Understanding Boost Control

[forcefed86]

On The Boost Control Option Screen....

I'm trying to get the "Boost timed from launch" working properly. What parameter is the MS using to know when I have launched? Launch in? I'm using the launch in for my 2-step so I know thats working.

I've confirmed with no pressure to the top of my WG I get 9lbs of boost. (wg spring pressure) With my Boost Control Solenoid open 100% I'm getting around 20lbs of boost.

What I'd like to do is setup the "Boost Timed from launch" to start me out at 9lbs and ramp up to 20lbs by 4 seconds. Yet I'm having all kinds of difficulty doing this.

What should the "Boost Control Target Table" be set at? 240KPA? (20psi). (closed loop mode) Or should I run open loop mode and just do DC? If so what should the Boost Control duty Cycle table read? 100% Dc?

Here is whats happening on my data log... and my MSQ.

[Matt Cramer]

Yes, it goes from when the launch control switch is released.

I'd set it for closed loop and target 20 psi. Then ramp the boost from 45% to 100% over 4 seconds.

[forcefed86]

Thanks Matt, I have tried what you suggest with no luck. I am logging my turbo back pressure which is what I am also using to control boost. I have roughly 40psi drive pressure at 20lbs of boost going to the top WG port. So I know I have plenty of pressure. System is air tight. Simply having the solenoid on/off nets me 9 or 20lbs so I assume the inverted/normal settings are fine and the system is working. The MAC valve pulses steady in TEST. So I believe my problem is still in the settings.

I believe it has to do with the boost control target table? Does the BC system ignore the “target table”? If I have 100KPA or 250KPA in this table will it matter? THe target table looks like it goes off RPM and TPS which is odd. I don't wish to control boost based on RPM. Just on a ramp in time and or VSS.

What should my target table be set at to accomplish proper “boost ramping”? It seems like BC is ignoring the ramp feature and just reading straight off the target table. I also have VSS hooked up and tried to setup boost by speed with the same luck. It seems to ignore the commanded “ramp in” and just goes off the target tables.

Thanks again!

[Matt Cramer]

The tune file you posted is using boost by speed and not the ramped in target time. Can you post a MSQ and data log demonstrating the problem you're having with the ramp-in function?

[forcefed86]

Will do. I was going back and forth at the track to try and get one or the other to work. Guess I ended with VSS. I’ll U/L the timed ramp log this evening.

Question is still the same. Since the duty table or closed loop KPA table is based on RPM/TPS, what should I have in the cells? As mentioned I want to ramp in boost over 4 seconds. Will the ramp in input ignore the boost target table?

[Matt Cramer]

You'll need it set to your target boost level. The ramp in is a multiplier that scales the boost target (in closed loop) or duty cycle (in open loop).

[forcefed86]

You'll need it set to your target boost level. The ramp in is a multiplier that scales the boost target (in closed loop) or duty cycle (in open loop).

So If the MAC valve 100% open nets me around 20psi (which what I want) I set that to 100% across the entire RPM range above the TPS I want it active. (or 250ish KPA).

[forcefed86]

So I found the 1/16 OD copper tubing I was using is some sort of 02 capillary tubing. The ID is crazy small. It was sold as mechanical gauge tubing on ebay. I believe this is what was causing the control issues. I hooked the line up inline with my mechanical oil pressure gauge and the response was extremely lazy needle would lag behind for a good 4-5 seconds. Ordered some 1/4 copper ID tubing to try.

[forcefed86]

Got rid of the exhaust drive pressure rig and set the BC up like so. Still having issues.



With the closed loop BC I have the solenoid set to normal (vs inverted) This seems like it allowed 12lbs initially and as the VSS went up, the boost went down to 8-9psi.

So I inverted the signal with no other changes and I saw 23+psi pretty quickly with zero duty on the WG solenoid.

So I'm assuming that the "normal" setting is correct, yet why am I loosing boost as the VSS rises? how can I get boost to progressively rise with VSS1?

Attached are the two logs. And 2 MSQ files

Thanks

[forcefed86]

INVERTED msq.

[nathaninwa]

That plumbing is not correct. Source pressure from the turbo T's off to the bottom of the gate and the inlet of the valve, the middle one is vented to atmosphere and the other side Gos to the top as shown

Here's a diagram off diy's site. http://www.diyautotune.com/catalog/ebc- ... p-285.html

[forcefed86]

Appreciate the reply, but it is plumbed properly for my application.

[nathaninwa]

Can you link to that style of plumbing? Im running normal with a 3 port valve and have ran boost versus vss in a rising rate like that with good luck

[forcefed86]

Can you link to that style of plumbing? Im running normal with a 3 port valve and have ran boost versus vss in a rising rate like that with good luck

You will be able to run more boost the way I have it hooked up because it stops applying pressure to the bottom port. It allows the lowest "spring pressure" setting as well as higher pressure than you could get with it the way you have it hooked up. Either way should work. It's just the control strategy in the MS that isn't setup properly for the way I'm using it.

[nathaninwa]

I think I see it now after some googling. That way provides max boost pressure and I think is relying on back pressure in the header to open the valve and providing duty cycle to the top only makes the pressure differential much higher. With the bottom to the vent side of the valve it really doesn't see anything , well I guess it would in small duty amounts the same as the top does. Interesting


In my setup, running an 8psi base spring, I'm able to run 31 psi in the low 80% range and running a 16psi base spring it only took about 55% to get 32psi

[forcefed86]

I need 8-9lbs for street driving and 25ish for the track. With the 8lb springs I'd see 18lbs or so and creep to 20 with it plumbed the standard way.

[forcefed86]

Still can't get this to work properly. Any help appreciated.

I can turn off the boost buy speed and set my DC manually to 0 and get 8ish lbs. 34 nets me 14.5lbs 45 gets me 17.5ish. So the DC and solenoid are working. When I make a pull with the boost by speed turned "on" the DC does nothing. I have it set to taper up to 35dc by 60mph. Then from 60 I continue to ramp up to 50DC. I just made a pull to 112mph and the DC sits at 0 on the datalog. Boost is at minimum the entire pull.

[nathaninwa]

Which firmware are you on? Pre 1.4.1 had a bug that was off by a factor of 10

[forcefed86]

Using the newest Tunerstudio update and the latest MS3X software. No idea what number it is without looking though. Also noted today that closed loop VSS BC does attempt to regulate boost a least a little, open loop does nothing. I'll play with closed loop a little this weekend.

[nathaninwa]

You will need the newest beta, 1.4.1 for it to be accurate. Otherwise the gas mph would need to be 3 for 30mph and so on