EGR woes

[nottsjohn]

Hi guys, ive got a 2.0tdi BRE A4 which has been fine for the past few years but the other day as i set off from a stop i noticed it suddenly lost power and i heard a chattering. Carrying on driving i noticed power would come back and then disappear again and would knock off my cruise control, so suspecting EGR i unplugged my MAF just to get me home, which indeed restored some power.

A quick VCDS check later and i found it to be an EGR fault to which i replaced it with a known good second hand unit and separated the old to find the teeth on the plastic cog had stripped.

Once id replaced the new egr on the car i performed an EGR basic setting and then took the car for a test drive and noticed that i no longer got the limp mode, but power doesnt seem to be what it was low down, but the turbo will kick in, mpg on my dash now reads about 8mpg at idle where it was 30ish before, there is a strong exhaust smell and when revved hard i get a little black smoke which i never got before!

Have i done something wrong, or could it also be my MAF is also playing up? VCDS shows no stored codes anymore and EGR spec and actual are reasonably closer now than they were when the old egr died.

[Gazwould]

What year is it ?

[Crasher]

Sounds like the new EGR valve is stuck slightly open.

[nottsjohn]

Its a 2006.

Crasher, i thought id properly cleaned out the new egr before fitting, but you maybe right. Do you know if there is any kind of "bedding in" period after performing basic settings?

TIA

[Crasher]

The EGR valve does not need setting up on those, you can test it’s function in Basic Settings. It MAY help to clear the learnt values in Adaptation 10 entering 0 and then clicking save.

[adani24]

I had something similar in January this year.
I went all out whilst under the bonnet:
Replaced the air filter and fuel filter, sprayed PTFE grease on the turbo actuator rod and made sure it was free. checked for split vacum hose for the actuator. Cleaned the EGR and Anti-Shudder valve/Throttle body (whatever you want to call it) with about 5 cans of carb cleaner from Toolstation. EGR was clean but Anti-Shudder valve was full of Oil. Carefully cleaned it up.
After putting back to together the car felt better on the following weeks commute (plesibo effect?) So I replaced the gaskets for the Anti-shudder valve and EGR valve. This gave an instant improvement to the response and power.