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Discussion Starter · #1 ·
Having checked some more, it seems that I get the black exhaust smoke irrespective of whether I'm running on petrol or LPG. I don't seem to have been using masses of oil. Haven't needed to top up in 10k miles.

Sin of sins! I haven't had the car serviced for 10,000 miles.

The engine has done about 140,000 miles, 50k of which has been on gas - which is typically a clean fuel, but some reports indicate the higher combustion temperatures might do some damage. The DI cartridge is under 20k miles old.

Ther "check engine" light has been on for a while, but since its normally always on when I'm running on gas, I hadn't paid attention to it. I've tried using some injector cleaner and running on petrol for a while and that's when I noticed that the light is staying on. The injector cleaner hasn't made any difference, but I've only done 100 or so miles since adding it.

So, to my mind, its likely to be

Plugs (oh, I hope so)
Piston rings
Valves

I'm due to have it serviced on Wednesday, but in the meantime any thoughts on this, anyone?
 

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Black smoke indicates you're running too rich and are chucking out unburnt carbon, so you could have either an AMM or a Lambda problem... however since the Lambda sensor is "last in the loop" I'd suspect that first. Pulling the fault codes will help diagnosis.
 

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Discussion Starter · #3 ·
The gas and petrol systems have different, independent Lambda sensors.

Ther garage should be able to pull up the error codes, we'll see what they say
 
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