W251 R-Class EGR Issues

[ber5ien]

I am having ongoing issues with EGR system. The cars goes into limp mode. During the winter it was fine normally. During the hot water is gets worst for some reason.

Replaced a back pressure sensor with a new one. (OEM Mercedes)
Replaced Cable to back pressure sensor. (OEM Mercedes)
Changed EGR to aftermarket (no change) put back the original one. (Mercedes OEM)
Mechanic check the EGR it opens up / close.
There were split in the rubber for EGR valve pressure. That was fixed but probably made it myself during troubleshooting.
Checked the intake system using smoke (no issues, no leaks, all seals/gasket seems to be fine not leaking)

Car is Mercedes R-Class 2011 OM642 350cdi 263

I suspect maybe a cable is damaged the one which connect the EGR but correctly don't have any schematics and not sure what to check

Any ideas would be great.

Thanks

 

[ber5ien]

Does this looks like electronics issue?

 

[star10]

Check chrome tube in the front of engine for clogged, where EGR enter in intake manifold-fault for positive deviation.
Also you have electrical fault for EGR valve, post VIN to send you circuit diagram.

 

[ber5ien]

I have cleaned both of these pipes and the connecting element.
The Y rubber bit had a hole and was replaced as well.

 

[ber5ien]

At the moment I would like to verify that 5 pin socket connection.
On the computer I have seen a percentage of Egr as -7.5%. So normal normal then -7.5 %.

 

[Norway]

I had same issue, I can recommend EGR delete.

 

[ber5ien]

I have asked two tuner both says that it might be something else. A bit of comedy. Just want to get that fixed. Thanks for info.
Have you used someone or did it yourselves?
What was the cost?

 

[eurocar504]

Here is the electrical function diagram if that helps.

 

[eurocar504]

Here is the wiring diagram for the CDI unit which includes the EGR positioner Y27/9 with the 5 pin connector (page 6).

 

[eurocar504]

You are right to focus on that 5 pin connector.
First, make sure that none of the pins are damaged of course.
Then check if you have reference voltage between pin #3 and #4 (that should be fine because that also feeds the crank sensor and others).
Lastly, check continuity to CDI N3/9 module (pin#3 goes to N3/9 pin56, #5 to 18, #2 to 72 and #1 to 96).

I think pin #1 and 2 are the neg and positive for the motor of the valve. Pin#5 is the signal from the position of the valve. Pin#3 and 4 are for ref voltage and common to lots for other sensors.