i havn't read it all - but:

Boost Control Load Offset = Base adder for the BDEL maps.

So lets say your BDEL map says 160%, and your BCLO = 100% THEN your target load = 260%

 

okay I see what your saying, so the boost control load offset, is not a starting duty cycle as such, but a blank value that is the base adder. Okay I will amend my "Essay" and ask for more critiques

 

Sorry for bringing this thread back again but having read through everything, I just want to clarify how I beleive it is working. If I am wrong please feel free to correct me.

Stock System and fundamental basics

The stock system works by running two restrictors, one between the turbo pressure source and the T-Piece which then feeds pressure to both the turbo wastegate and the bleeder valve solenoid. The Solenoid also has the second restrictor on the output side between the solenoid and the air cleaner inlet pipe.

The system works via the first restrictor "Restricting" the pressure to the system. What pressure is fed through, is then bled off via the factory controlled solenoid. Understanding that the wastegate once it reaches a a set pressure level, will start to open up and bleed boost off.

Now the second restrictor on the solenoid valves works opposite to the restrictor in the T-Piece. Its purpose is to restrict the amount of air being bled from the wastegate actuator. This increases the amount of pressure within the vacuem lines and opens the actuator sooner.

Removal of secondary restrictor on Solenoid

By removing the restrictor on the output side of the solenoid, this will increase boost slightly because the solenoid now can vent a greater volume of pressure from the vacuem lines. This reduces the pressure inside the vacuem lines, and means the wastegate actuator remains closed for longer until it reaches the set pressure to start bleeding off again. Due to the fact that this restrictor is very small, you will only acheive a 2 - 3 psi change in boost levels.

The Factory ECU Boost Software Setup

First thing to understand, is that the factory ecu / software as we are interpreting is reading in absoloute kpa. This means on the tuning maps, 0 - 100 is under vacuem, and 100 - 300 is our boost levels.

Now from my understanding we have three maps on the Factory ECU Boost control setup.

Boost Limit Map - which reads in total overall load in absoloute KPA

Boost Control Load Offset - this is the base adder to the boost desired engine load.

Boost Desired Engine Load - This is the desired boost level you are after, but with the addition of the Boost Control Load offset value.

Max Wastegate Duty Cycle - this refers to the duty cycle maximun value the ECU will use to cycle the bleed solenoid to control boost. At 100% this means the solenoid is fully open and bleeding off as much pressure as it can.

Turbo Boost Error Correction - this is the main map that seems to do everything. This from what I understand, looks at what the engine / boost load is, and if it is under the desired engine load, adjusts as a plus or minus to try and alter the boost level. This is where it can get confusing, as this value is added to the sum of the Boost Desired engine Load and Boost Control Load Offset. So as a mathematical Formulae it reads

Corrected Boost Level = (Boost Control Load Offset + Boost Desired Engine Load) +/- Turbo Boost Error Correction

Physical Modifications via the Boost Restrictor Pills

To clarify the first mod, as discussed above, removal of the secondary restrictor pill after the wastegate solenoid. This allows the solenoid to bleed off a greater volume of pressure and increase the boost level. The removal of this pill, with modifications of the primary restricotr, can induce larger boost spikes which may / may not be correctable via the software on the ECU. It appears that keeping this restrictor is not a bad idea as the majority of gains will come from modifying hte primary restrictor.

The secondary pill, as described above, its purpose is to "Restrict" the supply of pressure to the rest of the system. Essentially, removing this "Pill" and replacing with a new one with a smaller internal diameter, will mean that a greater pressure level is required before the turbo wastegate actuator can be activated. Depending upon the size of this replacement pill, you may or may not need to alter the software settings in the ECU. I would guess only marginally smaller sizes would allow boost levels to go from stockish 17 / 18 psi up to 21 - 22 psi without boost spikes or alterations. Going several sizes smaller, will definitly require alterations to the software settings.

Software alterations for large changes in the boost restrictor pill

Assuming say you have gone three sizes smaller on the boost pill and are aiming in excess of 24 psi boost levels. You would primarly need to first set the max wastegate duty cycle down to a starting values of around say, 30% and the correction factors on the turbo boost error correction to zero. You would also set the boost control load offset to aroundto the 159. Adjust the load offset value to the point where the boost level reaches the level you want to say 25 psi and then its a combination of fine tuning with the boost desired enigne load etc.. Then keep adjusting the wastegate duty cycle until the boost level level is fairly close to what you want. Finally once this is done, then adjust the turbo boost error correction maps to keep the boost level flat and stable.

Someone commented earlier that in the turbo boost error correction maps that the first four points referred to lower gears, and the last four values referred to higher gear levels. I think this is more a function of engine load where in lower gears, it can move through the rpm range faster, where in the higher gears, the vehicle moves through the rpm range slower giving the ecu more time to control the boost level via this map.

This has ended up coming through as more of an essay, but I guess its the way I think. I would welcome any comments on this, especially from long time tuners and players of EVO.

 

dude...

just edit your existing one hehehe

 

I didn't want to confuse people reading something with people commenting afterwards but I will do that in the future

Now to ask the next question once I have got the theoretical understanding working now.
I realise that data logging the waste gate duty cycle is the key to understanding this, to date what is the most boost that most people see with the factory pills in place, after software adjustments? Or is it pretty much necessary to alter the boost pills first and then do corrections with the software because the wastegate duty cycle is pretty much running 100% all the time?

 

It's all in load, not kpa.


Boost Control Load Offset has nothing to do with duty cycle and everything to do with target load for the error correction.

Boost Control Load Offset + Boost Desired Engine Load = Target Load.

Example:

BCLO = 100
BDEL = 150 @4000 rpm

Target load at 4000 rpm = 250

Boost Desired Engine Load is also not in kpa, but in load, refer to above for its relationship with Boost Control Load Offset

Turbo Boost Error Correction works by adding or subtracting wastegate duty cycle percentage above or below the *base* wastegate duty cycle depending on how above or below the actual load is from the target load.

Example, if you have 2 in the -3 part of the TBEC table, then if the car ever sees -3 off the target load, it will add 2% wastegate duty cycle to try and bring it back up to target load.

 

What you are using into the boost cut load table?
Currently I have 235;235;240;245;250;255;255;255;255 into this table.

 

I just did this mod to a friend's car and I'm pretty excited about how much easier this was than my GM 3-port to dial in. I also left the factory restrictor in and observed almost no spike at all. It spools to 223 load and drops to 220 and then bobbles around from there.

 

Really? To me, the GM 3port was always easier to tune.

 

Can anyone tell me what the standard restrictor hole sizes are for for an Evo5?

 

The stocker with a #57 pill is like painting with a hand grenade compared to the 3 port. 10 percent with the stock solenoid is like 2-4 with the 3-port. It's (the GM piece) much more sensitive.

 

I'm not sure but it's definitely a LOT bigger than .4 MM (.015 inch) which was suggested earlier in this thread. I can only assume he tried measuring with a vernier caliper.

 

I am running 23psi and tappering to 20, with stock pills in place, basically when you add an intake and TBE you would ge an increase in boost without doing any mods to the tables. I changed a few things to get to this level of boost.

 

That what i said? He said the stocker was easier to tune then the GM. I said i felt the GM was easier. Seems like you also think the Gm is easier, based on your hand grenade comment.

Also, just so you know I have tested all the pills, as I made the thread.

 

I think he meant that tuning with broad brush strokes is easier than fine brush strokes.

It works, but it won't make a masterpiece.