Euangti Posted April 11 Report Share Posted April 11 Hello everyone, this forum has been a godsend on so many issues with my car but I’m looking for advice on my Lupo failing its emissions again. last year it failed on the first test but after a new air filter, some pre MOT liquid and a good high rev run it passed, just. this year I did all those things before the MOT but there was no way it was passing, the lambda reading was 1.331 and wouldn’t go any lower. the tester thought it might need a new cat as the car has 245k km. the other thing is that the car is constantly running at low temp, around 70 degrees when going at any speed over 50ish. Around town it goes up to 90 degrees as it should. I’ve changed the temp sensor and coolant, it’s also just had the belt and water pump done, could this be related? It uses a bit more fuel than it should I reckon, although it doesn’t burn an excessive amount of oil and the exhaust isn’t smoky. I noticed the crankshaft breather pipe was in really bad condition with some big cracks so I’ve ordered a new one of those but I don’t think that’s what’s causing my problems. there are no lights on the dash, very occasionally when the weather is cold the EML light will come on but it goes away after restarting the car. Any help would be greatly appreciated as I’m a bit lost and don’t want to pay for a whole new cat if that’s not the problem. cheers Quote Link to comment Share on other sites More sharing options...
mk2 Posted April 11 Report Share Posted April 11 Thermostat? Quote Link to comment Share on other sites More sharing options...
Euangti Posted April 11 Author Report Share Posted April 11 Do you reckon that should be the next port of call? If it’s stuck open (which I assume to be the case) then the engine would run rich and lead to higher emissions and fuel use? 1 Quote Link to comment Share on other sites More sharing options...
mk2 Posted April 11 Report Share Posted April 11 Yes it is possible. The new coolant temp sensor also might be faulty. There are many that fail. You need to use diagnostics "live data" to check. 1 Quote Link to comment Share on other sites More sharing options...
Euangti Posted April 11 Author Report Share Posted April 11 I went on a little run this afternoon with an obd reader plugged in and the live data temperatures seemed to correspond to the temp displayed on the gauge. That would indicate that the temp sensor is working correctly but the thermostat is not, is that correct?? thanks for your help so far! Quote Link to comment Share on other sites More sharing options...
mk2 Posted April 11 Report Share Posted April 11 Yeah. Also check it when cold to see if it reads about 20 or whatever your average overnight temperature is. Quote Link to comment Share on other sites More sharing options...
Rich Posted April 11 Report Share Posted April 11 I struggled and fitted new lambdas and it cleaned them right up even though it didn't register a fault. Quote Link to comment Share on other sites More sharing options...
Euangti Posted April 12 Author Report Share Posted April 12 Okay thanks mk2 I’ll check that this morning! Yesterday I looked at the voltage readings for the lambdas and the post cat one appeared to have correct voltages, it was fluctuating between 0.15 and 0.6. But the pre cat was on 1.35 and just stayed there, didn’t fluctuate at all despite driving up and down hills and accelerating/decelerating. This would suggest a problem with it, no? I’ve ordered a new one to see how it gets on Quote Link to comment Share on other sites More sharing options...
Euangti Posted April 12 Author Report Share Posted April 12 I also changed the crankcase breather and pipe as I’d ordered it before it failed the MOT. It didn’t solve the emissions problem but I’m sure it wasn’t helping looking like this 1 Quote Link to comment Share on other sites More sharing options...
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