[OpenFlash]

Ok.. so here's what we've learned so far about v29.2 (and presumably the v81 DME).

The "manipulation" code that is triggered by aftermarket tunes has to do with exceeding a certain mass airflow limit. Being clever folks, the engineers at BMW know that it was useless to measure airflow by using the easily manipulatable MAP sensor. So instead it appears that they are looking at:

1) Fuel output, which can be used along with Air/Fuel ratio to calculate mass airflow.

and

2) Wastegate control duty cycle, to make sure it stays within the range of a stock vehicle. If it goes too high, it can be determined that boost has been raised.


Fuel output can be represented by monitoring short term fuel trims. This can be logged on any decent OBD-II scan tool. On a stock car, STFTs typically stay within +/- 10%, depending on bolt-on mod, ambient conditions, running conditions, etc,. For those who don't know STFT is a closed loop fuel correction the factory ECU adds (or subtracts) from the raw fuel map(s) in order to keep AFR at the desired target. AFR is measured by the wideband o2 sensors located just downstream of the turbos.

Current tuning systems induce fuel enrichment by biasing the wideband signals. This induces a more positive STFT. Sometimes this goes as high as the ECU allows (+33%). We had a hunch that this would be something that the ECU could eventually monitor. It is, in fact, the last quantifiable tuning artifact that we know of.

Our target goal was to keep STFT within the range of a stock car (+/-10%) while still providing proper on-boost fuel enrichment. So we started our homework by monitoring the system fuel pressure. Fuel pressure in the DI system peaks at 3000psi at peak torque. Then it tapers as torque papers off, reaching just 1600psi at 7000rpm. So we got control of the fuel pressure control system. We left peak pressure unchanged. Instead, we just contoured the pressure curve to me more suitable for a car that makes more higher rpm torque. This basically give us 30-40% more fuel output at 7000rpm. More importantly, it provided this extra fuel without running abnormally high STFTs or out-of-spec injector on-times. Basically, we can't think of any way that the overall system could be more diagnostically invisible/immune to throttle closure. Either with 29.2 or anything else that I can imagine BMW throwing at us in the future.

Here are some logs I've done with this new "Doomsday" map (14.5psi peak) on my car (fully catless with dual intakes):





The blue line represent actual throttle position (87% is full throttle). The red line is Short Term Fuel Trim Bank 1. Notice that even when running WOT at full boost (12-15psi), STFT stay within the same range as they do when running off boost. Under no circumstance do STFTs max themselves out at 33% just begging for Big Brother to notice And on top of that, we've actually managed to make the ECU less prone to closing throttle under dynamic driving conditions. Throttle closure was more apparent when the car is stock.

Right now, a handful of people are running this map (or variations of it). By no means am I encouraging fraud with respect to diagnostic invisibility. I just want these cars to drive properly when hopped up. BMW should have no control over what you do to your car once you own it.

More info to come....

Shiv

[sambonator]

Great info and work!!

[e90AW335i]

Originally Posted by sambonator

Great info and work!!

+1 As always.....

[Robertbog]

well done sir

[FirstClass]

Originally Posted by shiv@vishnu

By no means am I encouraging fraud with respect to diagnostic invisibility. I just want these cars to drive properly when hopped up. BMW should have no control over what you do to your car once you own it.

As far as I was aware the new software in no way hampered tunes, it only made them more detectable. Either that is incorrect or you're full of it and you are doing this purely so people can commit fraud. Which is it?

P.S. Obviously you're saying you're not trying to hide tunes for legal reasons, but it's pretty clear that you are. Better off just being honest.

P.P.S. From an engineering standpoint, you're a brilliant at reverse engineering, well done.

[Hunter399]

^?

[Robertbog]

Originally Posted by FirstClass

As far as I was aware the new software in no way hampered tunes, it only made them more detectable. Either that is incorrect or you're full of it and you are doing this purely so people can commit fraud. Which is it?

P.S. Obviously you're saying you're not trying to hide tunes for legal reasons, but it's pretty clear that you are. Better off just being honest.

Well the car also throws some serious limpage unless the problem is taken care of.

[FirstClass]

Originally Posted by Robertbog

Well the car also throws some serious limpage unless the problem is taken care of.

I stand corrected. Hence why I gave the two options.

[SteelTorque]

Originally Posted by FirstClass

As far as I was aware the new software in no way hampered tunes, it only made them more detectable. Either that is incorrect or you're full of it and you are doing this purely so people can commit fraud. Which is it?

