Has anyone been using these maps to control their boost? Does anyone know when anyone of the specific Max Wastegate Duty maps are used; is it based on load, or what gear your in? I have noticed that if I have the same settings from "Max Wastegate Duty #1" in "Max Wastegate Duty #2" that boost in 3rd gear is down a couple psi compared to 2nd gear. If I increase the values in "Max Wastegate Duty #2", and leave "Max Wastegate Duty #1" as is, I can get 3rd gear to hold the same amount of boost as 2nd. Although if I increase the the values in "Max Wastegate Duty #1" to the values that are in "Max Wastegate Duty #2" I will over boost in 2nd gear; but 3rd gear will still be at the same boost level. Am I the only one that is seeing this happen?

 

stock turbo?

 

yes, i have also removed the stock restrictor pill.

 

just use desired boost load tables for boost amount and curve. For the record, 159.4 equals about 25psi and 140 seems to be pretty consistent at 24.

 

Interesting observation heyzeus11. There does appear to be some gear judgement stuff in the ROM, but I haven't worked out how it uses it.

The boost load target is the value in whatever of the desired load sites it is accessing plus the boost control load offset. So 159.4+80 is 239.1 load target. The restrictor, actuator and duty combo will set the maximum it will hit, the load targets set what it aims for. So you may not achieve target if the restrictor/actuator/duty combo is insufficient. If you exceed target, the duty will be reduced to attempt to pull it to target using the turbo boost error correction table which is the difference between present load and target load.

Some have 60, 80 or 90 as boost control load offsets depending on model. But if you max out to 159.4, you need to increase this offset to get it aiming higher (unless you fudge it by zeroing the correction table but then you just run open loop boost).

 

JC thanks for the clarification. I misunderstood what the Boost load tables were actually doing. So if I wanted a target load of 300 in a given rpm, to get the ECU to make it happen I would have to increase the load offset accordingly?

 

That is my understanding, although personally I've not played with it much.

300 is race gas load and probably a bit more than 2 bar of boost.

 

thanks for helping to clear this up for me.

 

Yeah I know . I have run as high as 30psi at the track on C16 (horrible trip in comparison to last one) so I have been in the 300% load at least. I am wondering though how much it has to do with going to the load percentage anyway. Let me clarify. X amount of boost at Y amount of rpm could very well result in 300 or 320 independent of the load offset correct? This is more what the car is trying to reach on its own for "optimum" performance?

 

Not quite sure I follow.

Load target = boost control load offset + boost desired engine load

The absolute manifold pressure in KPa may well be very similar to the load in the midrange, but really the target based system is targets of airflow/rev.

It is a closed loop system that ramps the solenoid duty cycle up or down at rates set by the turbo boost error correction map - the input to this is either actual load - boost desired engine load or actual load/boost desired engine load, I will try to work out which from disassembly at some point!

When I set very high duty cycles on a 3 port solenoid but had low boost desired engine loads I had a massive overboost which the ECU then pulled back. It pulled it so hard that it oscillated, and another time went over my 285 fuel cut as it crept over 30 PSI.

 

Sorry John, I have a tendency to sometimes not speak english when I am talking about cars. You however did a good job of explaining what I was asking, independent of my communication error.

 

Yes it is.

With 108-109 of duty (using the duty map value + the max correction map value) without the stock restrictor pill you should go up to 21-22 Psi at max tapering to 20 psi at 6000. Talking about an evo 8 2003-2004 using the 9.8T + a 3" exhaust + an air filter panel.

So if you use for example in the duty map = 100
In your correction map : -20 = +8 of duty.

Total is 108.

If your target load is > +20 of your curent motor load.
With this value of duty, you should reach a boost 22 Psi 3500 RPM tapering to 20-20.5 psi at 6000.

But it's highly depend of your WG actuator settings. So you really need a gauge to check the boost.



Arma.

 

There's no gear position sensor that I can find in the FSM, so I'm thinking that it keys off of engine load. Or perhaps it can figure out what gear its in by looking at rpm vs vehicle speed.

 

That is my understanding as well mrfred.

Arma, I think that the maximum duty is actually 100 and that the adjustment from the map is actually a ramp rate up or down per interval. I will confirm more when I've done more disassembly of the ROM.

 

No the maximum duty is 127.5 by memory.

And on our euro evo 8 & 9 we have in our correction duty map a max correction of
+27.5.

Hope it ll help.

Evo 8 & 9 EURO turbo error correction :
-20%= +27.5 of duty
-17.5= +27.5 of duty
-15 = +22.5
-12.5= +18
-10 = +14
-7.5 = +10
-5 = +6
-2.5 = +3
0.0 = 0
2.5 = -2.5
5 = -5
7.5 = -7
10 = -8.5
12.5 = -10
15 = -10
17.5 = -10
19.8 = -10

I dont recommend to use this boost correction map. Too much chaotic. Boost is very instable cause duty correction is too high.

Arma.