I took the 159 2.4 JTDM Sportwagon to my wonderful Alfa mechanic for servicing and intake system cleaning yesterday. My wife drives this car on her daily 60 km commute, that includes steady cruising at 60 or 80 KPH on the expressway, so it gets a good run every day. It has currently done 82,000 km. The mechanic ran the DPF clean process with his computer, which didn't take all that long. It was 38% blocked. He pulled off the EGR valve and the photos below show the nasty state it was in. He then poked his endoscope camera down the intake and in between cleaning the black gunk off the lens we could see the build up in there too. The EGR valve was then taken off and cleaned and put back on for the cleaning procedure. The square gasket was the original one with the large square hole.
My mechanic recently purchased a special diesel cleaning system from the US that connects to the EGR intake and runs a cleaning agent through the intake system with the engine running. You also put an additive in the engine oil and another in the fuel tank. It takes something like three hours to go through the process, which runs automatically and creates a fair bit of smoke. It also goes through the DPF and gives that a further clean. After it was finished you could see shiny metal in the intake. It doesn't clean it absolutely perfectly, but it is vastly better than before. I gave him the go ahead to make two EGR blanking plates out of aluminium, to disable the damn thing. I have done extensive reading on this site on the subject and passed the info onto my mechanic, so we both have a very good handle on it. We are going to monitor the condition of the intake in twelve months time, but we expect it to be far cleaner. For the time being we will ignore the warning if it comes up. The oil and filter were then replaced.
The engine was running much quieter afterwards and you could feel the increase in power and responsiveness. It will get even better after a few more starts, as the computer re-calibrates.
It seems to me that the EGR system is bad, undeveloped technology, forced upon the manufacturers by ignorant politicians. I think it can maybe make a small difference when the car is brand new and the system is nice and clean. As it inevitably starts to clog up in a fairly short time, then surely hydrocarbons increase due to poor combustion and the need to put your foot down more? Then more is produced in the DPF cleaning process which happens more often in lightly driven cars. The horrible gunk is a combination of the oil from the PCV and the dry soot from the exhaust and is baked by the heat, making it hard to remove. I am damned if I going to allow our lovely engine to be ruined by such a thing. As a mechanic myself, I can't bear to see that sort of crap in my engine. Perhaps one day a manufacturer will come up with a system that doesn't cause those problems.
2004 GT 3.2 V6, Grigio Stromboli
2008 159 ti 2.4 JTDM Sportwagon, Grigio Stromboli
1989 75 3 litre V6, black
1988 75 3 litre, red, (son's car now)
2000 156 TS 2 litre, Cosmos Blue, (daughter's car)