[Dm]

Hi everyone

I have a question on the widely discussed BMS-Power Box that is intended to remap the accelerator by intercepting the signal from the pedal unit and substituting it with the generated one (at least this is my understanding of how it works).

Automotive manufacturers are supposed to pay a great deal of attention to the reliability issues of car electronics, and especially DME units. I assume they use specially selected components, employ various fault proof algorithms to make sure the car is SAFE.

Now to the point i wanted to bring up: lets assume that the chip in the BMS-Power Box hangs up while you are cruising on a freeway and sends DME a "full throttle" continuously while you are desperately trying to stop ? Sounds frightening, eh? Reminds me the Prius story.

To conclude: I would suggest everyone considering this thing to make sure it does not decrease the safety of the car. So far I think it does.

[///M3NACE]

noob

[e90ben]

Interesting point,

The Powerbox does not involve throttle control as you stated, all it does is intercept the signal and modify the Volts that it sends to the ECU, hence changing the throttle position that the car thinks its getting.

You don't need to press as hard on the pedal, as the car thinks your pressing harder than you are

The fail safe that BMW has in place is the Throttle Position Sensor, how do I know, because I had to have mine replaced due to faulty one, WOT broken or fixed was the same

The only way for a Modern BMW to get stuck at WOT, is if your foot or something pushes the pedal to WOT.

On a side note, there is also a fail safe that will close your Throttle body if you are at WOT and depress the brakes to full (ABS on)

[Dm]

Originally Posted by e90ben

Interesting point,

The Powerbox does not involve throttle control as you stated, all it does is intercept the signal and modify the Volts that it sends to the ECU, hence changing the throttle position that the car thinks its getting.

You don't need to press as hard on the pedal, as the car thinks your pressing harder than you are

The fail safe that BMW has in place is the Throttle Position Sensor, how do I know, because I had to have mine replaced due to faulty one, WOT broken or fixed was the same

The only way for a Modern BMW to get stuck at WOT, is if your foot or something pushes the pedal to WOT.

On a side note, there is also a fail safe that will close your Throttle body if you are at WOT and depress the brakes to full (ABS on)

Thanks for commenting.
Had to google what does WOT mean - Wide Open Throttle.

It should not essentially be WOT - lets say the BOX outputs 95% of full throttle after its firmware hangs up - then the failsafe algorithm of the ECU you mentioned will not work out and one can get into accident, right?


...

[Dm]

Originally Posted by ihsanshaik

noob

sometimes newbies do ask smart questions, dude

[ddigangi]

i wouldnt wory about what you posted but your points do have some validity to them

[e90ben]

Originally Posted by Dm

Thanks for commenting.
Had to google what does WOT mean - Wide Open Throttle.

It should not essentially be WOT - lets say the BOX outputs 95% of full throttle after its firmware hangs up - then the failsafe algorithm of the ECU you mentioned will not work out and one can get into accident, right?


...

I don't have the exact acceptable levels for the failsafe to kick in.


The key here is the BMS Box does not control the throttle position.

It simply modifies what the signal the DME receives.


DISCLAIMER: I am in no way telling you will not crash your car, or that the BMS box will not cause you to crash your car, or that the BMS box will not void your warranty. Any modifications done to your car are performed solely are your risk, and I accept no responsibility from my general comments

[mister wiggles]

i'd love to hear some of the vendors chime in. after all, it's our cars and our wallets that suffer if we need to take them into the shop for repairs.

[Dm]

Originally Posted by e90ben

I don't have the exact acceptable levels for the failsafe to kick in.

The key here is the BMS Box does not control the throttle position.

It simply modifies what the signal the DME receives.

DISCLAIMER: I am in no way telling you will not crash your car, or that the BMS box will not cause you to crash your car, or that the BMS box will not void your warranty. Any modifications done to your car are performed solely are your risk, and I accept no responsibility from my general comments

The bolded part is exactly what bothers me. The ability to modify the throttle position is what makes BMS Box unsafe to use in case it's firmware would hang up and stuck with full throttle output when you actually released the physical pedal.

I am wondering if BMW would certify it.

[Dm]

Originally Posted by mister wiggles

i'd love to hear some of the vendors chime in. after all, it's our cars and our wallets that suffer if we need to take them into the shop for repairs.

I think you forgot to mention lifes

[mike-y]

As said above, the BMX modifies the signal from the TPS. if the throttle signal comes in a 15%, the BMX applies a modification factor of say, 1.15x (for example). so the 15% throttle signal is modified by the bmx to show 17.25% when it gets to the dme. it does not replace the signal, so if the throttle is closed (at 0%), then the BMX will output 0% (0 x 1.15 = 0)

I'd imagine the bmw safety system can cut the throttle whenever the brakes are applied, like the Prius does. FWIW, toyota's acceleration problems did not include the Prius. The one incident involving a run-away prius in San Diego was pretty much proven to be a fraud after they analyzed the "black box" data, and showed the owner of the car pressed the brakes AND the gas over 250 times during the so-called incident. The Prius automatically cuts the motor off when the brakes are applied to save gas.

I haven't tried to brake and accelerate at the same time yet on the bmw though, so I can't say our cars do the same. If anything did happen, you could just turn off the car though. But to date, I haven't heard of one issue with the bmx, or juicebox, which has a similar throttle remap.

