Wats Wrong With My Mpg?

[Bilal8210]

hey guys, ive just recently noticed that my car has started to drink even more petrol than it allready did! lol i used to get a jus about reasonable 100 miles for twenty quid but now its droped to 80. lol thats even less than 20 mpg i fink. it is just small journeys around town but surely i should be gettin more for my money than this? ive got the 98 avensis gls 1.8. ive chekcked all the oil levels and there fine. neva had any trouble with the car for past 3 years either! the car has dne 69k. any1 got any ideas that could help me?

fanx

realli appreciate the help guyss

[billsinc]

Someone else driving your car. Someone taking petrol out the tank. A petrol leak, should smell that. Chnaged your general driving, busier traffic, colder days, leaving A/C or rear windscreen heater on.computer putting too much petrol through, a temp sensor not working????

[sjrainsford]

Your leanburn Avensis should be getting much better than that, even running around town! Mine never dropped below 35mpg.

Just a hint, but there was a problem on models from around that year with the fuel tanks. Some leaked at the seam where the two halves of the tank were assembled. It may pay to get underneath and have a look at yours. I had the same model as you with this problem. They rust for some reason. The Toyota guy said they'd done quite a few of them.

Otherwise, it will pay to get it checked out - possibly by Toyota. You should never be getting that sort of fuel consumption. Bear in mind, I get more than that out of my 2litre Rav 4 around town!!

Some simple checks you can make yourself:

Make sure all the vacuum hoses in the engine bay are connected correctly with no signs of damage.

Obviously check that the air filter isn't blocked in anyway, and the rest of that associated circuit.

Check that it has the correct spark plugs, they are platinum in these if I remember right.

Make sure someone hasn't disabled the check engine lamp.

[bryanbengal1]

COULD BE DIRTY MASS AIR FLOW METRE LOCATED BETWEEN AIR FILTER AND ENGIN HELD ON BY 2 PHILIPS SCREWS ABOUT THE SIXE OF MATCH BOX

http://www.fordscorpio.co.uk/cleanmaf.htm

ITS FOR FORD BUT WILL SHOW YOU HOW TO SOLVE. THIS IS ALWAYS WORTH DOING ON ANY FUEL INJECTED CAR AS IT TELLS THE SYSTEM HOW MUCH AIR IS GOING IN TO THE ENGINE, AND CHANGES THE MIXTURE ACORDINGLY, RESULTING IN RICH MIXTURE. tHAY ARE NEVER CLEANED DURING SERVICES IN THE LIFE OF A CAR

[Beardie]

20mpg..you have a fuel leak or a fuel thief or a blocked air filter. If it was to use that much in running, you'd notice sluggish performance with the over rich mixture. Are you sure the car's not left idling in traffic for hours on end?

[dazwan]

For £20 I would expect at least 200 miles (I do mostly M'Way driving though) so even before you noticed this drop in economy it sounds like things were never too good. I'd take it to a Garage to have the whole fuel/iginition system looked at.

BTW my Avensis is a 1.8 GS with 100K so I'd expect you to get around the same as me, roughly about £1 for every ten miles. How much do you get out of a full tank on a good day? You should expect in excess of 400miles.

[sjrainsford]

Just to point out, you don't have a Mass air flow sensor.

[tubaman]

??? I thought most recent fuel injected cars had these things ? What does the Toyota use ?

[sjrainsford]

The pre VVTi 1.8 engines, 7A-FE use a combination of a MAP sensor (manifold absolute pressure) which is normally mounted on the bulkhead connected with a vacuum hose to the inlet manifold and an IAT sensor (inlet air temperature) which can normally be found somewhere near the air filter housing or the piping from it.

This is basically what was used before the introduction of MAF sensors and gives a similar result. The IAT sensor does what it says on the tin so the air temperature (therefore density) can be determined and the MAP sensor measures engine load by measuring the amount of positive or negative air pressure in the inlet manifold. The more negative the pressure (or more vacuum) the less load the engine is under.

Sorry if i've made that all sound a little complicated. Only i read back what i've written sometimes and manage to mix myself up!!