dvdcore

I was suspecting the DPF too.. because in my case, i do not remember to have reached a higher speed than 230km/h since the removal process.
Beside the actual physical removal, i also had an ECU update to ignore the DPF.
But the fact is though, there are plenty of 35d's with DPF removed that go up to 280-290km/h. So something is wrong with our cars mechanical or software.
I will try on the Dyno, with a different ECU map tuned by someone else, to see what happens. And while this, to monitor the boost level readout.

Tiago

This problem appeared right after DPF removal on my car, even without the ECU calibration update to ignore the DPF. I forgot to say that even on light throttle (less than 20%) there is a power loss when reach the 230km/h mark and feels like a speed limiter. So turbo boost can't also be the issue because in this case it is making less than OEM max boost. If i keep the throttle all the way down from low speeds, it can go up to 250km/h. Then it goes into limp mode and i need to restart the engine to clear it.

dvdcore

You described it perfectly. It means we have the exactly same problem.
I tried going in manual only in 6th starting from 170km/h, and the limp mode triggered around 240-250km/h, exactly as you said.
Have to restart engine, to get boost again from the big turbo.

I noticed that after clearing the ECU fault errors, with the first acceleration the car also get this error: DPF failure/failed (someth like that) - exhaust backpressure too high.

Tiago

This can make some sense. Without the DPF, the exhaust flow velocity was increased alot. Once our exhaust has pressure sensors, maybe it is triggering a error due to high velocity exhaust flow and somehow it thinks that is the turbo that is making insane pressure.

dvdcore

Have you found a solution? I tried with different ECU maps, including stock one. For maps with lower boost, the limp mode was triggered a bit higher around 240 kph.

Tiago

With the new tune for EGR and throttle removed the problem gone away, so it must be related with the tune.

dvdcore

What do you mean EGR tune. You have it turned off now?
Regarding the throttle, you mean the percentage of how much the throttle pedal is being pushed down?

Puricele7e

I had the same problem with my 535d (stock, 84.000km, DPF still in), and it cleared only after restarting the engine.
Will have my DPF removed this summer, as well as a new software that "eliminates" both DPF and EGR, hope that the problem will be gone.

Vlad

PS: dvdcore, esti din Romania?

dvdcore

@Puricele7e : Da, din Romania.
If you find other fix for the limp mode, please let me know.

I wonder though why the EGR would have an effect on the "charge-air-pressure too high" error.

dvdcore

I forgot to mention, the following parameters are logged at the moment of the limp mode:

Coolant temperature: 100 C degrees
RPM: 3999 rpm
Gear: 5th
Boost: 2.510 bar
Injection pressure: 1638
EGR: 4%
Throttle pedal: 100%

Of course, the cause is the boost pressure of 2.510 bar , which according to my tuner should not exceed 2.3 at all.
Any ideas, which sensors are used to calculate the boost pressure level?

I suspect, part no5 (pressure sensor), in the following picture:
http://bmwfans.info/parts/catalog/E6...s_mount_parts/