Hi

I have a JDM VII, the restrictor you mention is 1.1 mm ID on my car, can't tell you the length.

I ahve experimented with adjusting the internal diamiter of this pill rather than the one near the actuator. I have found on my cay that it is much easier to adjust boost with this restrictor. I've gone upto 1.2 mm. Will try other sizes when I get the chance.

MN

 

I am unable to log boost so I was curious to know what the calculated load is for 20 psi? Thanks in advance.

 

Ignorance is bliss.

 

This like saying disconnect the water temp, because my autometer gauge does a better job than the H or C I get on the dash readout.

hehe

 

This thread is really informative - thanks guys! Let me try to summarize a little, and then add a question for you:

Stock Boost Control Setup
The values in the Boost Desired Engine Load table determine what load the engine should be at for a given rpm. Since load is directly linked to boost, that's your target boost values. If the actual load is not equal to the desired load, the values in the Turbo Boost Error Correction table tell the ECU how hard to adjust the WDC to achieve the desired value (big value = sharper adjustment). The ECU than adjust the WDC unless one of the following is true: (1) the max WDC value is reached, as specified in Max Wastegate Duty table, or (2) the max boost limit is exceeded (as specified in Boost Limit Table). In addition if the limit is exceeded for a time duration longer than what is set in the Boost Cut Delay Timer the ECU cuts the fuel. In this setup, the max WDC table is 100% across the board.

Higher than Stock Boost Setup
Given how the stock system works (if I got that part right), you'd think that simply raising the values in the Boost Desired Engine Load table would result in higher boost. However, that doesn't work because no matter how the ECU adjust the WDC, the restrictor in the boost line does not allow it to bleed air at the needed rate. So you need to change the restrictor pill before the ECU can assert any control at higher boost levels.

My question is this: why do people advocate setting the desired load to a very high value (higher than actually desired?), and then clipping the response by limiting the max WDC? From the original setup it looks like the max WDC table is more of a safety feature than a feature meant to shape the boost response. Has somebody had success with changing the pill, leaving the max WDC at 100% across the board, and then altering the desired boost and error correction tables to achieve the boost curve you want? Using the method of clipping response with the max WDC table obviously works, but it seems a bit like using the system in a way it wasn't designed for - so I was wondering if the "normal" approach is also an option.

 

I believe the Wastegate Duty value(s) in a sense are what controls the boost; zero out the error correction and you should see what i mean. With the error corrotion map zeroed out it should control the boost strictly off the values in the Wastegate Duty map, assuming you do not hit one of the boost limit values.

 

Ill answer..

I have tried this. With a modified pill, using like 50% WDC, I would get my normal pump gas boost (21-22lbs). I tried to raised the WDC to 100% and lower the load target and I could not control the boost.
I also tried to raise and lower the load target on a stock boost system and it didnt raise or lower boost.

 

hm ... thanks guys. Can't argue with success (or lack thereof), just seemed like it should work that way... tells you what I know

 

When you say this can you characterise the amount and type of boost spikes you were getting? I am curious how keeping any pill at all causes erratic behaviour when eliminating the BCS pill makes it a steady curve to be tuned? Maybe I have yet another freaky system that no one else does, but removing the pill and recurving the map lower was the easiest thing I have tuned. What I noticed with the BDL and WGDC maps is that a 10% change resulted in a 5-7% overall boost change more or less. If 159.4% was 26psi then dropping to 143.5 or 24.7 psi. I get some variance because of atmo conditions but more or less this formula has held during my testing. Right now its curved at 147.5 at peak torque which is getting me 25psi. This is roughly a 5%% drop (26 to 25 psi) in boost with a 7.5% change of map resolution. The WGDC map is curved similarly.

 

Are you boosting 25lbs without using a modified pill?? If so, are you using a MAP sensor (just checking)??. I havent seen a stock system that could go over 23lbswith out a modified pill (cept for the euro/JDM twin solenoid setup).

The part you bolded where i said i couldnt control boost, i was saying that with a modified pill, putting the Max WGD at 100% and trying to use the load target, couldnt get the boost to go down (it was boosting 27+ lbs). Using the Max WGD, I was able to lower the boost.

I was thinking a playing with the stock boost again and getting to the bottom of complete ECU controllored boost control.......

But to tell you the truth, Im liking my MBC, so we'll see.

 

Yes that is correct, I have no restrictor in the BCS line. I do have (but am not currently using) an add'l. bleed valve inline to the BCS to achieve over 25 psi when I want it. There might be a slight difference between the MR and a GSR BCS systems (restrictor pill size) as my car hit 23 stock, I dont know for sure. I checked this psi against 3 different gauges to make sure I was calibrated. The autometer that is in my car, one of my father's diesel gauges (Isspro), and a Defi with recall.

The pill that is in the wastegate line (there are 2 as I understand the system) is still stock, while the one nearest the BCS has been removed just to clarify. I also have done this to 2 of my friends cars (a IX GSR and a IX MR) with similar results.

JohnB

 

Before you start making statements, like your car boost 23lbs stock, you should go get a MAP sensor and REALLY log it. You might find out your "23lbs" is only 20-21lbs. All analog gauge are usually off.

There is nothing different between the MR and GSR boost systems.

 

When you tested this what values did you have in your error correction map?

 

I believe I zero'd it out when I tried using load target to change boost.

 

I use the max wastegate duty to set the overboost spike. A small overboost spike of about 1 PSI gives a nice response, then the closed loop control system catches it well after that, with a critically damped response.

You cannot raise the boost level if the max wastegate duty is inadequate.

You will get oscillation and horrible control if the max wastegate duty is too high.

Below is a MAP vs RPM datalog. This is a setup I emailed to a gentleman with a UK/JDM IX, the boost units are kPa. He uses a variety of gears and you can see each time he just slightly overshoots and then it stabilises. I edited up his boost desired engine load for the second attempt which is logged here because otherwise it was pulling it back after it hit full boost. Note the programmed taper for pump fuel, the first solenoid ran at 100% max, the second at 75% max, with the original restrictors in place.

http://john824.fotopic.net/p37954051.html