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Old 10-30-2007, 04:37 AM   #1
Broxma
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Default The Tuning Boost Targets Thread

Again a disclaimer – I am not a Tuner, just a guy with a lot of time. This post describes how I tune boost control and nothing more. This post is in response to the myriad of questions regarding overboost, underboost or GM/Prodrive/Perrin EBCS tuning related questions. There are a few people who believe what I say about tuning, but none of them would call me a tuner either. The images of certain tables are taken from Enginuity.


Disclaimer two – Your car has a value reported by the ECU I like to call “The Happy Value”. Classically known as the IAM( Initial Advance Multiplier). This number is a value that generally goes up when the car is not experiencing knock, provided the right conditions are met, and will drop if knock is detected. Logging this Value is a must at all times when tuning your car. For 16 bit ECU’s, the ideal value is 16. For 32 Bit ECU’s, the ideal value is 1.000. If your logs reflect a drop in this value, there is a problem with your map or the conditions you have placed upon it. These values MUST BE CORRECTED before proceeding with any modification. The information below does not address corrective action for dropping IAM’s due to timing or fuel related issues. If you are inexperienced with tuning and cannot correct knock related issues or are using an OTS map with no support and experience dropping IAM’s, your best bet is to reflash the stock map until you can have your map tuned by a professional.

On to the show…

First off let’s define what is going on with the boost control system in the most basic terms.

The ECU has a “Boost Target” map. This map may be under different names for different model years and models but it will look the same. This map sets maximum boost levels based on Throttle and RPM.
The ECU also contains a map called “Max Wastegate Duty (MT/AT)”. Some cars have several tables associated with this map; however for the 02-03 WRX there is only one which is applicable. This map sets Wastegate Duty Cycles (WGDC) also based on Throttle position and RPM.
There are two other maps called “Turbo Dynamics Burst” (TDB) and “Turbo Dynamics Continuous” (TDC). These maps add or subtract WGDC% dependant on the amount of boost error the ECU detects.
The WG actuator itself is not a digital device; it is not on/off. The actuator will open the WG flapper door a little or a lot depending on the WGDC and the pressure it sees.

So if we relate all these maps we can surmise that we set a Boost target, and then adjust the WGDC to achieve the target. Here is where the fun begins.

This is the stock 02 WRX Boost map.





It runs max boost of 13.61 PSI at >76% Throttle from 2380-4800 RPM then tapers off. Notice the drop to 6.65 at 6800 RPM. For throttle or RPM positions between the column and row values, it interpolates a number between the two, i.e. 6000 RPM at 100% throttle would be between 11.91 and 6.65 PSI.

This is the stock 02 WRX WGDC Map.





As you can see, the WGDC is almost 100% at low RPM across the board then tapers off again. Notice the 0.00 WGDC at 6800 RPM and how it corresponds with the 6.65 PSI on the boost map. Basically, at this RPM, the car is running WG pressure.

This is the stock 02 WRX Turbo Dynamics Continuous table.



In this map, negative values correspond to overboost and positive are underboost. Huh? You say. Well the ECU bases the boost error on the target map. So when you are under target boost, the ECU boost error reading will show the calculated PSI under that target, i.e. target is 16, current is 14, error is 2. On the opposite end, if you shot over, it will return the negative value.

I came to a fork in the road with two paths….

The Factory Boost Control Solenoid (FBCS) controls boost by bleeding pressure away from the WG actuator back into the intake. With this pressure being bled away, the WG will remain closed until the WGDC drops low enough for the WG to see pressure then it will open. The duty cycle is a ratio of the percentage of the cycle that the FBCS is bleeding this pressure. So a WGDC of 90% would have 90% bleed/10% to the WG. I have not confirmed the Cycles per Second but I believe it is around 10hz.

The two crude images below show the possible paths for pressure with the FBCS.



In this position, the FBCS is energized and the internal plunger has been pulled back by the electricity running through the solenoid. The WG actuator actually has some boost at it at all times in this configuration because the FBCS cannot bleed enough pressure away, hence the very high WGDC using a bleed type system.



