Leaderboard

Hi my fault forgot to put the 1 in front of the 21,500, I will let you know as soon as I come up with a suitable catch tank as some I have viewed have an immediate design flaw as there is a vent on top to relieve pressure/fumes but are a primitive design and will also allow air in after the MAF which will cause no end of problems as its just like having a built in air leak which will promote excessive regenerations thus knackering the DPF in record time, I wish both our engines were as simple as the A4 but unfortunately the SCR system is a whole new ball game, you have to do the research before indulging in any mods to the existing system, just been looking for them on the net. My engine is a CNHA but believe me they are very similar with only subtle differences. Steve. Steve.

Hi the term Audi use is reducing agent, it is actually adblue and the term is derived from the system our cars use which is Selective Catalytic Reduction, the system works thus, you will have three sensors before the cat one is an exhaust gas temp sensor the other is an oxygen sensor the last one is a Nox sensor of which there are two, the correct designation are upstream for before cat and downstream post cat, before all of these is what is basically a small captive shower head which when commanded by the ECU will spray adblue into the exhaust stream pre the first bank of sensors, the first NOX sensor registers the amount of Nox in the stream and the second registers the particles after the adblue spray and depending on its in formation log may request more adblue, the whole mixture is then fed into the DPF which does its thing with the soot particle entrapment, here lies the problem to make the exhaust cleaner still there is an EGR cooler at the back of the DPF which is attached to another EGR valve which when opened by the ECU at low speeds sucks the already treated exhaust gas through the cooler with drastically cools the gas to so when it is reintroduced in to the engine to be re burnt by the combustion cycle it won't be to hot which reduces combustion temps and burns any Nox 1 that escaped the first time, as I said the main culprit for the blockages is the PCV system as this adds extra engine oil vapour and water vapour neither of which burn very efficiently if at all. thats why Audi recommend longer faster journeys as at higher speeds both EGR valves are shut as the engine needs as much oxygen rich air as it can get to maintain the speed therefore it burns slightly hotter and burns off a lot of the accumulation from town/city driving. Steve.

Good luck on the trip Jack and look forward to reading the instalments