dsp5 tables

[killerbee]

Hello Ross and Paul. Happy New Year!

Would it be possible to get dsp5 to include max vane position? I think this is an incredible innovation, however I am not understanding why target vane position is there. As far as I can tell, max vane position would be so much more useful. It would permit the user to program in an turbo-vane exhaust brake, which cannot be done now.

Does that require a new OS?

[GMPX]

It will require a rewrite of the DSP5 OS's and possibly make the existing DSP5 LLY OS's non compatible, but that depends how much space the extra tables take up. I will keep it in mind though, but given we only finished redoing the OS's late last year for the V2 switching update I'm a little reluctant to revisit them again so soon.

When deciding which tables to add we simply threw the question out there and based on the feedback on what was requested that is what we ended up including.

Cheers,
Ross

[killerbee]

Darn, I wish I had mentioned it sooner. I know it has been brought up in a number of threads, and figured this was just due.

Just for my understanding, and curiosity, why is "vane target" included? This table appears to be among the most insignificant to switchability value.

[Cougar281]

Hello Ross and Paul. Happy New Year!

Would it be possible to get dsp5 to include max vane position? I think this is an incredible innovation, however I am not understanding why target vane position is there. As far as I can tell, max vane position would be so much more useful. It would permit the user to program in an turbo-vane exhaust brake, which cannot be done now.

Does that require a new OS?

It can't? Funny... It works on mine in all my DSP slots...

The way I understand the DSP OS (Ross, correct me if I'm wrong) is it uses the tables in the DSP slot (ie: Target vane position) when that tune is selected, and the other tables that are in the base tune, but not DSP are used all the time, regardless of which tune is selected (ie: Min vane position and Max vane position).

The way my DSP5 tune is set up, I have min vane position set to 98% from 800rpm & up @ 0mm, and max set to 100%, same cells as min in all the applicible tables. Then I have target set to 99% in all locations, DSP included. "Turbo Brake" and "LB7 idle" work like a charm.

[killerbee]

I understand what you are saying. In reality it can be done with the boost dsp, but max vane must be set up in the main tune. Min vane should be left alone or you will have a full-time, fuel wasting, non-switchable exhaust brake..

But still, help me understand what switchable value "target vane position" has.

[Cougar281]

But still, help me understand what switchable value "target vane position" has.

Well, different boost levels specified by different tunes will need differnet vane positions, so if you have a big tune that needs a lot of boost, and a small tune that doesn't, you'll need different vane targets for each one, so you'd need that table for each position, wouldn't you?

Keep in mind, I'm FAR from an expert tuner ;)

[killerbee]

vane target has nothing to do with commanded vane position (based on my logging experience) which comes from a separate vane controller, I am guessing an integral controller of sorts. It appears to be a very transient "start point" when commanded and desired boost have a disparity. IOW, worthless IMO. That comes after 3 years of trying to find a value for it.

[LarryJewell]

Ideally, I'd like to have max and target vane tables on each dsp switch.

[killerbee]

Larry

What value is target vane position? If you can tell me how it is important, you will be the first among 30 people I have asked.

[LarryJewell]

You need the target table in addition to the max table, they do work together, I feel that both tables would be of value on the dsp operating system, especially for aftermarket vvt turbos.

[killerbee]

, they do work together,


I have not found that to be the case. Experiment: change all target values to 10, and go for a ride, and tell me if anything feels noticeably changed.

If this is true, that space should be freed up for something that does have a switchable value.

[LarryJewell]

I've already done that................

think about it for a minute, you still have a max table and a min. table for the vane to work within, target is just a suggestion, the vanes will still "hunt" for an appropriate position within the set parameters to make boost.

I would be for getting rid of the desired boost table on the dsp switch positions and have target vane and max vane in its place, I feel this would allow more flexability in tuning.

[killerbee]

get rid of desired boost switchability???

Are you just playing with me? :) That's 50% of the air/fuel equation.

[LarryJewell]

get rid of desired boost switchability???

Are you just playing with me? :) That's 50% of the air/fuel equation.

no, use the desired boost from the base tune, use the max and target vane table for fine tuning boost in the dsp tables.

[killerbee]

changing allowable vane position doesn't do anything to change boost. it defeats the whole purpose behind dsp, different power tunes...you need to change air if you change fuel. Vane tables can't do that.

