you everything you need.

 

[bobo]

I have had the best luck changing the boost target. I have changed everything and that seems to net the best results. Actualy, I have it set too high right now. I'm turning it down as we speak. Make sure to have an EGR blocker plate. Weird things happen at 30psi without one, even with EGR turned off.

 

[DURAtotheMAX]

Yeah bobo I noticed I got this weird whooshing/shreiking when Tony and I were driving my truck around and really getting into the throttle. Not just the litlte whistle spool up....it was soemthing I havent heard before...

--Ben

 

[Wasted Income]

I heard that sound, too.
Not a sound I want coming from my daily driver...

 

[Air Man]

Thanks guys.

 

[bobo]

Ben, On a lift or while on the go peddal? You still getting 1093's?

 

[Fingers]

Target Vane position is what the ECM will set the vanes to when you command a given fuel rate at a given RPM. Not unlike leading a target.

 

[cit1991]

I asked this a few posts back too. I'm not sure anyone knows for sure. Vanes are varied to hold the boost target pressure. So why is there a vane target map? We do know that you do not need to vary the vane target map to raise boost...just the boost map.

The only thing I can think of, is that it's a feedforward term in the boost control algorythm.

I.e. vanes are always varied to hold a boost target using feedback from the MAP sensor. (subject to max and min clamps) But when fueling or rpm changes, the vane target table tells the computer how (and how much) to change the vanes, before the boost itself changes. To make it respond faster, and hold boost more accurately.

Those of you with industrial controls experience, will recognize this as a feedforward term in the PID equation.

I'm not sure if any of this is right, but I'm watching it to see if I can verify this.

 

[Fingers]

It smacks more of a predictive scheme than a real PID. Shoot the target position first then trim in feedback mode. What is missing is the learned response portion. I would love to see the code.


Either way, The postion tables can be used to improve response.

 

[lakingslayer]

It smacks more of a predictive scheme than a real PID. Shoot the target position first then trim in feedback mode. What is missing is the learned response portion. I would love to see the code.


Either way, The postion tables can be used to improve response.

That's what I was thinking but haven't started playing with it yet. I did some logging of the vane position and boost quantity and it was kind of cool watching the vanes open and close and the resulting boost.

 

[Fingers]

There is another possibility. That being that the table is a check for turbo perfomance. Given a target boost of X the Vanes are expect to be at Y to achieve the boost when burning a given amount of fuel at a given RPM.

In other words, it does not affect the boost.

 

[lakingslayer]

I guess we'll have to play with it and find out.

 

[Flashscan]

The vane position is so, so, so confusing. It is indeed a feedback based system, move it to here, check it got there, adjust as needed, I don't understand 100% what all the tables are doing, there is many more in that portion of the code, but right now, I am not sure what they are doing apart from it looks like a feedback loop adjustment.
I think of it as a way to change the repsonse of the boost more than how much boost to obtain.

Cheers,
Ross