Tuning boost in the rom

[west_minist]

Hello there!

When setting the boost in the maps, do you also have to alter the the Boost limit map?

I am in the process of completing AVCS tuning with very good results.

I am looking now at increasing boost very slowly with heavy logging.

But I would like to know what other maps I will need to tune in relation to this.

I am already aware of the ign, ign correction, avcs, fuel maps.

There are 2 boost 3d maps. Do you have to set booth to be the same?
There are the Auto & manual ones.

[qoncept]

If you're raising boost targets higher than the limits, yes, you'll need to raise them. One boost limit is for a CEL and the other is for fuel cut.

I'm not sure what image youre looking at but a lot of the older ECU versions had a seperate table for AT and MT transmission cars. Make sure you're modifying the appropriate one.

[west_minist]

Ok. I haven't seen the cel one yet and the boost limit I am trying to understand now.

But right now, my changes are w/ in the boost limits - at least the maximum one.

Please find the file attached.

We also notice that STI maps states 15psi, but the car is running 18psi from the ecutek logs.

Could this be correct?

[crazymikie]

Boost is a closed-loop system. You set the boost targets to the values you would like to see the car achieve. These values then serve as a guideline to the ECU to tell it if the car is currently over/under boost. From there, you need to modify the wastegate duty maps to achieve the boost limits you set. If you set the wastegate duty too low, then you will not achieve your targets, whereas if you set it too high, you will get boost osciallations as the car tries to remove duty cycle to get back down to the target.

Then there are other maps that will affect how quickly the car will ramp up the wastegate duty cycle (turbo dynamics - burst or coarse). Based on how far you are from your programmed boost target, this map will control how aggressively the wastegate duty cycle will change.

Once you boost has come up to target (or more precisely you have hit your wastegate duty cycle target), the turbo dyanmics - proportional or fine map comes into play. If you go over or under boost from this point, this map controls how quickly the ECU will react and how much off target boost must get before the ECU will modify the wastegate duty cycle.

If that weren't enough, there are a bunch of compensation maps for boost and wastegate duty cycle that will alter your boost targets, depending on intake temp, barometric pressure, etc. So if you aren't seeing the values you programmed, this could be the cause.

Finally, other changes in the tune can affect boost as well. AVCS can change spool characteristics as well as the VE/compression of the motor, so that will affect boost. Also, different AFRs can affect boost as well. Leaning the car out during the spoolup period will add more heat to the exhaust gas, causing the turbo to spool faster.

Boost is really the hardest part to get right. After you get all of this correct for a WOT pull, then you get to check things like how boost reacts at mashing the throttle at 3000 rpm, 4000 rpm, going 1/2 throttle at 5000 rpm, a run through all of the gears, etc. There are always compromises to be made. My car will spike a few psi if I got WOT in 5th gear, but I never do that, so I prefer the boost response in the lower gears.

Hope that helps.

Mike

[west_minist]

Thanks mike.

I am aware of the afr leaning out and avcs effect on the spool time. Was really surprise to see it happening now, instead of reading other tuners write up.

I started looking @ the wg and notice that this would have to be set to affect the spool up time and boost reach.

Its a fine art in tuning and I will continue to learn.

Out of curiousity, the ecu states 15psi, car doing 18psi, but the ecu makes no attempt to reduce it to 15. The car has an exhaust setup. COuld this affect final boost?

[west_minist]

Hi Guys,

I think I found the problem.

I think the turbo is running @ max or there is too much back pressure.

But I have increase the wg and the percentages in the logging is the same as the stock map, but I must say that pressure logs are extended.

For instant, just into spooling, wg = 100%. The logs state 89%

I continue to find info stating that the turbo supports up to 400hp. We are not to far from that, but still a lot is left in this turbo.

Would the sti exhaust system hinder this?

From the post above, I guess we have reach our goal with the stock system, but looking @ that boost curve, we may be spool later, although 300rpm soon on your maps.

Please see below.

[west_minist]

Analysing the logs some more, going on the abs graph, I can see the wg need tuning to get the boost we want. I can see that effects before 4800rpm.