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Over fuelling

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I am currently running a 90 with an auto box and 3.9 efi engine from a disco.

I changed the resistor (thanks RPI) about 12mths ago and the engine ran well however the engine running has recently become very lumpy. I have cleaned the dizzy and cleaned the HT leads (magnecor) and checked that they run as separately as possibly inc king lead, I have also changed the plugs.

Judging by the smell of petrol and state of the plugs (black) I am guessing that the engine is running very rich. This presumably would contribute to the lumpy running.

How do you stop the engine from running so rich? And is there anything else I should be checking re the lumpy running.

Thanks in advance.

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Sounds like the water temperature sensor for the EFI is faulty ……. Very common fault. In fact so common that I carry a spare in the cubby box :rolleyes: !

The ECU then thinks the engine is continually cold and issues the appropriate amount of fuel command to the injectors.

You can check it, by measuring the resistance of the sensor with the engine cold and then again with the engine at running temperature, but to be honest its just as easy to change it ;) .

The replacement sensor is fairly cheap ……. About £11.

Its located behind the dizzy toward the left hand side of the engine (viewed from the drivers seat – bank 1 – 7). The sensor has a blue top …….


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