What is fault code 2003 on a mitsubitsi colt 3000i

I got this free Pdf manual from reliable-store for free and I don't think Ive visited a mechanic or fixya for help for more than 3-4 times out of the 20 times I fixed the chipper in these 4 years

try an online search for Mitsubishi trition same years

What device is the error code coming up on? (It's impossible to help without this information!)

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no
fuel line size will not affect fuel consumption
the major item that has an affect on consumption is the fuel pressure in the fuel manifold for the injectors
next is the heated and normal oxygen sensors because if they are out of parameters the ECM will pour the fuel through the engine
next is a blocked cat converter
best advice is to run the fault codes to find out what is happening

Fuel consumption figures usually don't mean very much as there are lots of variables affecting consumption in the real world.

The EEC force manufacturers to state consumption figures for cars sold in Europe. One or two of those are results from constant speed tests but the third is called the urban cycle which is a realistic real-world figure but don't forget the Imperial gallon is bigger than the US gallon so it is probably better to stick to litres.

Few motoring journalists have a vehicle long enough to produce useful consumption figures and simply recycle each other's information. A few journalists test a car for a week or longer and do produce their own useful figures.

When searching for reliable information it is important to know what sort of driving, the type of country, the ambient temperature and so forth as hot or cold weather can affect consumption significantly so any figures you find are fairly useless without qualifying information.

have you checked the engine computer for trouble codes ?

V6 colt bakkie big ends bearing torque settings

maybe its an axle the axle will make it shake