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Discussion Starter #1
So.. my 75 just failed it's MOT test with high Carbon Monoxide emissions.. time to get diagnosing! I'm going to start by checking the plugs out looking for a stuck injector ( cos it's easy), check the fuel delivery pressure isn't too high... any other ideas? I haven't been to get the car back yet so i've not seen the actual numbers. OBVIOUSLY, it failed on a load of other bits too :D but nothing that needs diagnosing. Any bright ideas welcome!
 

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Burning oil will drive up CO emissions.
Valve stem seals and/or guides, or worn out piston rings and bores.
 

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Discussion Starter #3
Yeah, I'm kind of ruling that out for the minute, as I dont lose any oil at all and never any hint of smoke, so I'm going to look for the culprit in the fuel delivery system
 

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Is your car the version with the O2 sensor, or without? High CO readings usually indicate a rich mixture. If the problem is at idle, I think there is an adjustment screw for the cars without an O2 sensor.

If the car uses an O2 sensor, I think a faulty sensor or sensor connection could cause the mixture to go rich.

If you had an excessively rich mixture, or bad ignition, you would also be seeing excess HC readings. If only the CO readings are elevated, I think it is probably not due to ignition, and the mixture is only slightly rich.
 

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Discussion Starter #5
So.. got the car back and got the emissions analysis to read, turns out they tested it as a cat equipped V6:eek: Nice to know that you are handing your pride and joy over to professionals! Someones getting a little phone call in the morning!

DPBERNER: It is non cat, no O2 sensor
 

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Oops! Well, overall that's good news, I guess. Sounds like you will be in the clear once the proper pass/fail boundaries are applied.

It's frustrating when someone screws up like that, but better than having something wrong with the car.
 

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Discussion Starter #7
Yeah, hopefully, Still not 100% on what the correct limits are, which is why I need to speak to the garage, so its not impossible that is may still be a fail, but I'm inclined to think it will pass
 

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Discussion Starter #8
*Update*

Now all passed! Still pretty annoyed about it but at least we're back on the road!
 

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Discussion Starter #10
Nope! It passed fine on the right test it actually wasn't that far off the cat limits
 
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