[OldCrow7xx]

Originally Posted by outofphase

The short answer: 18 (much less 20) isn't safe with the amount of fueling the car has available and will shorten the lifespan of your turbo even more. That's why the DME doesn't like it! It ain't safe!

The long answer: Think of the wastegate like a door. On this door there is a spring that keeps it shut. This spring keeps the door closed until a certain boost threshold is reached. So, say that it's a 10psi spring. That means it will stay closed until the pressure reaches 10psi. When the pressure reaches 10psi, the door opens, and an actuator arm pushes open the wastegate valve.

Once the pressure reaches 10 psi and exceeds the capacity of the spring, the wastegate will stay open until the pressure goes back under 10 psi. This excess gas bypasses the compressor wheel and is released back into the exhaust system via a wastegate valve.

So, in theory, if you have no boost control whatsoever, you should rarely be able to make more than 10 psi of boost.

Things get a little more complicated when you add in boost control.

On PWG cars, boost is controlled via a solenoid that allows vacuum to reach the wastegate actuator (the aforementioned "door"). This is modulated via a pulsed signal from the DME. The DME decides how much/how quickly to "pulse" this door based on a number of different things. The frequency of the pulse is represented in logs as WGDC (wastegate duty cycle).

Take a look at this super-zoomed-in snapshot of one of my logs. You can actually see boost control in action. (I'm EWG but the concept is the same)



The green line is WGDC (the frequency of the "door" opening/closing). The orange line is target boost. You can see they both follow roughly the same path. When the DME wants to change target boost, the wastegate follows suit.

Now, this system isn't perfect. But there are lots of little things that could be happening. The spring could be too stiff for some reason (not allowing the actuator to open early enough), the actuator arm could be faulty, the boost control solenoid could be bad, the line from the solenoid could be cracked or have a leak... I could keep going and going; I'm not trying to scare you, I'm just trying to explain why increasing target boost to fix boost creep is an awful idea.

When boost is too high the DME will likely keep your motor safe, with throttle closure, reduced timing, limp mode etc., but it's still not good for your turbo.

It probably lets you edit the MPPK because it's a BMW calibration -- most tuners (including PTF) don't want you to have access to their tune because it'd be giving away their "secrets". Regardless, you shouldn't be able to change the OTS PTF maps. And if you can, please give me your login so I can spend hours studying them

I'll say it again -- open a ticket plz

Yeah because in theory if you cared enough, and it seems we do, you could reverse engineer their maps and make your own tweaks during the translations.

My plan was to study the BM3 OTS map and crosswalk the changes I liked back to the MPPK map in the editor. You could in theory eventually evolve the MPPK file to be a variant of the BM3 tune with your own signature on it.

This method is how now deceased DJ Avicii developed his signature sound. He said he spent years reverse engineering other people's sound patterns before he ever made music. He also never played any instruments. When he re created them he made his own subtle tweaks and adjustments where he saw fit. Pretty interesting.

So I guess lemme make sure I understand, with a spring alone you can only make as much boost as that door will hold until it opens.

With the solenoid and computer control it can modulate the door beyond the flat interval of say 10 pounds to 15 like BM3 does?

But you are saying to run 18 or 20 is unsafe to this eco system of parts!?

How do I safely run more boost with my current hardware, or is that not a possibility....

Thanks for the details man it helps a lot!

[outofphase]

Originally Posted by OldCrow7xx

So I guess lemme make sure I understand, with a spring alone you can only make as much boost as that door will hold until it opens.

In a perfect environment, yes.

Originally Posted by OldCrow7xx

With the solenoid and computer control it can modulate the door beyond the flat interval of say 10 pounds to 15 like BM3 does?

Yes.

Originally Posted by OldCrow7xx

But you are saying to run 18 or 20 is unsafe to this eco system of parts!?

Yes. And pointless without a larger turbo and being tuned for it. The issue is you're overboosting.

Originally Posted by OldCrow7xx

How do I safely run more boost with my current hardware, or is that not a possibility....

Get your boost creep issue sorted first, then install your DP and flash stage 2. If you still want more, upgrade the turbo/fueling.

Originally Posted by OldCrow7xx

Thanks for the details man it helps a lot!

No problem!

[OldCrow7xx]

Originally Posted by outofphase

In a perfect environment, yes.

Yes.

Yes. And pointless without a larger turbo and being tuned for it. The issue is you're overboosting.

Get your boost creep issue sorted first, then install your DP and flash stage 2. If you still want more, upgrade the turbo/fueling.

No problem!

Can you explain why everboosting is bad? And how BM3 stage 2 runs more boost safely?

Then I think I'll be up to speed lol

[outofphase]

Originally Posted by OldCrow7xx

Can you explain why everboosting is bad? And how BM3 stage 2 runs more boost safely?

Then I think I'll be up to speed lol

More boost = more air. More air needs more fuel. Uncontrolled boost can surpass what the stock fuel system can reliably supply, leading to lean AF ratios and potential engine damage (detonation). The DME will try to prevent this, but it's not perfect.

More boost isn't necessarily bad -- hence stage 2 or a custom tune. More boost accompanied and controlled by the proper tune, fueling, and mods is fine. Uncontrolled boost is dangerous.

[OldCrow7xx]

Originally Posted by outofphase

More boost = more air. More air needs more fuel. Uncontrolled boost can surpass what the stock fuel system can reliably supply, leading to lean AF ratios and potential engine damage (detonation). The DME will try to prevent this, but it's not perfect.

More boost isn't necessarily bad -- hence stage 2 or a custom tune. More boost accompanied and controlled by the proper tune, fueling, and mods is fine. Uncontrolled boost is dangerous.

Ok so it's not going to stress the turbo, it's that the AF could get too lean.

I've asked this a lot and never gotten a direct answer but it seems like you may actually know- what is the harm of running stage 2 with my factory downpipe?

Seems like that would be more boost with more fuel within parameters of OEM hardware, the only thing I could try to reason out would be spool time.

It would take longer to hit boost target with factory DP because of restriction and friction?

[harkes]

Very "interesting" to see that PTF allow 3psi overboost without throttle corrections... Some leeway has definitely been given on the safety compared to the stock map.