Each year the ol '44 struggles to get through the MOT on emissions. I am fortunate that the place I take it wants to see it pass, and so always spends a bit of time getting it up to temp, or fiddling with the only control available - the AFM screw. It has been successful again this year, the car was taken for a good 'blast' down the road and then back on the analyser to record a good result. However, I am not happy to leave it at that and want to try and get to the bottom of the higher than normal CO2 readings (the HC is fine). So, I will shortly strip the intake assembly and clean the bypass valve, the throttle body, etc. Check for vac leaks, look at the AFM track and give the AFM a bit of a service. In fact, I have a complete intake assembly from my donor car that I could service, clean and simply fit..that might be easier?
I have noticed that the idle speed does seem to always be a little higher than I would have expected (around 1100, where it should be 800-900), so something is amiss. Generally, the plugs look good, so is there anything else in addition to the above that I should be on the lookout for?
Also, has anyone had experience of the Gunson G4125 Gastester? It looks like it might be able to help while I 'play' and investigate the issue, what do you think???