What's Wrong With My Iq ...

[jpwalker]

my fuel-up goes crazy these few months ..

from Jun to Sep, it drop from 16KM/L to 11KM/L

I try to change the engine oils, gear box oil and oil filter.. but no help

Any possible problem and advice ?

Thanks

[FROSTYBALLS]

Any other symptoms? Eg poor acceleration, etc.

[Sensha]

And, are you in "D", or "S" (if using a CVT)?

[Andy Kay]

Sorry if this is too obvious, but how often do you check your tyre pressures?

[tarquin]

Warmer weather ? My iQ always seems at its peak performance on a colder crisp day and sluggish in the warmer months

David

[jpwalker]

Any other symptoms? Eg poor acceleration, etc.

Yes, poor acceleration

And feeling leak of power

[jpwalker]

And, are you in "D", or "S" (if using a CVT)?

you mean the gear ?

Yes, i always in "D"

[jpwalker]

Sorry if this is too obvious, but how often do you check your tyre pressures?

um... didn't check my tyre pressure for awhile.

but tyre pressure shouldn't affect the fuel consumption such huge ?

I will check it today after work

[jpwalker]

Warmer weather ? My iQ always seems at its peak performance on a colder crisp day and sluggish in the warmer months

David

um.. but my fuel consumption last year is pretty normal

[tarquin]

Increase in passenger carrying?

David

[bobkneale]

My MPG is always better in warm weather, as it has now gone a little cooler in the UK I am back to 60+ MPG when is was hotter a few months ago I got up to 70 MPG+

[FROSTYBALLS]

As yours is an early IQ, and you also have poor acceleration and lack of power, could it be an issue with the EGR valve/? See http://www.toyotaownersclub.com/forums/topic/147454-egr-problem/

[Grumpy Cabbie]

Sorry if this is too obvious, but how often do you check your tyre pressures?

um... didn't check my tyre pressure for awhile.

but tyre pressure shouldn't affect the fuel consumption such huge ?

I will check it today after work

You wanna bet? They do make a significant difference, but as others have said, the sudden and significant drop and the fact you own an early IQ indicates either lack of servicing OR the common EGR problem. Assuming the car is upto date on its servicing, your tyres are at the correct pressure, then EGR sounds probable.

Where in the World are you? What are your journeys like? Do you use cheap supermarket petrol? Lots of short journeys using rubbish petrol could be a cause too. Either have your dealer look at the car or a cheap fix might be to run some 'quality' fuel system cleaner through the car and take it for a run on the motorway.