Thanks Ralf...I couldn't have asked for a more consise how to! Appreciated. Have you ever been iintoor had any issues with the egr valve? I have a very lumpy tickover, moreover when it first starts. It may be a slightly dodgy injector, but thought I might investigate the condition of the egr before taking it further. Thanks again! Adam
My EGR was full of coke to the extent that the valve jammed/couldn't move freely.. so it threw up an error light.
The EGR is behind the head.. but it has a flared heat exchanger type device (?) and a corrugated pipe feeding it from the exhaust manifold. That whole section gets soot in it.. but if yours is like mine, the clamp where the engine end of the pipework attaches to the manifold will be rusted and difficult to access.. so spray it up with penetrating oil... if you can get a spanner or socket on it, and it feels like it's going to come off, then undo it.
You'll have to remove the plastic air inlet pipe from the intercooler to get everything out.. but there's still a fair bit of pipework, cables and plumbing down there... so it's easy but not simple. I think there's one other bolt holding the pipe to the block.. but otherwise it's just supported at each manifold end.
If you can undo the exhaust-end clamp and remove the whole section from the exhaust to the EGR then that will allow better cleaning access... but on mine the exhaust-end bolts looked moody and I didn't want extra drama if one sheared, so I only unclamped the EGR pipe at the corrugated pipe joint down at the back of the engine, and then and at the EGR itself.
The EGR pipe clamps are like a hose-clamp with a triangular ridge down the middle, that fits over the flared ends of the two pipes it's joining. There's a gasket in each joint too, so watch out for those falling out. It's easier to remove/refit the joint under the thermostat if you loosen both EGR clamps, so the corrugated pipe can rotate.. it makes lining up the EGR and the bottom connection much easier than if one of the pipe is rigidly bolted. It's out of sight and difficult to access.. so you will probably swear a lot, after the clamp is one but the gasket has fallen out, or the other way round, for the 20th time.. .
The EGR itself is bolted to the inlet manifold and is relatively simple to remove. I vaguely remember one bolt is too long to remove without fouling on something (the fuel filter or bulkhead etc.) but with some jiggling, you can just about do it.
Cleaning the EGR is just a case of wiping, spraying, scraping the soot off and working the valve backwards and forwards by hand to make sure it's "free".
To preserve mine, I blanked the top pipe (you can get oval shaped blanking plates on fleabay) using a solid oval plate. There are some with holes in them to induce swirl and reduce fouling (I think there was a factory recall/part like this on the MJets?) but I didn't want to experiment and do it all again, so I just blanked the pipe where it joins the EGR..
I think I also blanked the pipe from the EGR into the inlet manifold, to prevent gas/oil going back into the EGR from the inlet manifold. Your inlet manifold will be nasty (indirect injection) so you'll see why. Allow some time for de-coking the manifold.. but it's tricky as you don't want to dislodge carbon and have it fall into the cylinders, in case it jams a valve open. I used some spray cleaner.. but it hardly touched it. It's probably a job for if ever the manifold has to come off..
Back on topic... On mine, I would have preferred to put a blank on the EGR pipe down by the exhaust manifold to stop that pipe filling with coal.. but I didn't want to try unbolting that end.. so I only blanked it at the EGR end. My EGR is sealed at both ends so should be immaculate.. and it's never givem me any trouble since.
Don't remove the EGR altogether, if you decide to blank it off.. since the car will notice that the plug isn't connected/EGR isn't responding.. just leave it there isolated behind the blanking plates; without any gas/soot bothering it, it'll last forever. My EGR is the OE one, with 210,000 miles now... so it's not a weedy part in itself.
The blanks affect how much NOx the car produces but the car drives better without half the intake air being re-cycled exhaust gas, so the benefit is more BHP and more MPGs, theoretically.. If you're Green and live in the City then NOx is a bad thing.. but my beast was usually out in the sticks and motorways, so hopefully the slight extra bit of NOx didn't kill anybody..
The blanks don't affect CO2 and the car has been fine for emissions.. it's more smokey than anything else (a new turbo actuator boost valve sorts it- the OE Pierburg ones tend to last about 100k).