APP changes without lifting off

[grutsch]

I did flash ECU with M3 (BM) SkyActiv-D Base (V1.02). After that I did a testrun and noticed at app. 2800 and 3700 RPM a drop off. So I did do a log. At the mentioned RPM the APP changed from 100% to 78% and 82% without lifting off my foot. What could cause this issue?

Also another question. How can you compare stock tune with for example the M3 (BM) SkyActiv-D Base (V1.02).

Thanks for any hint in advance.

Alex

[Steve @ VersaTune]

I've seen that on other logs. I assumed it was the driver. Thank you for clarifying that it is the ECU. I will look into it. It looks like some sort of limiter. Can you please take a similar log with the same parameters plus Intake Air Temperature B1S3, Engine Coolant Temperature, and Manifold Absolute Pressure Desired?

In the Tune Editor, you can select the tune that you compare the current tune to. Changed values are in bold. The default is to compare to stock. Mouse over a cell to see the comparison value.

[grutsch]

Hello Steve,
I did again a few logs on the road (all in 4th gear starting around 1500 RPM).
The first log you got I think must be an error from my site maybe I did lift off. Anyhow the hesitation when you accelerate is still there and starts at about 2500 up to 4000. You can feel a short hesitation app. every 250 RPM where the acceleration sort of stops (even the RPM climb). So I check add added other parameters and it looks like that as soon as the bypass valve switches on the waste gate solenoid cycle is starting to have a bigger span cycle. Maybe this is the cause of this.

Alex

[Steve @ VersaTune]

The compressor bypass valve opens and the exhaust regulating valve moves to the middle position at 2600 rpm. Then the regulating valve closes at 4000. Between 2600 and 4000 you are transitioning between the small and large turbo. After 4000 you're fully on the large turbo.

The current issues that I am aware of and working on is eliminating the dip in boost during turbo transition and the boost oscillation when on the big turbo.

Based on your newest logs, the boost oscillation doesn't look like an intake air temp issue.

[grutsch]

Thanks for the quick answer. Looking at some early logs where I also logged fuel injection amount desired I noticed that at 2050 RPM it is at 105 mm³/cycle and stays their up to 2700 RPM from their it continuously drops down to 85 mm³/cycle at 3500 RPM. Looking at the tables I found that the Injection Limit Barometer at 89.9 at given RPM is around this values. Even I did log the Barometric Pressure Value it did not record at all it was showing a fix value of 92 kPa. Is this table even in used?
Alex

[Steve @ VersaTune]

It's possible that there is another similar table that we have not found yet. There are often multiple tables for use under different operating conditions. IQ limit is the other big item that I'm working on. 105 seems to be the magic number that we can't exceed yet.