SpoiledGT

Thanks for that Smaky thought it might have been overfuelling and maybe harming the cats. Never known an exhaust to get so sooty though I have to clean it off twice a week.

Forgot to mention I've already cleaned up the 2 large electrical connection blocks at the rear of engine bay plus all 4 lambda and maf connectors. I've looked at output graphs for lambdas & maf sensors and all look normal apart from slightly slow response from post cat bank 1 sensor.

Hi all first post here and have a few niggles which I hope someone here can help with. I've had my 2004 gt jts since November 2014 and the mpg has always been low..about 20 around town and 30ish on motorway runs. I was getting a few error codes(1131, 1151, 1175 and 0303) at first and since then I've repaired a split intake hose, replaced maf, had oil and filter change, changed coil pack on cylinder 3 and all sparks and had a new exhaust flexipipe and back box fitted but although i've solved almost all mcsfs I'm still getting the poor mpg as well as sooty exhaust. The oil has also gone dark very quickly too. The car has had a full service history and 51,000 miles on the clock. I have been taking it on a motorway runs every couple of weeks to clear the cobwebs and it does drive fine with no flat spots etc. The 0303 code does pop up when cold starting every so often but the mcsf self clears and it runs fine. Is there any reason for these niggles or are they just traits of the jts engine?