[mike-y]

but no, bmw would not certify a bmx. you install it at your own risk. if you don't think it is safe, then don't buy it. it's quite simple actually.

[Dm]

Originally Posted by mike-y

As said above, the BMX modifies the signal from the TPS. if the throttle signal comes in a 15%, the BMX applies a modification factor of say, 1.15x (for example). so the 15% throttle signal is modified by the bmx to show 17.25% when it gets to the dme. it does not replace the signal, so if the throttle is closed (at 0%), then the BMX will output 0% (0 x 1.15 = 0)

I'd imagine the bmw safety system can cut the throttle whenever the brakes are applied, like the Prius does. FWIW, toyota's acceleration problems did not include the Prius. The one incident involving a run-away prius in San Diego was pretty much proven to be a fraud after they analyzed the "black box" data, and showed the owner of the car pressed the brakes AND the gas over 250 times during the so-called incident. The Prius automatically cuts the motor off when the brakes are applied to save gas.

I haven't tried to brake and accelerate at the same time yet on the bmw though, so I can't say our cars do the same. If anything did happen, you could just turn off the car though. But to date, I haven't heard of one issue with the bmx, or juicebox, which has a similar throttle remap.

Good point - I read that all the recent BMWs have the break override system, however the thresholds are high, otherwise it would not be feasible to heel and toe. So yes - you can brake and accelerate at the same time. At least until the break override system engages.

[Mike@N54Tuning.com]

The factory uses a dual signal system where signal A is always double the voltage of signal B. The PBX takes in both signals independently and modifies each independently. If the system were to ever shut down (say a wire came loose) the signals would be pulled to ground and the ECU would throw a fault and ignore the pedal input. But say for some reason the PBX through some unlikely failure could fail pulling both signals up then signal A would no longer be double the voltage of signal B and the ECU would again throw a fault and ignore the pedal input all together.

Mike

[e90ben]

Originally Posted by Mike@N54Tuning.com

The factory uses a dual signal system where signal A is always double the voltage of signal B. The PBX takes in both signals independently and modifies each independently. If the system were to ever shut down (say a wire came loose) the signals would be pulled to ground and the ECU would throw a fault and ignore the pedal input. But say for some reason the PBX through some unlikely failure could fail pulling both signals up then signal A would no longer be double the voltage of signal B and the ECU would again throw a fault and ignore the pedal input all together.

Mike

From the

[Gavin@MMW]

Even if your doing 80mph on the highway and something happens to where you cant stop accelerating, the Brakes WILL stop you. WOT or not, the brakes are stronger then the engines in these cars and they will always come out on top.

and yes they have a fail-safe so once you slam the brakes the ABS cuts power and stops you anyway

[ska///235i]

And i think craven haD ran the pbx for many many miles

[philsteroni]

FYI the throttle flap on all n52 Bmw's is always open thanks to valvetronic. I'm assuming your all using slang when using the word "WOT". Just throwing it up there.
Being concerned about the reliability of the PBX is as logical as worrying about your calculator not giving you the right answer to a mathematical equation...It just doesn't happen. I would be more concerned about the long term engine damage the PBX tune could possibly cause (ie carbon build-up on your valves from the very rich fuel mixture). Not worth the 5 hp in my opinion.

[Dm]

Originally Posted by Mike@N54Tuning.com

The factory uses a dual signal system where signal A is always double the voltage of signal B. The PBX takes in both signals independently and modifies each independently. If the system were to ever shut down (say a wire came loose) the signals would be pulled to ground and the ECU would throw a fault and ignore the pedal input. But say for some reason the PBX through some unlikely failure could fail pulling both signals up then signal A would no longer be double the voltage of signal B and the ECU would again throw a fault and ignore the pedal input all together.

Mike

Mike,
What prevents the processor of the PBX to be locked up on failure while leaving the last valid output signals on the output digital to analog converters (DACs) forever ? In this case the 2 output signals will still be valid (one half of the other) and the ECU will not detect any error.
Thanks
Dmitry

[Dm]

Originally Posted by Craven 328

Even if your doing 80mph on the highway and something happens to where you cant stop accelerating, the Brakes WILL stop you. WOT or not, the brakes are stronger then the engines in these cars and they will always come out on top.

and yes they have a fail-safe so once you slam the brakes the ABS cuts power and stops you anyway

Craven, may be the breaks are more powerful than the engines, but the brake way will be far further and this can be not safe if there are other vehicles in front of you, right?

[Dm]

Originally Posted by philsteroni

FYI the throttle flap on all n52 Bmw's is always open thanks to valvetronic. I'm assuming your all using slang when using the word "WOT". Just throwing it up there.
Being concerned about the reliability of the PBX is as logical as worrying about your calculator not giving you the right answer to a mathematical equation...It just doesn't happen. I would be more concerned about the long term engine damage the PBX tune could possibly cause (ie carbon build-up on your valves from the very rich fuel mixture). Not worth the 5 hp in my opinion.

Really? Why do people ever use redundant computers at fault critical applications, if "calculators" never fail ?

[kfiend]

This is going to be an interesting thread. As your reliability question goes with most aftermarket mods, specially ECU related.

Now, where is the pop-corn....