120 replies to this topic

[ARD - Lucky]

Tuning 101, the thread

The point of this thread is to bring to light information that will help you get the most from your tune, regardless where you get it. For this discussion we’ll be focusing on US market M4.3 models. I’ll have another thread up for M4.4 as it is a vastly different fuel system in respect to its considerable increase in map density and complexity.

Let’s start with the basics:
Fuel and timing tables/curves are predominately predicated on the supporting components of the vehicle. I.E. if the car has larger than stock injectors or a larger MAF the fuel tables must be tuned for this specifically, there is no real room for freehand tuning. It's essentially a function of math to hit the intended Air/Fuel target at any given load/RPM point. Ignition tables do have some room for differences tuner to tuner and this comes primarily from the 3 main maps that make up the base timing table. Things like WOT ignition timing, advance timing multiplier, part load timing, and the interaction of these 3 maps provides some room for tuners to vary how they control ignition timing. Remember when your algebra teacher said you’d need this later in life, well at least for me she was right.

So far as boost goes it’s all over the place and has more to do with each tuners particular take on how a boost map should be curved. In the following video you can see more about what I’m referring to. Boost map curves are wildly different and can be freehand tuned quite a bit more than fuel and timing maps. Point of clarity, of all three timing is king when it comes to power.

As far as this thread and the information in it goes, I want to be clear on this point, my intention is not to bad mouthing other tuners. My point is to simply bring forth information for the community to weigh, then make up your own minds on what best suites your driving style, environment, and particular vehicle setup.



Let’s dive in a little deeper:
Neither M4.3 or M4.4 have a boost pressure sensor, neither do they have a MAP sensor. M4.4 is equipped with a BARO sensor but its sole purpose is to measure the altitude the vehicle is at and help dial in the fuel adjustment alt variable. M4.3 does not have a BARO.
The ECU calculates engine load using the following sensor inputs MAF, TPS, RPM. Now, don’t muck up the waters and use the term volume when referring to MAF, the MAF measures air MASS not volume. This is important to understand for discussions around boost curves. Once this Load (Sometimes called LOD) variable is calculated the ECU can compare this value to the current BCS duty cycle on the boost map and extrapolate a boost value. Believe it or not both M4.3 and M4.4 have overboost maps but these maps are pretty small and don’t provide much resolution so the overboost map only acts when overboost is pretty significant. This overboost map is not to be confused with the internal load limiter also known as ‘fuel cut’ or the MAF flow limitation map.

Recall that the two axis of the boost map are RPM and throttle angle. An interesting note in M4.3 the ECU stops measuring throttle angle past 58 degrees. Why? Throttle angles past ~55 degrees have little impact on the actual amount of airflow entering the engine which is also why upper throttle angle boost curving is so challenging. As a tuner it’s where I spend most my time in the boost map making ARD Tunes more linear. In this way it makes for a much more driveable car. The Boost is less on/off and more gradual with respect to throttle movement.

Day by day:
As a driver what do I need to know about M4.3?
For starters M4.3 relies HEAVILY on base value. Values such as wastegate pretension, accurate sensor readings (i.e. MAF, TPS, O2) and good state of maintenance are CRITICAL for proper engine operation and boost development.
So does that mean that a TPS out of adjustment could affect my boost? Yes, it certainly can. However the primary two issues I find with folks who experience odd running or boost development after receiving a tune who had a stock ECU before come from ignition misfire and vacuum leaks. Components that operated fine under stock levels of performance will suddenly show their age as increased levels of performance/boost ask more from the components and they start to fail. Good stage 0 is my #1 recommendation when it comes to performance from these cars.

Why can’t I just crank up my wastegate and go by feel? You can however it will take a bit longer to really dial it in and doing it right is so much better. The ECU calculates the boost based on what the Load value is and overlays that by the BCS duty cycle. The ECU is programmed to expect the wastegate to open at a certain pressure and if this is off by even a few psi then you can end up with a car that will never fully boost or has boost overshoot you can’t control. I’ll have some further info later this week once I get measurements back and we can go over some basic math to understand why wastegate adjustment is so important and why tight sprung wastegates can be useful if selected correctly.

That’s enough for us all to chew on for now. Feedback and questions are always welcome!