[LarryJewell]

you might want to go test this then, I have, its easy enough to do with a dsp tune

[killerbee]

I did. Left boost constant at 20 psi. I changed max vane to 100% across the board for the "after" run. I get the same 20 psi, before/after. Exactly what I would expect to happen.

I then changed target vane to 0 everywhere. It didn't change anything, peak boost identical.

Did I test the wrong thing? It only reaffirmed that "desired boost" does, in fact, control boost using vane settings. It also proved that you can not modulate boost by adjusting vane tables, although you can increase boost capability by upping max vane, but that is not the issue, nor is it "control". It is just removing a limitation is all. This can be done in the main tune, leaving switchability in the dsp tables, using desired boost.

Let's just disagree on this one.

[LarryJewell]

I did. Left boost constant at 20 psi. I changed max vane to 100% across the board for the "after" run. I get the same 20 psi, before/after. Exactly what I would expect to happen.

I then changed target vane to 0 everywhere. It didn't change anything, peak boost identical.

Did I test the wrong thing? It only reaffirmed that "desired boost" does, in fact, control boost using vane settings. It also proved that you can not modulate boost by adjusting vane tables, although you can increase boost capability by upping max vane, but that is not the issue, nor is it "control". It is just removing a limitation is all. This can be done in the main tune, leaving switchability in the dsp tables, using desired boost.

Let's just disagree on this one.

using the max and target together, you can control boost, given a reasonable desired boost table. All I was getting at was I would rather use a constant desired boost table from the base tune and use the max and target tables to control the results in dsp tables, which is easily done. I'd hate to see what your drive pressure was at maxing out the vane table, but then thats a different topic. Ultimately, having the desired boost, max and target vane tables available in the dsp settings would be great, but i'd settle for the 2 vane tables.

your right, we'll just disagree on this one.

[killerbee]

I'd hate to see what your drive pressure was at maxing out the vane table,


identical in each case. as is vane position to obtain said 20 psi of boost. dp would have to be the same.

[LarryJewell]

and how are you reading drive pressure

[killerbee]

I'm NOT reading drive pressure. I'm using common sense. If the exact same vane position is creating the exact same boost at the exact same rpm, and the exact same fueling...

... then what do you suppose drive pressure is going to do?

[LarryJewell]

I'm NOT reading drive pressure. I'm using common sense. If the exact same vane position is creating the exact same boost at the exact same rpm, and the exact same fueling...

... then what do you suppose drive pressure is going to do?

seriously, before making comments about something you haven't tested, you really should test it. You really have no clue whats happening with drive pressure when you close the vanes :wtf1:, I thought you were testing things like heat and efficiency?

[killerbee]

Larry, do you think that any of the vane tables control vane position for boost control? They don't. Closed loop boost control, with the use of a boost controller, unexploded in EFILive, is used to vary vane position to meet DESIRED or COMMANDED boost.

IOW, boost is controlled with logic we have no access to, embedded in the ECM, part of the 1024 we don't see in tables. The vane tables mislead people into thinking they can be used to influence boost, when in reality, the only useful table is max vane, and that only permits the production of higher boost numbers, albeit at considerable cost to drive pressure, naturally. But if we are talking about relatively low boost numbers, like 20 psi stock tuning, then raising max vane has no effect.

Target vane, just gives a vane position "rest" place when there is no disparity between set point (desired) boost and present boost. It is, more or less, a worthless table to the tuner. IMO

[jpgmtech]

Target vane postition is accessed on a delta TP event to provide an initial reference for the vanes. After a certain predefined delay to allow the turbo to respond, the ECM starts modulating the vanes to produce the boost requested in the Desired Boost tables.

Changing turbo vane target primarily changes the responsiveness of the turbo. It has no effect on final vane position once fuel rate is stable.

In my experience, the stock max vane tables will allow as much or more boost than I am comfortable with the stock turbo. Just set the desired boost table to the maximum value, and the ECM will always run the vanes up to the maximum limit.

This is not what KB did: he set Desired Boost to 20psi and ran the max table at 100%... even though the max table was set high, the ECM will only modulate the vanes to get 20psi, usually 30-40% at a lower altitude. The ECM has no reason to go for higher vane position, therefore drive pressure remains stable.