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1997 GTI6 110k faied MOT today on emissions. Just fitted all new exhaust and CAT,genuine lambda,temperature sender,oil change fuel filter change. washed and oiled cone filter,injector cleaner, blew through crankcase breather pipes in case they were blocked,new spark plugs. It does not smoke when I rev it hard but it is awful on fuel. 200 to a tank. Any ideas before I Sorn it and buy a car cover. Would a bottle of petrol treatment and a good thrash help?
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CAT,lambda,or temperature sender is fecked
check the fuse for the lambda heater
get it on diagnostic software and live read the sensors to see what is happening
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Pattern CAT? the Euro car parts one are cheap for a reason
Overall Road Going Production Class Winner at BARC Gurston Down Speed Hillclimb 2012, 2013 & 2014 With a class record along the way (For a while), Taking 2nd place will be Ian Redding's 306 GTi
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Like Cully said, need to get it on some diagnostics to give some indication of what's going on. Unfortunately when it comes to mixture regulation you don't always get specific codes that point to one thing. If you haven't been getting at least an intermittent engine check light I'd be surprised.
Could be one of the new parts (lambda & coolant temp sensor) are still the problem if you haven't fitted good quality parts. (Learnt from experience there!!!).
OR, could be MAP or air intake temp sensors, which also input to mixture regulation. Previous cat was prob damaged by over-rich running. (On mine it was burnt thro n half the cat internals ended up in the back box!).
OR, could be loom supplying any number of sensors.
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Just spoke to the 306 guys in Thetford. Apparently non genuine green temperature senders can read wrong and cause over fuelling. Also check the fuel pump relay on the back of the battery box is not cracked or missing its top. That will screw up the mixture if water gets in. Mine is fine unfortunately.
