Turbo Dynamics, simply a PID control system

[caramall2]

Thanks much guys. I appreciate the info. Will try the "Bug" method, and now I know what those numbers mean ;-)

 

I'm a total newbie, but...I log in RR, but to tweak my maps when trying to tune, I like ST real maps (I did input an initial map in RR/ECU Flash so I could change things like "per cylinder timing"). The biggest beef I have with RR/ECU Flash is it seems you can't just "paste" in a row or array of values from a spreadsheet. I like to fiddle, use forumulas, highlight, input notes in Excel for the various tables in a map, then paste it into the tuning software. Helps me remember what and why I did something--probably just because I'm so new at it and everything is fuzzy.

[caramall2]

Need some clarification:

 

Establishing Open Loop Performance

 

- Steps 1-5: Do this at WOT?

- Step 6: Up WGDC low and high by 10. Just in the last column (80+ throttle)?

- Step 7: Go to 3? Do you mean go to 5, and interate (upping by 10) until you reach target max boost at some point in the WOT pulls?

 

Then you use all that WOT data to make a linear (or non-linear) curve and extrapolate; say for any given WGDC low cell, if you want boost “Y” then set the WGDC low value to “X”, correct? And you fill your whole WGDC low like that.

 

Thanks.

[Ridgeracer]

Once again...Could a Mod sticky this?? I could use this info for when I go EWG.

[bugblatterbeast]

Need some clarification:

 

Establishing Open Loop Performance

 

- Steps 1-5: Do this at WOT?

- Step 6: Up WGDC low and high by 10. Just in the last column (80+ throttle)?

- Step 7: Go to 3? Do you mean go to 5, and interate (upping by 10) until you reach target max boost at some point in the WOT pulls?

 

Then you use all that WOT data to make a linear (or non-linear) curve and extrapolate; say for any given WGDC low cell, if you want boost “Y” then set the WGDC low value to “X”, correct? And you fill your whole WGDC low like that.

 

Thanks.

 

yes, yes (for this step), either 3 or 5 will do as the P and I gains should still be zero.

 

there are some subtleties when tuning at part throttle but I left them out of the guide to avoid confusion.

 

how's the tuning going?

[caramall2]

Thanks for the feedback.

 

Humorously (and not so humorously) I heard some weird sounds while doing the pulls at the various WGDC...found the problem...header is cracked at the collector (the sound was the header stressing and cracking I'm pretty sure). Barely 1 year old...going back to OEM cast iron as I'm a little worn out trying to get the car on the road ;-0

 

So...down and out for a little while until I get things swapped out (ordering Grimmspeed's p&p version). I really need to get going as I have a big track weekend in about 4 weeks...getting down to the wire.

[caramall2]

My brain is a little mushy today...just want to make sure...

 

Delta = target - actual, correct? So that if actual boost is too high, you have a negative delta and the change in WGDC % is negative (WGDC reduced)?

 

Or, to put it another way, TD Course High is for when you are under boosting and need to increase WGDC, correct?

 

One other question...if that's the case, why are the positive TD % greater than the negative in stock map (e.g. seems to have greater correction ability over underboosting than over boosting)? Just curious.

[caramall2]

I posted this elsewhere but thought I'd stick it in here. (This thread really should be stickied). Some of you may have some tips or corrections as well.

 

-----------------------

 

So I was overboosting. My WGDCs seemed ok, I lowered TD integral some, but still was having problems. Then I realized the boost targets were just too high in the 2500 to 3000 range. The TDi would spin up so much that when the turbo finally really hit full boost, it would overshoot.

 

So, after doing all the pulls for various WGDC (Bugblatterbeast's method), I knew where and when, for each gear and RPM, the system could reach various boost levels. As a result, I lowered the target boost to a more reasonable level (though still slightly high to reasonably spin up the turbo), and now I'm not overboosting.

 

Using Bugblatterbeast's method helped me to really know what boosts can be attained at the various WGDC and in the various gears. This helped me to set low and high WGDCs, that I could confidently know would not cause excessive overboosting at any given point.

 

One note of caution--as part of Bug's method, when you do pulls at 70, 80, and 90 WGDC, you obviously have to stop early to prevent overboosting (remember, you've turned off all TD controls when doing these pulls)...e.g. as you do pulls in each gear (at least up through 3rd gear and partial 4th), you start at say 1900 RPMs, but then will have to let off quickly at around 3100 or so (especially at 80 and 90%)...you generally can't keep pulling all the way up. You really need a boost guage staring you in the face to do this (as I did)...you can't be looking over at a laptop or trying to check an AP. For the higher RPMs and higher WGDCs, you can tweak those/log those through other means (e.g. with the TD controls in operation, slowly increasing target boosts to see what you can attain (remember the goal is more air flow (MAF), not just more boost)).

[bugblatterbeast]

So, after doing all the pulls for various WGDC (Bugblatterbeast's method), I knew where and when, for each gear and RPM, the system could reach various boost levels. As a result, I lowered the target boost to a more reasonable level (though still slightly high to reasonably spin up the turbo), and now I'm not overboosting.

 

 

Another method to avoid large overboosts due to integrated error and still have fast spool up is to set proportional so the system is grossly underdamped when the boost error is large (and below SP). You still want a little less than critical damping when boost error is small. The boost control system will hold the integrator if WGDC initial + the proportional correction + integral is greater than WGDC max. I didn't put this in the original guide as it is easy to get wrong.

