Hi everyone, So I am new to owning a S3 8l fantastic car when it works! Now this is whats happening, I have seemed to get a good grip on the symptoms and believe me this is a interesting one! I will be following this thread to the end posting a cure too, too many threads never conclude! Stock Engine Brand new fuel filter Brand new original MAF Replaced coolant temp sensor - green cap Replaced Lambda Replaced Fuel Pressure regulator IK22 plugs Replaced Air temp sensor on plenum Opened and examined EGR module no loose connections or broken solders. Wiring checked over cam cover, some splits found and insulated Any broken connectors like coil packs were replaced Nothing is really bodged at all Throttle body was re-adapted (VCDS adaption) checked out OK, just incase it had been fiddled with I ran the adapts Throttle body has been cleaned Seems to become more prominent in slow traffic and idle situations recently, almost as if its fouling plugs that bad during low RPM running, it take a good open pedal moment to clear it out and even then it struggles to pick revs smoothly and quickly, whatever is causing this causes the engine to really bog down and is definitely unburnt fuel I am a test and development engineer so I will be able to support this well, I am just new to the 1.8t Someone has to have felt this before? Before I got GT871r I need to resolve this issue Important but not the cause - I am told the car was flashed, I am working on acquiring some software to read this but I am happy with the MAP, the car ran brilliant when I bought it, it ran even better when I fixed minor leaks on the PCV system. MAP sensor and Thermostat have not been replaced, this is tomorrows job. The fault is intermittent, or its there all the time and only more noticeable at certain times. The fault appears in idle - no load Cruising low RPM under boost conditions and also in no boost conditions (idle) The car runs so rich the plugs become fouled like charcoal, when its in this mode for a few mins and I touch the accelerator the floor is then laiden with a jet stream of carbon from the exhaust, almost as if the fuel is washing the carbon out. When this fault comes in the car feels surgy and out of power, a definite lack of efficient combustion resulting in what would normally feel like a misfire, you could argue it is a misfire but not the normal coil pack or plug, he fault is definitely in and out, at times the car shifts like a rocket no black smoke at all, at other times I can see the clouds pumping out behind me. I seem to be able to turn the problem on by blipping the accelerator pedal a few times, on idle the black smoke coming out of the exhaust can be observed as well as black spits of carbon on my hand if I was to briefly put it near the exit flute of the tips. Vac system has been deleted entirely, Fuel pressure regulator runs to inlet manifold Dump valve (Forge) run to manifold The third larger union on the bottom of the middle of the plenum has been simply blocked. The head and crank vent to atmosphere The car ran sweet so I know its a new issue, not one there from previous hands being in it, well not that I have found so far anyway. On VCDS when I could borrow a set of leads I had no faults, initially I had a few faults due to disconnecting N75 and MAF while running trying to figure it out, ones codes were cleared nothing re appeared, the car was scanned a week later using a snap on modus, no new faults. Hitting a brick wall here!! Affects all four plugs, no difference in them they are completely blacked, there is no beige on these what so ever, they look no different to coal. The carbon build up on the tips is ridiculous and the poor MPG speaks for itself, Something is making my S3 over fuel like crazy and I just can find the fault please help!! Thanks Hiren Questions: Anyone had a faulty MAP sensor do this? I don't have a boost gauge on it yet, or anything to monitor the MAP values at the moment so stuck there too...Ross tech is brilliant but pricey, what are my alternative CAN comms options? Ebay VCDS leads? any recommended links? Thermostat - I have come across some instances on forums of thermostats causing running rich issues, I know the TT allows a check via the AC panel has the S3 got such functionality? This one s driving round the bend seriously! I am very competent and will be able to support and anwser any questions. All the sanity checks have been done but ask me your questions give me your thoughts I must get to the bottom of this one!