Here we see that the FBCS is no longer energized and not allowing any pressure back to the intake. The pressure is then sent to the WG actuator, which opens the WG flapper
door.

When people speak about adjusting the WG arm, they usually mean shortening the arm to allow more overhead of the WGDC. By shortening the arm, the actuator will have to push harder before it opens the flapper door. Since as I stated before, the actuator is not digital, the shorter arm will increase the load on the actuator, or possibly put it in the proper position that the factory doesn’t in the first place. The point of this is that by shortening the arm, you will be able to use less WGDC to achieve target boost in most cases.

A 3 Port (GM/Perrin/Prodrive) works by blocking or “interrupting” the flow of pressure to the WG.

The two crude images below show the possible pressure paths using an interrupt style solenoid.



As you can see, the solenoid just blocks the boost from reaching the WG altogether. We also have removed the “T” in the line and the restrictor pill. This diagram doesn’t take into account actual connections obviously, just the principle of the design.



With no power to the solenoid, the unit will open up allowing pressure to go to the WG and actuate the flapper door. The third port on these solenoids is used for allowing extra air out of the system and is also used in external WG setups. The path of pressure is much more direct in this setup allowing for a much lower WGDC. There is still some latency between the opening and closing of the solenoid and it is still cycling at the same frequency, whatever that is.

What to do, what to do….

So how do we tune the FBCS or a 3 port solenoid to achieve target boost? We start off safe.

First, chances are you won’t be tuning from a stock map. You will have gotten a base map from someone and your boost error will be too high or low depending on the WGDC of the map.

Second, you need to log Max WGDC and Boost Error in addition to the normal values, using Enginuity or whatever program you use, so you can review the logs and see exactly where the targets are wrong. I prefer to do WOT pulls in second and third gear from 2000 RPM to redline, traffic permitting. This is not an endorsement to speed, so if you can do this at a track or a dyno, even better.

If you are not hitting target boost at WOT, raise the WGDC by 5% in the 100% throttle column. Be aware though that 5% of 20 is only 1, while 5% of 60 is 3. So as the WGDC% increases cut back on the % you raise it by. Enginuity has a way to raise value by % using the Multiply (Mul) button as show below.



I want to multiply the entire 100% Throttle column by 5%, so I put 1.05 in the input box, select all the values in the column and hit “Mul. I end up with this…



All values have gone up by 5%

You can continue to do this until your target boost is achieved for WOT. I find it best to tune with a passenger for one reason. They can watch the throttle % and tell me when to stop, which is helpful when adjusting WGDC to achieve target boost for partial throttle. Again, adjust the WGDC at the throttle point according to RPM. If you are overshooting your target at certain RPM’s, drop the WGDC for that RPM at the respective Throttle position. In an overboosting situation, it is best to make a large initial drop to the WGDC then bring it slowly back up, rather than try and tune the WGDC down.

The Up’s and Down’s…

Let’s say that you flash a map that has a max target boost of 16, you hit the road, start logging, and hit the throttle. The boost gauge quickly jumps to 21 then back down to 12 then back up to 20. This is most likely one of two things or a combination of both.

One, too much Initial WGDC and/or two, the TDC values are too broad. The TDC table is used when the ECU detects steady throttle position and the boost error is too large. There is another table which dictates what value the ECU will begin to check for boost error, but I have yet to find any reason to adjust that table.

The TDB table is used for quick response during fast transition of the throttle. If going from 25% to 100% throttle, this map will only be used temporarily, until the throttle position becomes constant and then the TDC map will be used.

When installing and tuning a 3 Port solenoid, modifying the TDC map is a must. The base percentages are way too high and will lead to serious boost oscillations at WOT. A good rule of thumb is cut them in half, do a logged run, and continue to adjust. Bear in mind the negative side when adjusting. You cannot simply multiply this number as the percentage will actually increase.



