Clattery when cold
Join Date: Feb 2012
Location: United Kingdom
County: Greater London
Not really. The EGR exists to reduce engine efficiency and hence combustion temperatures and NOX creation. Swirl flaps exist to mix exhaust gas and fresh air so that EGR works better. EGR and swirl are interrelated here, a NOX reduction system that increases CO emission. A good idea if it worked reliably, but it doesn't. The mixing of soot and oil mist from the turbo and breather gradually deposits gum on the inside of the inlet manifold that chokes the engine. The swirl flaps leak as their bearings wear and jam and get turned into permanent obstructions by the build-up of gum. Instead of 2 inlet valves per cylinder effectively you have 1.something, boost leaks, incorrect injection amounts and poor AFR. And that's just on the metal manifold with plastic flaps. The later plasti manifold has stainless steel flaps that break off and enter the cylinder. Valve, head, piston damage are the usual result. It can be worse, wrecking the bore and or turbo.
I've just been through that, though my bores and turbo escaped. I've deleted the EGR and swirl flaps and cleaned a layer of gum out of the manifold. Autolusso mapped out the blanked EGR. It's now brilliant with no loss of power, and more importantly no probability of disaster. Yes NOX will be a bit higher and I wish it wasn't. If AR care to come up with a design that works reliably I'll gladly fit it. But the EGR-swirl valve mechanism is at best a recipe for problems and lousy performance that isn't even slightly green, and at worst a premature write-off of an otherwise decent car and a ton of new pollution manufacturing a new one.