[Zappo]

Well done.

[Jack8745]

very interesting. pin her up

[lizzord30]

Does changing the Sport to economy mode change the boost map?

[ARD - Lucky]

No, Sport to Economy switch only affects trans shift points. Again we're talking M4.3 and M4.4, ME7 and later is different.

Edited by ARD - Lucky, 07 September 2011 - 10:48 PM.

[lookforjoe]

Nice video documentary!

Right - now where's the ME4.4 w/COP?

Just kidding, I know you are keeping it in mind.

Curious though, what about setups like mine that use a Apexi AVC-R or similar boost controller? How do you work with that, since the ECU boost map isn't a consideration?

[Keep Calm Chive On]

I love the level of education you provide on top of a stellar product. I remember the Turbo 101 Video when you working at "the other place" haha and even that helped many many people understand what exactly is going on in their cars other than just expecting magic to happen. I can only imagine the amount of dumb calls you cut down on (like mine haha) after having such a clean video basically hold our hand (maybe cup the balls).

Ballerness x 10. Makes me wanna take my pants off & swim in my parking lot naked shouting ARD ARD but people would think I'm drowning rather than the reality of me being "special"

[gmsgltr]

i can tell you which one of those non ard tunes you showed is probably a speedtuning file haha

awesome lucky, awesome. next summer i will upgrade from a green to a blue tune!

any hp comparisons?

[vmaxx]

I was just about to go with SpeedTuning but Lucky gave me better vibes, i'm glad I chose ARD instead.

[Keep Calm Chive On]

I love how everything we have discussed about me boosting hard & early due to the fact I dont have a catalytic converter and the whole duty cycle that I suspected long ago. I believe it was tuner "C" looked similar in regards to how my car reacts and being that I have exhaust flow beyond was was typical for the "catback exhaust" seeing as I have a 3" dp & no catalytic converter. The graphics really help explain my issue we discussed. You made it clear over the phone after we bounced some ideas off of each other. Its great to know that someone actually takes the time to not only develop a tune capable of smoother / safer / and stronger boost and power but can also explain it in detail and graphically back it up verses other tunes or tuners out there. Keep up the great work and I look forward to swimming out of my apartment to mail you an ECU so I can get my ARD on

[Kit Vexed]

so luck, bcs vs. tcv (for 850)?
what do you recommend and why?

[Keep Calm Chive On]

port sizing is different between BCS & TCV. BCS has a small port on (line i forgot) where as the TCV are all equal ports. I dont remember exactly but I think the BCS was a "bleeder" esk type boost controller where as the TCV is a "open/closed" system. Again I am not speaking on lucky's behalf and I am sorry if I potentially gave out any mis-information

[Kit Vexed]

awhile back just before Lucky left his old job, they had released the hd tcv for 850's.
until then, many ppl questioned the tcv vs. the bcs on the 850's and Lucky was testing them..
it was also around the time i'd gotten a stage III tune, so i went with the new hd tcv.
i haven't run anything other than the tcv since, including on my ARD tune..
sometimes (seldomly) i do get that "bounce back" boost where it goes hard and linear, then as the car shifts and boost changes, it softens up a tad then goes hard again (this isnt the car saving the rods either, it's all above 3k rpm @ this point).. this IS NOT drop off though.
"drop off" was the stage III tune i had, and this is when the car would spike up boost then drop off while in the same gear... see how that's different?
i know what im feeling is NOT a flaw in tuning (cause im hitting my target boost), but rather the boost control..
again, tcv vs. bcs?
Christian had mentioned how well a new stock bcs handled his ARD tune with 19t..
so it's got me questioning if i should get a new bcs for my ARD tune with 18t??
i wanted to hear it from the man.. i woulda PMed him but i wanted you guys to see as well which was best and why..
so Lucky, stop drinking coffee now lol

[cgally]

Luck, I sure hope you are able to share this type of info on Me7.

Lucky

[ARD - Lucky]

Lets talk wastegates and BCS/TCV.

First thing to identify is how the BCS and TCV are different. Put simply the BCS is a bleed system while the TCV is a block system. What does that mean?

