MarkM Posted January 20, 2023 Report Share Posted January 20, 2023 Hello Everyone, I'm new on here. I've had a VW 1.4 AHW Lupo for a few years now. Approx 140K miles. Every year it struggles to get through Emissions on the MOT. I've tried everything. The car has had a brand new cat, lamda sensor, map sensor, spark plugs, spark plug leads, coil pack, injectors, throttle body, air filter , oil and filter. I've calibrated the throttle body and bought VCDS Ross tech which gives no information on fuel trim? Unless I'm not using the software correctly. Two questions for you guys is , what is causing these high emissions? CO is 0.59 % ( pass is 0.30) HC is 258 ppm ( pass is 200). Also why cant I find long and short fuel trim in the VCDS software. The car Is 'k' line OBD not OBD2can-bus. Any help before I swap the engine? Mark 🙂 Quote Link to comment Share on other sites More sharing options...
mk2 Posted January 20, 2023 Report Share Posted January 20, 2023 Tried blocking off sump blow by fumes (or diverting down under the car)? How about temp sensor swap? That's a common reason for odd emissions. I'm assuming it doesn't use any oil over 5k miles. The numbers tell us that too many hydrocarbons are going into the engine. So high CO and a fair bit of unburnt fuel coming out. Running rich. Quote Link to comment Share on other sites More sharing options...
scotty2 Posted February 4, 2023 Report Share Posted February 4, 2023 Copied from my thread as relevant: Well, progress on the emissions front since putting in and testing the new temperature sensor. Put the car on the exhaust analyser and getting high CO. but Lambda and HC within limits. 150 on HC but still high on CO. Will fit new cat next week and re-test next week. Change temp sensor and check it before digging deeper... Quote Link to comment Share on other sites More sharing options...
mk2 Posted February 4, 2023 Report Share Posted February 4, 2023 I don't think the cat swap will be a permanent fix. May work for a week or so until choked. I still think that it's overfuelling (running rich) for some reason. Things usually affecting mixture are coolant temp sensor, MAP or MAF sensor, altitude compensation, fuel pressure regulator, evap canister solenoid, fuel and air filter and finally fuel pump. Those are for steady state running. For sudden/transition enrichment, throttle position sensor and MAP sensor. All assuming no mechanical problems, leaks or contamination. Quote Link to comment Share on other sites More sharing options...
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