BMR feels sluggish again

HI

After my BMR was running very smoothly with the new nozzles, I've recently noticed that it doesn't seem to be working at all in higher gears when it's warm.

The situation was absolutely horrifying: with an outside temperature of 40 degrees Celsius and a heavily loaded vehicle, it was impossible to achieve full acceleration without exceeding 2000 rpm.

It wasn't that bad, but the current log looks strange to me (see attachments).

I suspect the LLM.

Okay, bitte gib mir den deutschen Text, den du übersetzt haben möchtest.
The peak in the RPM graph in the middle was a lambda test - 1.3 is acceptable.
He was really slow during the last 15 seconds. I had a flat tire on the way, specifically while driving on a rural road.

m;

What are ordinary users supposed to think when they are constantly being told that they should only...
Upload raw logs I don't see any air masses?

Where is the original document with the data?

Have you ever checked the vacuum system for leaks? The boost pressure builds up rather slowly, as far as I can tell, and I haven't mixed up any colors.

Yes, I also realized too late that I had forgotten about the air masses.

The XLS file is an unprocessed log.
I wanted to save the helpful person the trouble of recreating the chart.

Here's a JPG so you can quickly see what I mean, and then the raw data AND the chart (i.e., the XLS file).

What's very confusing is that the N75 value increases (to 85%) and then immediately decreases again (to 66%). He really doesn't want to, you know.

A classic 3-8-11 log will still be necessary, after all.

m;

Quote:

I wanted to save the helpful person the trouble of recreating the chart.

The CSV files are directly linked with KDatascope in my setup. While the software is a bit clunky, it has everything you need.

The N75 valve seems to reduce boost immediately when the engine speed increases, if I remember correctly. Whether there is too little boost pressure or not, it doesn't seem to matter much.

Therefore, check the vacuum system.

HI

Here's the raw CSV data.

I will check the vacuum pressure, but that won't change the fact that the N75 valve won't stay at 85% until some kind of boost pressure is applied.

Hello Martin,

Quote:

It was absolute horror at 40 degrees Celsius outside.

Okay, what can you say other than that the response to the accelerator pedal is poor at low RPMs when the outside temperature is very high? It's the same for me (BRE).
It's something that could potentially be improved in the engine control unit software, but for some reason, it hasn't been.

Best regards, Rainer.

Hi,

I have the feeling that at least some things have changed in this area over time. There's a huge difference between the ASV and the CFHF in terms of "summer weakness." I don't think that can be explained solely by the large FMIC, because if you're idling and then accelerating from a stoplight, that shouldn't make a significant difference. But there is a difference, and it's so pronounced that with the CFHF, you really have to pay close attention to even notice a temperature dependency. It was very clear at ASV.

There must be some kind of compensation for that.

Best regards,

Jan.

Hi,
So far, it's only apparent that the boost pressure is lagging behind. What about the other air pressures? Is the VTG (Variable Turbine Geometry) operating smoothly? Is there sufficient vacuum?
hg
Herbert.

Quote:

I will check the vacuum, but that won't change the fact that the N75 won't stay at 85% until something similar to boost pressure is present.

Just found another BMR log --> same behavior from the N75 valve.

Just wait, it will get cooler - then the car and your common sense will work better again.

Okay,

Yesterday, it was a bit cooler.

At the end, full throttle - no more of that sudden drop in the LDD (Load Drop Distance) slope, it felt better.

Vacuum pressure at idle: -760 mbar.

The vacuum connection looks good in place, however, to properly assess the tightness, a T-connector should be used at the connection point so that all components are included in the testing loop.

And activate each actuator individually via VCDS in order to check the sealing of the actuators that are inactive in idle mode. So you've also checked the (basic) function of the solenoid valves during the wash cycle.

Here's another short video showing how the vacuum behaves when the N75 valve goes into "actuator diagnosis" mode.

The vacuum pressure was measured at the location shown in the image, specifically at the supply connection of the swirl dampers.

Whether I should, as was once common, occasionally add a memory ball (playfulness).

Huh? 40 degrees Here in Old Germany?
It wasn't that warm, actually! More likely in Croatia/Southern Spain.

I don't notice anything at all with my ARL, and neither with the T3, except that there's a little more soot with longer, full-throttle driving.

T3Surfer wrote:

Huh? 40 degrees Here in Old Germany?

It depends on the definition of "old."
That was on August 2nd in Alsace - 40 degrees on the windshield temperature gauge (MFA)!!!

Looking at the interaction between the N75 and G581, I'm close to shortening the VTG.
Then, the immediate reduction in the N75 valve opening wouldn't cause such a drastic drop in boost pressure.
Generally, the interaction works well... unless there's a problem that only occurs at high ambient temperatures - regardless of the engine temperature.

Because I have a recent log of the MWB 043, specifically from the last acceptable acceleration.

When comparing the log data (posts from September 6th and 8th), I cannot detect a sharper control signal for the N75 valve in colder weather, especially since the starting speed is different (approximately 1700 rpm versus 1400 rpm). Contrary to that, the N75-TV's torque curve actually decreases at higher RPMs (starting from 1700 rpm), which is common when the control error isn't too high.
It would be interesting to see how the fuel injection amounts (which generate the turbocharger's power) correlate with the actual load demand. Perhaps the heat is causing an additional exhaust system restriction.