Hi all.
My name is Mark Harris and I've just registered on this site. I have a 2006 2.2Dci Espace, with only 22,000 miles on it and so went looking for EGR stuff online and arrived here.
I tend to do my own work on cars, and despite being a Pilot by trade, am well read on car mechanics, as well as my passion of motorbikes. Unfortunately, our local Renault dealer is staffed by cynical types so is not easy to deal with, and our car is still under the curse of it's manufacturer's warranty. only april till I can get the tools out!
Roy, I fully understand your dismay. I really do. I spent a few hours trying to treach the local Vauxhall Technicians how a thermostat worked, because they didn't have a clue as it didn't generate a fault code! Enough said.
Ian. The EGR valve on a 2.2DCi Espace Mk4 or 5 should be a solenoid electronic one. This should be shut when de-energised, and the two chambers withing the body will be sealed off from each other. If yours was open, then it was sticking and that's not good. The Turbo was pumping air out of both valves and thus your engine was probably getting no more than atmospheric pressure, yet the airflow meter and any air pressure sensor would detect all was normal and allow the ECU to give full fuel as per revs and your foot pedal position. Result./...no power and loads of soot.
As Roy will no doubt agree, the fundementals are oft forgotten. A Diesel is not like a petrol engine. It does not rely on a correct air/fuel ratio to produce combustion, thus correctly ratioed air/fuel is not premixed and fed to the engine via a throttle to restrict airflow to adjust power made.
A Diesel always gets a full lung-ful and does not have that throttle butterfly. The power depends on fuel supplied...up to the point where it gets too much and then the excess will come out as soot.
Old simple diesels demonstrated it well. You could leave a cloud of black soot behind you and by lifting the pedal slightly, stop the soot cloud without any reduction in power.
Modern engines are covered in electronic valves, pumps and clever stuff, but at the heart of it, if the engine is fed too much fuel for the air it breathes, it will generate soot. Simple as that. Stopping it is less simple.
Why does our Espace fill the EGR with soot? Too much fuel. (You can see this by the fuel consumption- mine's giving 15.2mpg around town
) But the Fuel is metered according to an ECU based on Airflow, Absolute pressure, revs and pedal position. So if the fuel is right, the obvious is NOT ENOUGH AIR! Again, this is a fundemental truth, and often not covered by a fault code.
Either; dirty air filter, knackered turbo, sooted up or sticking EGR or leaking hoses or inlet plenum.
None of these will generate a fault code, because they don't involve a closed loop electronic part.
A spinning but underspeed turbo is not going to last long. It'll make a noise and be pretty obvious. Leeking hoses won't happen unless a dodgy mechanic has been playing, and the hiss when you get Mrs to push the loud pedal while you stand at the front should make that obvious too.
The Air filter is bloody hard to get at, but Renault reckon they last 20,000 miles. Hmm.
The EGR is the most likely culprit then. It should be closed or open. Closed when de-powered.
Mine? Well it's under warranty and the Dealer said it was sticking but fine when cleaned.
Note: I'd removed it and cleaned it myself last week. It moved freely, but the outer of the two valves was about 1/2mm off it's seat when the inner one was fully seated. I know it was seated, because petrol wouldn't flow through it. They're on the same shaft so clearly the outer one is out of adjustment. Which is why I booked it in.
The Dealer Foreman doesn't want to speak to me as he thinks I'm full'o'shite as I keep asking questions he can't answer. He reckons it's fine. it must be as it doesn't generate a fault code.....
Ian, sorry for hyjacking your thread for a moment, but we appear to share at least the same model car, and my fresh experience sounds relevant enough.
What I don't know, is where the air goes that comes out of the end valve in the EGR. anyone?