159 Cruiser and
AO Silver Member
Join Date: Jul 2012
Location: United Kingdom
EGR & DPF advice
EGR: exhaust gas recirculation. In order to reduce NOx emissions regulations, one way of achieving this is to reduce the temperature of the burn in the cylinder. Car makers realised this could be done by reducing increasing the CO2 in te cylinder. They found they could do this by pumping exhaust gas back into the engine, so it gets taken from just before the turbo, and put back in the manifold (just before the cylinder vavles).
As you can imagine there is a lot of soot going into the manifold, this mixes with oily air (look up oil catch can). The basics of this is the whole manifold gets filled with gunk, cause endless issues ( swirl valve failures, reduced air flow, reduced response etc). The extra CO2 also reduces the cars performance in every respect ( let alone after time).
The EGR valve is also poorly designed and when filled with gunk , it jams open, so you can't stop the CO2 going in the engine, giving major issues.
The EGR can be cleaned (1hr job) or replaced (£80 on eBay for parts or £300+ done at a dealers). See the 'power loss guide' in the stickies.
The DPF is a ceramic filter in the exhaust. It is designed to capture the diesel soot ( the EGR also increases soot production), unfortunately you have to get rid of this collection of soot, so every 4-700miles ( or set number of hours), the engine literally throws diesel down the exhaust to burn it off!
This clearly increases fuel use (but is designed to run without being noticed), however with time, it is harder and harder to clean ( they have a life of around 80,000miles+), clearly this is affected being your driving (short journeys) or if the car has had other issues ( increase in smoke). Obviously expensive to replace), and increases fuel consumption, and drop in performance ( noticeable when they get blocked)
Many people will delete or blank this to improve drive ability, performance and reliability.
The Giullieta has improved the design of both the EGR ( has a built in cooler, and different mechanism), and DPF (closer to the engine, thus running hotter and making regens more effective), but these are really reliability improvements, the cooler also means the EGR going into the engine is cooler, helping performance too
Any spelling/ grammatical errors are purely there to annoy!
159 1.9JTDM Ti and Giulietta 2.0 Veloce
ex: Punto 55s, Golf Mk5 1.4FSi, A3 (8P) Sportback 2.0TDi SE, A4 (B8) 2.0TDI S-Line, 306 HDI Meridian