This is an adjusted TDC table I used for a 3 Port solenoid. As you can see, the numbers are much smaller than the stock table, because the overall WGDC with the 3 Port is lower. With a lower base WGDC 3 Port map, smaller changes to TDC will affect the combined WGDC the same as with the stock system. Compare this table to the stock table posted at the beginning and you’ll see what I mean.

So in short, you lower, then incrementally raise your WGDC to achieve your target boost. Sounds simple. For an average Joe, normal intelligence, you can probably figure this one out. The best bet is always to lower the WGDC map to a point where no target is achieved, and then adjust up until you hit your WOT target, then begin to adjust for partial throttle the same way. I prefer to tune this way because it alleviates the chance that my initial setting will overboost into catastrophic failure.

You will notice with a low WGDC that the car simply will not hit the target. You’ll have a target boost of 16 with 56% WGDC at WOT and the max boost will be 11. Adding 5 or 10% additional WGDC to the 100% column will increase it by some amount, say 1.5 PSI. This is just an example as there is no direct formula for tuning boost. The fact that there is no formula, and that WGDC percentages will change from vehicle to vehicle is why we have to adjust the WGDC maps. Maps you might download from around the internet will be tuned for different conditions and different modifications, so the WGDC tables could lead to boost error regardless of you having the same “required” modifications. The stock map works only because every car comes from the factory exactly the same, in theory, so the exact same settings will work on identical cars. However, modifications, altitude, temperature etc. all play a role in the ECU calculations and the function of the boost control system. So being able to tune for changes to the boost table is imperative to getting the proper performance from the vehicle.

Disclaimer Three – Modifying the boost table, WGDC and associated maps could lead to catastrophic failure of your car. The above information is only to be used as background information regarding the boost control system and the properties of it. At no time should you adjust any value in the ECU unless you are certain that the adjustments will not adversely affect the condition or performance of your vehicle. I take no responsibility for any adverse effects to any vehicle modified based on the information above.


/Brox
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Old 10-30-2007, 08:36 AM   #2
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Nice write up, you should post it over at enginuity if you haven't already.
IMO tuning boost control is probably the best first step in tuning for people new to OpenSource, it is how I started learning as well.
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Old 10-30-2007, 09:12 AM   #3
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Me too.

I've been thinking about scaling down the negative side of the TD continuous because when there's a positive boost error the negative side will cause it to undershoot the target boost and make it tend to oscillate. The JDM 03 WRX continuous table is symetric around the zero error point.

Last edited by MasterKwan; 10-30-2007 at 09:18 AM.
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Old 10-30-2007, 03:30 PM   #4
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Lots of good information there.

I'd like to add a couple of things, because tuning boost is integrated with everything else.

Before I do any WOT boost tuning I take about 4 degrees out (numbers are lower) so you are not detonating. There's not much point in tuning the boost unless you are NOT detonating. Don't worry about EGT while tuning too much it will be higher, but you won't burn a valve with a few pulls.

In general I start by removing about 5% of the fuel from the top load sites (I also rescale the fuel map for the increased boost). In general the stock fuel map is very rich. Next I remove timing, say 4 degrees, or about -20%. What you do with the dynamic advance table is a matter philosphy (where the multiplier comes into play), suffice to say the stock route is not recommended.

Now you are ready to start tuning fuel. You need a wide band sensor that is calibrated. It should read 14.7 while cruising (you should have already sorted out your injector calibration and MAF calibration).

You can tune fuel to the stock boost settings and then work your way up boost. This is the conservative approach. You are mainly "tuning" the wastgate duty to increase boost. You can alter the turbo dynamics, but really, what's the point unless you reach target boost. The dynamics are really about how the solenoid responds or how it arrives at the target. For sure, the more "proportional" or "gain" you have, both positive and negative, the more aggressively the solenoid is pulsed to reach the target. The AFR that you tune to is a judgement call. The lower the AFR the less power you'll get up to about 12.5:1. If you are new to tuning, I'd shoot for 10-10.5:1 AFR.