 

Also, when selecting boost targets, it helps to pick them such that a shift at redline results in the system targeting a pressure ratio and flow (post shift) that has the turbo spinning at the same speed (pre-shift). You will need the compressor maps and a bunch of experimentation to get the setup right. You will have pretty much no boost spiking post shift if you do this.

[LittleBlueGT]

Also, when selecting boost targets, it helps to pick them such that a shift at redline results in the system targeting a pressure ratio and flow (post shift) that has the turbo spinning at the same speed (pre-shift). You will need the compressor maps and a bunch of experimentation to get the setup right. You will have pretty much no boost spiking post shift if you do this.

 

I really wish I could see some logs from you showing me this.

 

Everyone else that has an AVO380 shows the same things I do, the WG actuator opens too little, and allows for easy overboosting in a transient situation.

 

ie, here is a screen shot from a 100F day last summer:

 

http://i248.photobucket.com/albums/gg194/littlebluegt/WGboostJun2608.jpg

 

It is WG boost only, the actuator is hooked up directly to the comp side of the turbo. The spike you see is what happens after a shift.

 

I tried two different WGs from ROSS, then I tried another WG (10psi) off of another member. I tried tapping the cold side of the TMIC too, no matter what I did I always get a spike after a shift. I was able to work around this with some creative td tables, but I cannot have an aggressive pro setting.

 

It gets worse when you start trying to control boost up from WG value. In fact if WGDC at 5000 rpm was 55%, then at 7000 I shifted, it would have to be at 40% or less to not overboost at 5000 rpm (post-shift). It was not uncommon for me to get a 2-3 psi spike, and that was with a pro setting set at about 5% max, and the int would hardly have wound up at all. (due to really creative settings on it)

[bugblatterbeast]

I really wish I could see some logs from you showing me this.

 

Everyone else that has an AVO380 shows the same things I do, the WG actuator opens too little, and allows for easy overboosting in a transient situation.

 

ie, here is a screen shot from a 100F day last summer:

 

http://i248.photobucket.com/albums/gg194/littlebluegt/WGboostJun2608.jpg

 

It is WG boost only, the actuator is hooked up directly to the comp side of the turbo. The spike you see is what happens after a shift.

 

I tried two different WGs from ROSS, then I tried another WG (10psi) off of another member. I tried tapping the cold side of the TMIC too, no matter what I did I always get a spike after a shift. I was able to work around this with some creative td tables, but I cannot have an aggressive pro setting.

 

It gets worse when you start trying to control boost up from WG value. In fact if WGDC at 5000 rpm was 55%, then at 7000 I shifted, it would have to be at 40% or less to not overboost at 5000 rpm (post-shift). It was not uncommon for me to get a 2-3 psi spike, and that was with a pro setting set at about 5% max, and the int would hardly have wound up at all. (due to really creative settings on it)

 

I'll see what I can dig up for you LBGT. I haven't really been logging or tuning lately so I might need to find some time to take a few pulls.

 

I suspect the reason you are getting spikes in the logs above is the relatively low boost target at the end point of the shift. What I think is happening is your turbo hasn't spun down enough to match the air flow and boost pressure target post-shift. My boost targets are selected such that the expected shaft speed before the shift and after the shift are almost the same. IIRC i'm set for ~22psi in the mid range and ~19 at 6500. I have a sharp drop to ~17 at 7000.

[LittleBlueGT]

I'll see what I can dig up for you LBGT. I haven't really been logging or tuning lately so I might need to find some time to take a few pulls.

 

I suspect the reason you are getting spikes in the logs above is the relatively low boost target at the end point of the shift. What I think is happening is your turbo hasn't spun down enough to match the air flow and boost pressure target post-shift. My boost targets are selected such that the expected shaft speed before the shift and after the shift are almost the same. IIRC i'm set for ~22psi in the mid range and ~19 at 6500. I have a sharp drop to ~17 at 7000.

 

I totally understand what you are saying, but can take 4 secs to do the shift (the turbo has slowed a lot by then) and it still does the same thing. I will have to see if it as severe.

 

In fact it will do it w/o a shift. I can just hold the rpm steady at 5000 rpm, then floor it, boost spike! But if I have already spooled the turbo at an earlier rpm the WGDC will be much higher, and still not spike at all.

[caramall2]

Interesting (good to see you back LtBlue). I thought I had fixed it but only slightly. I think I saw from an old map of yours you setting TDi high to pretty low value up high, and TDp fairly large up high, I assume in an effort to stop TDi from spinning up so much.

 

So I tried that...my TDi up high (large delta) is only about 2%, with my TDp being about 9 or 10%.

 

Anyway, I'm still getting:

 

a) a bit of over boost on a long 3rd or 4th gear run (e.g. it builds, overboosts, drops a bit more than I'd like (maybe need to minimize the TDi low a little), then levels out).

 

b) same problem as you when flooring it most anywhere from 3200 on up...it will spike a little, drop a little, then taper out.

 

With 0 WGDC I'm at about 14 psi max in 3rd gear (I think it was Rallitek saying they tuned their WRX using the AVO 380 with the actuator set to hold about 15 psi at 0 WGDC).

 

My 80%+ boost targets down low in 2800 or so are only about 2 psi over attainable in 3rd gear. I think my 40% throttle or so may be a little high or something, need to get my head around that.

 

I must say it's nice to have my car actually RUNNING for a change ;-) Though not happy with the tune yet, it sure is fun to squeeze on the throttle and take off (my other car is an older Protege...you don't exactly take off...). I also put on my Z1 tires and am very pleased (235/40/17). But I digress.