Hi all, thought I would try the collective brains to try figure this out.

I have just replaced my SD4 EGR valve as the old one was sticking - 180k miles.
Installed all parts back and all sensors, no damaged wires etc.

Now when starting, it idles very rough and dies in about 20 seconds - sounds like it is choking.

if I discionnect the mass airflow meter at the airfilter, it idles normally and revs up to 2500 - but get reduced engine performance message and goes into limp mode - but drivable. Reconnect Mass airflow and the engine shudders shakes and dies.

I have SDD so have done a airflow path relearn to setup the EGR valve.

Have i just inadvertently had the Mass Airflow die on me too, puzzling as the car ran well (except for know EGR issue) prior.

Codes come up as mass airflow when disconnected, but no codes when connected, but does not idle - splutters and dies.

Any advice welcome - going to order a new Mass Airflow just in case.

thanks, Dino 2011 SD4 HSE Auto Ipanema Sand - and behaving like a mad cow!
2008 TD S Auto Santorini Black - the other halfs murder mobile

You need to run an air path calibration, or the ECM doesn't know the parameters of the new parts fitted. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, the daily driver.
1972 Hillman Avenger GT, the project.

Says thaey have SDD and have done an air path calibration. Jules

Got it sorted. Faulty new EGR valve - SD4 uses different setup - cleaned old one and now working (for now). Had to redo learning with SDD and now much better. Slight hesitation that the 2010/2011 know for so may look at a remap while sorting a few other bits out.
Mass airflow sensor replaced and has made a difference.
At least up and running again and the other half can have hers back! 2011 SD4 HSE Auto Ipanema Sand - and behaving like a mad cow!
2008 TD S Auto Santorini Black - the other halfs murder mobile

Bad luck getting a faulty EGR valve - who manufactured it ? Jules

Changed the EGR to the correct Pierburg model, new vacuum bypass valve and actuator for the SD4 from BH0000001 (2010/2011) onwards. Replaced MAF sensor on air filter with correct one - make sure to check as laster BH onwards have temp sensor in this, earlier ones dont - car runs but get stall/misfires in temp above 15'C between 1100 and 1600 rpm. Correct later one with temp sensor resolves this! So in effect have replaced the enire emissions system to get it running smoothly again - smooth even power delivery and reduced fuel consumption. 2011 SD4 HSE Auto Ipanema Sand - and behaving like a mad cow!
2008 TD S Auto Santorini Black - the other halfs murder mobile