So, let's say you get the fueling dialed in with a constant stock level of boost, say 13 psi, all the way to redline. Now you can raise the boost and tune the fuel again. Go up in 2 psi increments. On the stock turbo, you will hit the limit of the compressor. Boost will start to taper with the stock solenoid no matter what WG value you set. With a aftermarket solenoid you can bleed off more air and hold boost pressure longer, but at the expense of compressor efficiency. IMHO, don't bother trying to hold on to boost with a small turbo. Let it taper. You are not going to get any more power by holding the boost pressure, because the air is just a lot hotter. You can prove this by looking at your MAF readings--no more air is going in.

So how high do you tune the boost? When do you know when to stop? It's a very subjective but there are some clues.

1) If the boost is tapering despite increasing WG duty at high RPM, this is where I'd stop. You can get more peak boost, but then your car drives wierd because the mid range has so much more torque. So, when it tapers a couple of psi from 5500 RPM to redline. That's your max boost.

2) What if you have a big honker turbo and you can hold 30 psi of boost all the way to redline. How do you decide then? You can't run 30 psi on pump fuel. Then its a combination of boost, detonation, and timing (fueling can come into play as well, but I don't use fuel to suppress detonation above a certain AFR). The max boost you can run with a larger turbo is the boost pressure where the engine starts to detonate and the timing still allows EGTs of less than ~1700F. Then I'd lower the boost by 1 psi and take a degree or two off of the timing.

People who tune all the time develop a pretty good guess of where the car will end up. They can tune faster because they can take bigger steps and fewer ones. If you are just starting to tune your own car, go slowly, take small steps. Don't change values by more that a few percent----and keep an eye knock at all times.

PS
Freon has a great thread on tuning the turbo dynamics for an aftermarket solenoid. I can't remember if it's here or there (Enginuity). He did a lot of trial and error work to really figure out how changing values affects the boost response.

In general tuning goes fuel-->boost-->timing in that order. Except with large turbos that are capable of much more air flow than pump gas can handle, then there is often a boost-timing cycle that iterates until you reach the maximum boost with low enough EGTs.

Better to start with rich fueling, LOW AFR, and work your way up. Better to start with retarded timing, LOW values, and work your way up. Better to start with LOW boost and work your way up. See the trend here......be careful!!
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Old 10-30-2007, 04:14 PM   #5
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I was just trying to fix my boost spiking at stock boost... Your post is an interesting read. I'm not ready to "up boost" yet but, I'll be referring back to this post when I do. I was thinking about going up 1/2 PSI at a time. Maybe I'll do 1 psi instead.
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Old 10-30-2007, 05:54 PM   #6
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Bboy...Thanks for the reply. I personally didn't want to get into fuel and timing tuning really with this one mainly because I view that as something you really need to see rather than read about, but you hit the nail on the head with your post.

The original purpose of the first post was to give a bit of background for people seeing boost issues and for them to understand that they could probably fix it themselves if they took the time and worked in baby steps. As for fuel and timing tuning, that just isn't something I could convey electronically.

I basically assume, because I have to, that the fuel and timing maps for anyone wanting to fix boost issues are already working as intended and that there is no need to adjust them. My intention wasn't to have people crank up the boost targets and then fiddle with WGDC's and whatnot, but I know alot of people have issues with downloaded and purchased maps when they flash them and the WGDC's are too low to hit target boost.

If it helps one person or saves them some time or headache, then the time it took me to put it together was worth it.

/Brox
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Old 10-30-2007, 08:37 PM   #7
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THANK-YOU!...this really helps clear things up in my head, see my post here about not hitting target boost with osecu stage 1 map. I think I will try the 10% increase in the WGDC first.

Thx
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Old 10-30-2007, 10:09 PM   #8
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Good stuff. I'm loving seeing these informative posts around here.