P.S. Obviously you're saying you're not trying to hide tunes for legal reasons, but it's pretty clear that you are. Better off just being honest.

P.P.S. From an engineering standpoint, you're a brilliant at reverse engineering, well done.

Don't worry about us, man. Really! Just enjoy your 328xi.

[OpenFlash]

Originally Posted by rmfast

Interesting info. As I feared you are getting around this fuel check by overrunning the already weak fuel pump. You say that you are running 3100psi, but I saw another log showing the factory pressure peak at 2600psi. That means you are running fuel pressure at around 20% higher than stock. It kind of makes sense since your short term fuel trims dropped 20%. That extra pressure has to negatively impact fuel pump life. Who is going to pay for those claims? BMW? The unwitting end user?

Here is a chart I found showing the 2600 psi number from this thread:
http://www.n54tech.com/forums/showthread.php?t=1230

You are presenting wrong information. Good for you.

Shiv

[e90AW335i]

Originally Posted by shiv@vishnu

You are presenting wrong information. Good for you.

Shiv

Are you going to explain or just shoot it down?

[OpenFlash]

Originally Posted by e90AW335i

Are you going to explain or just shoot it down?

It's not even worth trying to explain anything to someone who is willing to make himself look stupid just to shit on someone else's work. For instance, he pulls this "3100psi" figure out of no where. Something that isn't even right. And he also states that running higher pressures will "overrunning" a pump that is directly driven off the engine. Pressure is controlled by a relief valve, not pump speed. He also doesn't seem to understand that fuel flow is the square root of the change in pressure.

He is the same guy who asked Riss Racing about a refund if he doesn't find oil in the catch can. He's a troll, nothing more.

Shiv

[modster]

Whatever it is, I will beta test for you if needed!

[b335i]

Nice work Shiv, and Great read!

I replied to that email from earlier too...

[Mattscott]

Nice info Shiv, great read!

[Mattscott]

Originally Posted by rmfast

You know the fuel pump costs around $1500 to replace right?

$950 + tax for the part if you want to install it yourself.

[Duke]

Great post shiv!

[ArmyBimmerDude]

Hey great job Shiv. Don't let the negative posts drag you down. You've been here a long time taking supporting the forum. Thanks

[OpenFlash]

Originally Posted by rmfast

First I'm sorry I misquoted you on the 3100psi, I read your post and you said 3000psi. So there is an approx 400 psi difference between what you stated and what the other chart I found showed. Then again who knows what pressure you are actually running since there is no way to log it and how accurate the other information is as everyone seems to have an agenda.

If you are saying that more pressure won't damage the fuel pump, I disagree with you, but at least we can agree to disagree on that. It sounded an awful lot to me like you were claiming you were not increasing the pressure over the stock value to me.

What is really scary is if you do the math. To get from 33? % more fuel to 10 % more fuel would probably require an 800-1000psi fuel pressure increase or more.

The real solution to this problem isn't blowing up the fuel pumps, its flash software that allows proper fueling.

If you take more time to actually read and less time to hate, you'd know that I didn't raise the peak pressure. And you might want to do a bit more research on DI fuel pumps (and their failure modes) before continuing this argument. While you're at it, run a log on your car and see what the peak fuel pressure is.

Shiv

[RiXst3r]

Just wondering, what made you change your mind about the STFT's ?

I have heard several people battling about weather or not it actually does this... I just wondered what made you change your mind...

thanks
-Rick

Originally Posted by shiv@vishnu

Hi guys,
Spent the past week doing testing on the new 29.2 ECU update.

....

I had initially expected it to monitor fuel output (short-term fuel trim in particular) and protest when it seems abnormally high fuel consumption (typical when running higher than stock boost). It didn't seem to exhibit this behavior at all.

...
Shiv

[Duke]

Originally Posted by shiv@vishnu

Yes, actual R&D is more than just typing on a keyboard from your parents house

hahaha OWNAGE!

[OpenFlash]

Originally Posted by RiXst3r

Just wondering, what made you change your mind about the STFT's ?

I have heard several people battling about weather or not it actually does this... I just wondered what made you change your mind...

thanks
-Rick

There are two issues at hand here. It's the STFT issue that seems to trigger the manipulation code. It's the wastegate duty cycle abnormalities that seems to be the leading contributor to throttle closure.

Shiv