After installing a new Pierburg EGR valve the car (2007 R320 OM642.950) is having issues where above 1800rpm the car starts shuddering as if its losing power.
Scanned the car and it's got no codes. I unplugged the MAF sensors and the car drives fine. i've double checked everything (connections/EGR is seated properly) and i can't find anything out of the ordinary.
Do new EGR valves need recalibrating?
Any ideas on what the issue could be is much appreciated.

Do you understand how EGR works?
Everyone I know has had issues with EGR.
Legally there isn't much that can be done.
Exceptions do apply for off-road use only.
There are several companies that sell tunes for the OM642.
Efficiency and reliability can be improved by tuning.

I would recommend that you research this on your own.
This is not legal advice.

Count me out on this one.
Last time I had problem with EGR was 25 years ago on Chevy. When I don't have clear explanation for it, I think my habit of "flooring it" from time to time, aka Italian Tuneups can do the trick.
As for OP trouble, technology changes from MY to MY, but if the valve has electronic module attached to it, very likely it will need pairing with ECU.
Do you have a scanner, who allows you monitoring EGR when on the road?

Why did you exchange the EGR?

Reason for changing was purely for preventive maintenance, as well as the car having an occasional hiccup. I created a post not long ago discussing the issue:

In the last year on about 3 occasions when accelerating between 2-3000 rpm the car jerks a bit as if it’s losing a bit of power accompanied by the sound of the turbo making a turbo flutter/compressor surge sound. It only lasts about 2 seconds. Turbo is original and the actuator has been repaired in the past. Also (not sure if it’s related), under very light load only at about 1300rpm it feels as if the car loses power a tiny bit then goes back to normal (rpm drops a tad).

I was hoping maybe the EGR was causing this?

I have an Icarsoft CR MAX (doesn't have an option to reset EGR adaptation), i can watch EGR values but i can't really drive the car as the symptoms are that bad. The car idles fine though and has no codes for the EGR.

From what you're describing, I don't think that has to do with the EGR, but I'm probably the wrong guy to ask about that...

However if you want to test this theory, see if it performs any differently with the EGR valve unplugged. If that's the issue, I would expect an improvement in drivability and an EGR code (unless having the EGR valve disconnected causes limp mode, which I'm unsure of) but if it still behaves the same then you know it's not that. Hopefully @kajtek1 will reply again, I believe he's pretty knowledgeable about this stuff.

Ok will give it a try.
If after unplugging the EGR and the car is drivable, would it be ok to drive it for about 15 minutes with the egr disconnected (want to get the car to a different location to fix it)?

Disconnecting the EGR valve will keep it closed, so as long as doing that doesn't cause your car to go into limp mode, it'll be safe to drive like that.

Just beware, that emission system in US models are under high control and neglecting them can lead to countdown, what very likely will leave you in the mercy of dealer.

Thanks both for the info.
I disconnected the EGR and the car drove really well (if not better than how it drove with the original EGR.
I've got the car booked in with a merc specialist to see if their xentry has an option to reset EGR adaptations.

Xentry doesn't have options for EGR adaptation but can help you to diagnose the car correctly

Thanks guys for the info.
If there are no options for EGR adaptations for Xentry, does that mean the dealership can/t do adaptations?
Thanks

As there is no adaptation for EGR in Xentry, the dealer will only get your car diagnosed correctly.

Maybe the EGR was not defective.

Ok thanks. Reason i ask is i took the car to my merc specialist and like you said their xentry did not have an option for resetting EGR adaptations.
So if I took it to the dealer, would they have an option for resetting it?

....no...but dealer and your MB "specialist" can diagnose your car to find out what:s defective as if your engine is old enough maybe just a pipe needs to be cleaned if you had a EGR fault code in the first place

Right ok. I informed the issues (as mentioned above) to the company i got the Pierburg EGR valve from, and they are saying they won't refund me as apparently the egr valve needs a "learn in/adaptation step needs to be completed before the car is driven". But how am I supposed to do this if there is no option to do it? So i bought a genuine EGR valve (merc specialist recommended it as aftermarket ones apparently have issues) and i'm worried if I install it without coding it the genuine one will have the same issues and i won't be able to return it, hence why i was thinking of getting the dealer to install the genuine part. Should I just put the new genuine in to see if it works?
FYI i don't think car had EGR issues prior to installing new one (as mentioned above).
I cleaned EGR pipe the other day, had no build up.
Thanks

Why did you change the EGR valve in the first place? Consider that it wasn't the original problem.

My scanner has an EGR test function, although the my car is 2014, so that may not mean anything.

Update.
Turns out if you buy a new genuine EGR valve there is no coding required. I put in the new one and it drives fine.
I highly recommend you do not buy the Pierburg EGR valve for the OM642 as apparently they need coding to the car even though there is no option to on Xentry.