I do really like your "step by step" breakdown of tuning boost. I'll note a couple things:

1) This breakdown is really geared to 16bit ECU's, the 32bit ECU's have additional tables which make tuning boost quite a bit easier.

2) When tuning both types of ECU's (and really any turbo), I would highly recommend that everyone keep the "boost target" values within range of what the turbo can hit at that RPM. I often see guys who get lazy and place very high boost targets in the low RPM cells. This leads to integral windup and hampers the ECU's ability to control boost.
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Old 10-30-2007, 11:21 PM   #9
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Yeah I only mention the 16bit/32bit ecu difference when I briefly touch on the IAM issue. I have tuned 32 bit cars before and the method is the same, just more maps but in the end there is not much difference. Only note is on the DBW versions you have max throttle of 80% instead of 100%.

The reason I make these informational posts is the same reason as you apparently. I like it when someone takes the time to put together something that I find interesting to read and gives me some insight on the topic. I may not be the person who should be making these posts but I am fairly thorough with my research before I post something. I'm not big into speculating or guessing. Like, I honestly don't know the frequency of the electrical signal to the BCS, and I was sure to point this out. I had read that the EcuTek solenoid is at 10 hz though, which is where I got the number.

Even if people just read it and never put it into practice, but are better informed, then it serves its purpose.

/Brox
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Old 10-31-2007, 01:10 PM   #10
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When logging the IAM in Enginuity there are two options "Raw ecu data" and "Multipler" I assume we want to log the ecu data value as it is at 16, the multipler is just the value that it can increase/decrease by correct?
Sorry for such a newbie question, I just want to be sure as my value of 16 has never changed which I take to be a good sign.
Thx
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Old 10-31-2007, 01:25 PM   #11
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Yeah. You log the Raw ECU value.

Your IAM will most likely drop at some point though regardless. Alot of times there will be a singularity in the timing map that causes knock and the IAM's will drop and correct themselves within the same pull.

The IAM is only one of many things you need to focus on though. I consider the IAM the Dummy Light of logging. I generally check my IAM's for the entire run first, because it is the first clue of something going wrong. A/F, timing, knock, etc. any of these could be problematic or out of range of what you want, but IAM may not reflect this.

/Brox
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Old 11-01-2007, 10:53 AM   #12
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I changed my TD continuous yesterday to match a 03 JDM MAP so, the table is symetric around the 0 boost error point. In my runs yesterday, I notice it gets to boost and stablizes around target boost much quicker now. With the USDM map. there were large negative corrections if you overshot target boost. This causes you to undershoot target boost when you have even a small boost spike. With the change, you may still undershoot some but, usually it's under 1/2 PSI where before it might be 3 PSI. I do seem to have some tip-in knock but, that's unrelated.
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Old 11-01-2007, 03:27 PM   #13
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I seem to have some tip in knock right now as well but really just a few counts every now and them. Nothing is being pulled because of it, but I may try and adjust it out.

Right now I'm dealing with dropping KC's at high RPM with no change in IAM or Advance. I pulled my WGDC back to drop max boost to see if it cleared up but it didn't so I think it's timing related.

I gotta start working on my website now so no more long info posts for a while.

/Brox
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Old 11-02-2007, 06:43 AM   #14
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great thread
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Old 11-12-2007, 10:33 PM   #15
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this is directly related to the problem i was having earlir today ! thanks for the "lightbulb" so to speak ! now to kill some boost spikes
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Old 11-13-2007, 06:11 AM   #16
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Quote:
Originally Posted by Toolz View Post
When logging the IAM in Enginuity there are two options "Raw ecu data" and "Multipler" I assume we want to log the ecu data value as it is at 16, the multipler is just the value that it can increase/decrease by correct?
Sorry for such a newbie question, I just want to be sure as my value of 16 has never changed which I take to be a good sign.
Thx
I am not sure if you are following the IAM fully. Both values represent the same thing. You need to realize how/why they effect timing and how you arrive at Total Timing. A value of 1.00 means you will use 100% of the KC as it is presented in your Advance table. A value of 16 means the same thing, in that you will be using the max values in the total timing equation. Whereas 8 or 0.5 means you will use half of the Advance value as it is in your table.

