fuel economy 1.8gdi

[paulchucky]

dont seem to do much to the gallon ?
ie:£20 = 80 miles

i drive normally 45mph- 55mph gentle pull aways no thrashing or racing from lights
anyone help as to any obvious problems ?

theres no fuel leaks anywhere no air leaks etc


cheers paul

[billofdurham]

The 1.8GDI is noted for its high fuel consumption, noisy tappets and being totally the wrong engine for a Volvo.

It is a Mitsubishi engine which was designed to run on low/zero sulphur fuel, which is mandatory in Japan, and a lot of redesign had to be done to the engine and the catalytic converter to enable it to run on European fuel. This why you are advised to run any GDI engine on a 97 octane low sulphur fuel such as BP Ultimate. The sulphur content blocks up the injectors which is why fuels that contain cleaning agents are recommended.

However, this is not all. The main problem is how the fuel gets into the cylinders. GDI = Gasoline Direct Injection. The fuel is directly injected into the cylinders and does not go through the inlet tract. Only air goes throught the inlet tract and valves and this is where the problem lies - no amount of fuel line cleaners will do any good as they don't go into the inlet tract. Modern engines rely on EGR valves to recycle exhaust and crankcase gases, which include oil mist, back into the inlet tract. On a normal engine this presents no problem as the fuel air mix combines with this and does not allow any great build up of carbon on the back of the inlet valves or throttle body. In the GDI engine as there is no fuel going through the inlet tract all the rubbish from the EGR valve builds up as carbon deposits in the throttle body and on the back of the inlet valves causing problems with poor running /idling and engine management lights coming on.

Depending on how severe the problem is you may need a decoke and a remanufactured throttle body and then run on premium fuel using the recommended synthetic oil. It may not be necessary to remove the cylinder head, a very expensive job. It may suffice to remove the inlet manifold and soak the inlet valves with a chemical carbon remover which will remove a lot of the deposits.

As this engine was designed to run on low sulphur fuels and the compromises Mitsubishi had to make to get it to run on European fuels led it to be significantly inferior in performance and efficiency to the Japanese counterparts.

It may be of no comfort whatsoever to learn that the VW/Audi FSI engines suffer the same problems.

Bill.

[paulchucky]

thanks bill
very imformative looks like ive abit of decoking to do cheers

ps: do you happen to know a farmer selling an old massey ferguson (then i could run it on cherry !!!!!!!!) lol

[hhhugues]

hey i feel i bit better about the consumption on my t4 now ! i manage about the same on £20...