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Poor fuel economy?.? Is it due to MAF sensor issue?

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mathurageethan
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Poor fuel economy?.? Is it due to MAF sensor issue?

Postby mathurageethan » Thu Dec 11, 2014 3:41 pm

I am new to this site. I have an Altezza for six months. It is RS 200, black top, Dual VVT i. YOM 2000. Once I purchased the Tezza, I did a full tune up. However, the fuel economy is poor. It is doing 5.7km/l. That is 17litre/100km. I am daily driving in traffic (Colombo, Srilanka). I hope my MAF sensor is the problem. I have given a MAF clean too. Now I wm driving with the MAF disconnected just to assess. Do I have to replace MAF sensor? Is there an easy way to check the MAF? Is the a MAP sensor(Manifold absolute pressure sensor) in Altezza? Can it be a problem? My emmision test is excellent. Then Oxygen sensors should be alright? Any expert help please.

Soiled
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Re: Poor fuel economy?.? Is it due to MAF sensor issue?

Postby Soiled » Thu Dec 11, 2014 9:30 pm

I'm surprised it drives with the MAF disconnected, it will not prove anything by doing it.

No map sensor.

And what fuel are you running? Running poor fuel can lead to terrible economy as the computer detects knock it'll retard the timing.

What was done in the 'full tune up'? Spark plugs? Engine oil (what grade oil) and filter? Fuel filter?

After cleaning the MAF did you do an Ecu reset?

Checked tyre pressures?

Checked that all wheels are spinning freely so that none of the brakes are seized on? Wheel bearings?

How bad is the traffic? I'm guessing it's not idle for hours type bad traffic where you'd expect poor economy?

Sorry about having no answers but the questions might help you look in the right place. Even on a bad day my altezza (stock) would get 10km/l so yours definitely is using more than it should.

mathurageethan
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Re: Poor fuel economy?.? Is it due to MAF sensor issue?

Postby mathurageethan » Sun Dec 14, 2014 5:44 pm

Thank you Soiled. In the tune up, I have changed all oils with engine oil Mobil fully synthetic 5W-30. Oil, fuel and AC filters, All spark plugs with Iridium IK 20, timing belt and drive belts and bearings. MAF sensor, throttle body and fuel injector were cleaned. Wheel alignment and balancing were performed. Tyre pressure is 32 with Nitrogen. Fuel is Octane 95. One of my friend told me that, if we drive MAF disconnected we can have an idea. If there is no change in performance the MAF is not functioning and if it is improving the MAF is malfunctioning like. Traffic also heavy in Colombo. I am not too heavy foot in throttle. Now I hqve planned to change a new MAF. I have purchased one Original OEM Denso MAF sensor from ebay from a US seller. This costed me a USD 150. Because I am too suspicious on MAF. Coz, it is 14 years old and my mechanic did not use the proper MAF sensor cleaner. I do not know what he has used. I heared, it may go wrong with the improper cleaning too. It s better to change. Do I have ti reset the ECU once I change the new MAF? How can I reset?

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RS Tom-Hundred
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Re: Poor fuel economy?.? Is it due to MAF sensor issue?

Postby RS Tom-Hundred » Mon Dec 15, 2014 12:55 pm

mathurageethan wrote: Fuel is Octane 95.


Think that could be the key to it (possibly) as Ive heard that these engines run bad and low on power (and probably economy) if not on end end fuel of high octane. I run mine on 99 octane and get very decent economy.

mathurageethan
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Re: Poor fuel economy?.? Is it due to MAF sensor issue?

Postby mathurageethan » Mon Dec 15, 2014 1:08 pm

Think that could be the key to it (possibly) as Ive heard that these engines run bad and low on power (and probably economy) if not on end end fuel of high octane. I run mine on 99 octane and get very decent economy.[/quote]
Hi Tom. That could be a pissible reason. However, there is no Octane 99 in Srilanka. Our market has only 92 and 95. Even for the 95 my economy is poor I think. I hope changing the MAF will give me a good result. I will update once I change the MAF. Thank you Tom.

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chewse
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Re: Poor fuel economy?.? Is it due to MAF sensor issue?

Postby chewse » Tue Dec 16, 2014 5:56 pm

the octane of my fuel is the same as yours 91-95 and i get between 470-510km from full to low fuel light

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mlcoolj
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Re: Poor fuel economy?.? Is it due to MAF sensor issue?

Postby mlcoolj » Tue Dec 23, 2014 8:57 am

if it says 95 octane at the pump it doesn't mean it's actually 95 octane, at least over here in Holland it's like that.. eg 98 over here is not 98 at every pump.
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