So, 16 = 1.00(where you end up when the engine is 'happy' over a predetermined amount of time) and 8 = 0.5(where you start after a flash or reset) SOme people find it easier to look at the '16' value because it was all that was available in the original logger def. files for 16 bit ECUs.

I disagree with the statement that the IAM will always drop at some point. I do agree, however, that even on a stock map you will see Negative Feedback Knock... this can be for a multitude of reasons...besides knock. You IAM should remain at 16 or 1.00 with a proper tune.

I also want to stress how different an ECU the 07 is. Many tuners do not realize that you cannot tune it in the same way you would previous model years. They are very different ROM images, with many more maps...for all aspects of the tune. For some of the Maps, it is not even clear how, why or when they come into play. We have a very good idea, but there is definitely much more we can and will learn.

Sorry for the long post, and good luck. With a little patience, and alot of reading, tuning can be a very rewarding aspect to car modification and ownership.
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Old 11-16-2007, 12:19 AM   #17
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So with the tune that was on my car, the Initial and Max WGDC values were pretty close. So to control the spikes, I decided to lower the Max WGDC by 5% at the rpm/throttle% sites that boost error was negative.

In doing that, the Max WGCD was now lower than the Initial in some spots. So for the same (roughly - as close as the table resolutin would allow) site in the Initial map I dropped the WGDC as well by 5%. Has anyone else experienced this ?


So as far as I understand it starts out (Initial WGDC) with a lower chance of hitting target boost, and will have a lower tendency to spike (lower Max WGDC). Will this adversly affect anything else ?

I haven't flashed the map yet, so if anyone has comments by all means share.
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Old 11-16-2007, 10:02 AM   #18
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Quote:
Originally Posted by JMS77 View Post
I am not sure if you are following the IAM fully. Both values represent the same thing. You need to realize how/why they effect timing and how you arrive at Total Timing. A value of 1.00 means you will use 100% of the KC as it is presented in your Advance table. A value of 16 means the same thing, in that you will be using the max values in the total timing equation. Whereas 8 or 0.5 means you will use half of the Advance value as it is in your table.
.
Interesting...I did not know this.
Thanks!
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Old 11-16-2007, 02:36 PM   #19
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I recommend that you guys log TD integral and TD proportional using enginuity's latest defs. It will shed some light on controlling boost.

You should never allow it to overboost significantly. On a stage 1 or stage 2 car, the overboost is usually around 0.5 psi. So, the shape of the TD integral negative beyond -0.5 psi theoretically should not be that significant. I mirror the TD integral positive.

Use WGDC initial plus the TD integral to control boost. Don't overboost.

Here's a 2005 LGT Stage 1 (bone stock hardware) that I tuned for a friend. Sealevel in Hawaii. The blip in WGDC at 2400 rpm is my fault. It didn't affect performance but I cleaned it up later. The different curves are for different gears. Spool is affected by the loading (gearing).

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Old 11-20-2007, 05:55 PM   #20
Phatron
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16bit starts at 8 and increases/decreases by 4 up to 16 (depending on your settings of course)

32bit starts at 0.5 (8/16) and increase/decrease by 0.25 up to 1 (16/16)

Code:
0/16 = 0.00 = 0%          Adv Table = 10*, you will get 0*
4/16 = 0.25 = 25%         Adv Table = 10*, you will get 2.5*
8/16  = 0.50 = 50%        Adv Table = 10*, you will get 5*
12/16 = 0.75 = 75%        Adv Table = 10*, you will get 7.5*
16/16 = 1.00 = 100%       Adv Table = 10*, you will get 10*
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Old 11-20-2007, 06:21 PM   #21
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Excellent post! Thanks for the insight. Not only did it broaden my understanding of how the various parts interact, I can actually use this info.
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Old 11-22-2007, 12:16 PM   #22
JMS77
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I have to say for the new guys to Enginuity/tuning, MickeyD2005 really knows this software and tuning. He, and his posts are a very good resource for tuning and Enginuity. Keep up the good work!