The BCS by default routes pressure from the turbocharger outlet (red BCS port) to the wastegate (yellow BCS port). So if the BCS were never activated then the only boost pressure the car would build would be whatever the base wastegate setting was. So if the base wastegate setting was 5psi for instance, and the BCS were not activated or functional, then the vehicle would only make 5psi. Once the turbo has developed 5 psi the pressure would travel through the BCS to the wastegate and overcome the internal spring tension and open the wastegate door in the turbo, bypassing the exhaust pressure in the exhaust manifold and maintaining the 5psi. If you're still not sure on what all these terms mean watch the video "Turbo 101" on Youtube.

Now when the BCS is activated the red and yellow ports are still routed together, in fact they are always routed one to the other. The only thing that changes when the BCS is activated is the vent port opens (blue port) and allows the boost pressure coming in on the red port to be bled off into the intake tube after the MAF. The reason the turbo can't out flow the vent line (blue port) and keep the wastegate open is that internally in the BCS the red port has an opening that is only ~1mm in diameter relative the the 3.7mm diameter ports of the red and yellow lines.

The TCV in M4.4 is essentially the same however instead of bleeding off the boost pressure from the turbo (red TCV port) it simply blocks it. So the TCV is a simple 3 way valve. When it is inactive the TCV routes turbo pressure to the wastegate (red to yellow). When the TCV is active the turbo pressure is blocked and the wastegate is routed to the vent port (yellow to blue). Only slightly different but it is important to understand the difference for the conversation around using a TCV in a vehicle with a BCS.

Let's go further.
Why is it that only 5psi wastegate pretension can hold back 15psi or more of boost? MATH TIME!
The wastegate arm that connects to the wastegate actuator is 24mm long.
The internal wastegate arm that connects to the flapper is 12.5mm long.
So that gives us a leverage ratio of 1.92
The diameter of the flapper in the turbo is approx 0.880 inch, given the Pi R2 for area we get 0.607 square inches

This means that at 15psi there is 9.1psi against the flapper. Again the reason for this is that the flappers active surface area is less than 1 square inch.
With a leverage ratio of 1.92 that means the wastegate would only have to be pretensioned to 4.7psi to hold 15psi of backpressure in the exhaust manifold.

For any other math geeks out there please check my figures and make sure I haven't made a mistake.
Thanks!

Edited by ARD - Lucky, 08 September 2011 - 06:28 PM.

[ozzimark]

Awesome stuff Lucky. Just one thing though..

This means that at 15psi there is 9.1 pound force against the flapper. Again the reason for this is that the flappers active surface area is less than 1 square inch.
With a leverage ratio of 1.92 that means the wastegate would only have to be pretensioned to 4.7 pound force to hold 15psi of backpressure in the exhaust manifold.

Area * pressure = force

The question is then a matter of the wastegate diaphragm area and spring rate to figure out the appropriate crack pressure. I've always assumed that the Volvo wastegate number (ie: 300/70), is a measure of the actuator diaphragm area and spring rate, but I am not certain, and the units are unclear. Perhaps it's 300mm² and 70N/m?

[LloydDobler]

Is there a 1:1 pressure ratio on the intake/exhaust sides of a turbo? If not, you're starting off your calculations using intake manifold pressure rather than exhaust manifold pressure on the wastegate.

[ozzimark]

Nah, note that he stated 15psi of backpressure in the exhaust manifold. Granted, that's assuming atmospheric in the downpipe too, which is unreasonable as well. Exhaust:Intake pressure is likely to be well above 1:1 with most turbos.. probably above 2:1 as you push the limits of airflow out of the TD04s these cars come with.

[JHEIII874T5M]

Looking good Lucky, glad you're able to make these contributions.

[ARD - Lucky]

The main point of the last post was to get an understanding of how/why the wastegate adjustment is so important. Understanding that exhaust backpressure ratio (EBR) is dynamic is useful no doubt but not necessary for the 101 nature of this thread. For now I'm trying to just cover the basics for folks that either don't have information about or are unclear on.

Thanks for the correction Ozzi!

Appreciate all the input as this thread is for all of us, including myself. As much credit as you guys give me I don't know it all but together we all know more!

Edited by ARD - Lucky, 08 September 2011 - 09:10 PM.