AGR Bypass: LMM Monitoring Explained

Hello,

The EGR pipe on my E300TD had a crack.
It now costs 170,- net, and I didn't want to deal with that.
So, it was disassembled, welded, and then reinstalled.
Unfortunately, it only lasted about 5,000 km. This stainless steel material is very thin.

Now I need to figure out how to proceed.
When the EGR valve is closed, the engine goes into limp mode.
because the mass airflow sensor is reporting that too much fresh air is being drawn in.

Is there a way to solve this problem with the LMM?
I was thinking about adding an extra air duct from the air filter box, located behind the mass airflow sensor (MAF).
Then the entire amount of fresh air flowing will not be measured, and the engine will not go into emergency mode.
What should the diameter of the hose be?

Best regards, Rodion.

rodNeX wrote:

Hello, The EGR pipe on my E300TD had a crack. It now costs 170,- net, and I didn't want to deal with that. So, it was disassembled, welded, and then reinstalled. Unfortunately, it only lasted about 5,000 km. This stainless steel material is very thin. Now I need to figure out how to proceed. When the EGR valve is closed, the engine goes into limp mode. because the mass airflow sensor is reporting that too much fresh air is being drawn in. Is there a way to solve this problem with the LMM? I was thinking about adding an extra air duct from the air filter box, located behind the mass airflow sensor (MAF). Then the entire amount of fresh air flowing will not be measured, and the engine will not go into emergency mode. What should the diameter of the hose be? Best regards, Rodion

Hi...

Bypassing the system can be tricky. You would need a cross-sectional area roughly the same as the LMM (Ladedruckmessmodul), and also streamlined connecting pieces; it's not a simple task. The fresh air requirement at idle is approximately 50% of the amount of air the engine would normally draw.
The entire system would also need to be controlled in such a way that, at full load and with a specific accelerator pedal position (xyz), the mass airflow sensor (MAF) measures the full air mass again. Otherwise, the engine control unit (ECU) will regulate the engine as if it were in a smoke reduction mode.

I've also seen these thin, flexible tubes used in a universal way. The only way I can think of to fix it, if it keeps breaking in the same spot, would be to somehow patch it. Perhaps the most cost-effective and temporary solution would be to create a custom sleeve and seal it with hose clamps.
Another option would be to modify the software to set the AGR (Agricultural Guarantee Rate) to nearly zero, but this still constitutes tax evasion and fraud, and it's not cost-effective for the intended purpose.

I would try to repair my new pipe, or at least put in some effort to do so. You won't be happy with any other solution.

Okay... Thinking about it, I could route a portion of the air around the mass airflow sensor and...
Furthermore, I would need to divert the pressurized air and connect it to the valve.
All in all, it's too complicated
Patching is difficult because the pipe is cracked at an angle.
And the angle is a kind of slightly flexible corrugated pipe.
I guess I'll just have to bite the bullet.

'Thank you anyway!'