Anyway, another thing to note with boost tuning is that when you have Initial and Max WGDC Tables available to you, you need to understand their relationship. That way you can maximize your results with less flashing. You should set your Max WGDC table at the highest values you need to achieve boost at all TPS/RPM sites. The Initial WGDC Table is a valuable tool to start you out at various sites in the Map. Turbo Dynamics will work to balance the two(very simplified here )

WHat I mean by 'balance' the two is that you need enough variance in the two table to allow you to hit boost and minimal enough that at any point in any gear, you can achieve proper spool without over boosting. Now that your head is spinning, let me simplify it...

The stock 07 STi Initial is about 10 units(WG % points) lower than the Max table. That way the ECU can use Turbo Dynamics(Init/Prop) to manipulate the values enough to hit boost without over boosting, in any gear. So if you hit the gas...100% TPS at 3600 RPM it may see 36% WGDC, whereas if you hit 100% TPS from 2600RPM the WGDC when you reach 3600RPM may be 44%. This is a result of TD and the turbo...etc... you get the point.

So, I guess what I am saying is it is very important to understand these tables, and how they effect boost production. Equally important is KNOWING your TURBO/Wastegate combo, and it's efficency/spool characteristics. Don't ask a GT35 to hit 25PSI from 2000 RPM....It just won't happen!

Good Luck!
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Old 11-22-2007, 05:57 PM   #23
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Quote:
Originally Posted by JMS77 View Post
I have to say for the new guys to Enginuity/tuning, MickeyD2005 really knows this software and tuning. He, and his posts are a very good resource for tuning and Enginuity. Keep up the good work!
Yeah, I've been spying on various people's posts to figure this stuff out.

Quote:
Originally Posted by JMS77 View Post
Anyway, another thing to note with boost tuning is that when you have Initial and Max WGDC Tables available to you, you need to understand their relationship. That way you can maximize your results with less flashing. You should set your Max WGDC table at the highest values you need to achieve boost at all TPS/RPM sites. The Initial WGDC Table is a valuable tool to start you out at various sites in the Map. Turbo Dynamics will work to balance the two(very simplified here )
This is actually where I'm at now. Looking at the Airboy's spreadsheet, I'm seeing wierd things going on with boost and target boost using the base stage 2 map. The weather just turned cold here, so I need to redo all of my logs before messing with WGDC and init WGDC.

Quote:
Originally Posted by JMS77 View Post
So, I guess what I am saying is it is very important to understand these tables, and how they effect boost production. Equally important is KNOWING your TURBO/Wastegate combo, and it's efficency/spool characteristics. Don't ask a GT35 to hit 25PSI from 2000 RPM....It just won't happen!
Do you know of any resource that lists out turbos/setups and roughly what to expect from them as far as boost/rpm? I'm just curious. I guess I can keep slowly bumping up values with my td04 until I just can't reach the targets anymore (or any of the other dozens of warning bells tells me to stop). It would just be nice to know roughly what to expect. Maybe I got that info already with my stg2 base map.

I'm not ready to mess with fuel or timing yet, so this thread is perfect for where I'm at.

Thanks again,
-Mark
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Old 11-22-2007, 10:29 PM   #24
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Well, the best way to get the info for the turbos is to go to the manufacturer's site. They have various resources to guide you, and you could always call too. Good luck.

I would probably not push it past 17.5 PSI on the stock TD04, and taper down. I would be more than happy to help you if you get stuck.
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Old 11-23-2007, 12:24 AM   #25
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Another down and dirty way is simply to plot manifold relative pressure (boost) vs load on a graph. You should see a linear relationship between the two.

Up the boost until you get outside of this linear relationship (boost increase without a corresponding increase in load).
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