A4 B7 2.0 TDi EGR valve exhaust inlet pipe

Hi all,

Been having lots of problems with cold starting, lumpy idle, then a P0401 code - exhaust recirculation low flow. It's a 2006 BRD engine.

Read a few posts which pointed me in the direction of the EGR valve. I removed this yesterday, and sure enough it was caked up with carbon deposits. I started cleaning it, and while waiting for the ball and chain to fetch the carb' cleaner, checked the EGR valve actuator drive gears for wear as had been mentioned several times, and found the teeth on two of the gears completely worn out.

Checked, and these wouldn't mesh to open the valve, so wouldn't, I presume allow the exhaust gases to be mixed into the fuel / air mix to dilute the combustion mix to reduce NOx production.

Saved me a job of cleaning the EGR, and I've ordered a new one from GSF, however, there's LOADS of carbon build up in the stainless steel exhast gas inlet pipe. I'd like to remove and clean this pipe, but can't see where it goes, and how to remove it?

Anyone have any ideas please?

Thanks very much in advance

Scrapped the idea of taking that pipe off, and instead attached a 'bung' of sponge to a wire, and pushed it down the pipe beyond the most blocked bit. Then scraped the carbon build up from the accessible bit of pipe, and pulled the sponge pig out with all the debris.

Now getting carried away a bit, and have removed and cleaned (as best I can) the inlet manifold. While this was off, I checked the vacuum actuator that turns the flaps on the inlet manifold, and found it doesn't hold a vacuum. Ordered a new one, took the old one to bits, and the diaphragm inside it is damaged.

Anyone know what effect this would have??

Cheers for that. Yeah, I can't see this being the cause of the cold start problem, but if it stops the lumpy idle etc, it's a start!

Gonna try some injector cleaner next, as the glow plugs were changed about 8k ago, though I have read that some need the ceramic and some the metal glow plugs, and it can make a difference if the wrong ones are fitted

All sorted, replaced seals between EGR and anti-judder valve, EGR and exhaust inlet, and between EGR and inlet manifold. Replaced inlet manifold gasket, reset engine codes and BINGO!!! All working, and engine light has stayed off after about 50 miles now.

Lumpy idle has stopped, car runs much more smoothly, seems to pull from low rev's miles better too.

Cold start still a problem, so injector cleaner here we go!!