Quote:
Originally Posted by C.Doner
high CO and HC at the same time usually points to excess fuel. Not just a rich mixture. You could have vacuum leaks as well which will lean the system out. If your ECU compensates for the lean mixture with more fuel you get high emissions all over the place. The first place after the tune up parts to be positive about, is the vacuum system. Make sure all vacuum hoses are in order. Then from there look at the fuel injection. Make sure all injectors are working properly. Start with the simple things then move on to complex parts.
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With reference to this ^^^^
I'm not sure if this will be a wild goose chase (or not) but I was reading about tuning my M102 engine and there was a bit in the FSM about disconnecting the fuel tank vent from the system when checking idle speed and the behaviour of the fuel injection system. My M102 (for emissions) has a carbon filter system for the fuel tank that eventually leads to the air intake - essentially after a bit of cocking about the nasty vapours from the fuel tank end up going into the air intake. This can raise the idle and make the mixture too rich.
I wouldn't be surprised if that was also the case for the OP's car - this is just one way in which a mixture might end up with excess fuel.