Bad Mileage - Need help??

[mfivvibe]

Hi Guys, recently I realised my mileage is getting less than before and slightly lost power at the low end. I have replace my Iridium plugs but same result.Secondly, my idling is now reading at 800rpm or slightly higher even after 10 mins warm up every morning. Is it normal?FYI, i have not make any mod on my engine since I bought 2 years ago except replace a performance filter on the 1st year. Is there any possiblities that dirty MAF cause this problem. Really need help.. Petrol is very expensive and I travel 60 KM per day. Sigh..$$$$

[MrRich]

What was your mileage and what is now? And when did it dropped?Just to start here.

[mfivvibe]

My original mileage is about 480KM - 500KM. But now I can achieved max 400km, if I'm lucky 420km. This happen after my odometer shown 60000Km. Thanks in advance.

[goodvibe]

I was going to blame winter gas but I see that you're in Singapore. If you get winter formulations, they can have a 10% negetive mileage effect. Try cleaning the MAF if your performance filter is a oiled gauze type. Even though dirty MAFs ussually run lean, the ECU may have learned something inapropriate or the timing could be retarded. Use some fuel cleaner. Techron or Redline work well. Do 2 consecutive cleaning and then change yur oil. You'll at least know that those aren't your problems if the mileage doesn't improve. People tend clean to often and use too much oil on gauze drop-in filters that give a max of 1% hp gain and can screw up the MAF. Don't clean the filter with the MAF.

[joatmon]

I average my mileage over several tanks, one individual tank can give you really good or really bad numbers. Start (if you don't already) keeping track of how many litres it takes to fill up, and how many kms between fillups. Judging from how many kms a tank will go doesn't include the number of litres it took to fill up again after those kms.In viewtopic.php?f=17&t=6088&#p65128, there is an excerpt from the service manual on what to check if lower than expected, or lower than it used to be.

[BlueCrush]

Quote, originally posted by mfivvibe »Hi Guys, recently I realised my mileage is getting less than before and slightly lost power at the low end. I have replace my Iridium plugs but same result.Secondly, my idling is now reading at 800rpm or slightly higher even after 10 mins warm up every morning. Is it normal?FYI, i have not make any mod on my engine since I bought 2 years ago except replace a performance filter on the 1st year. Is there any possiblities that dirty MAF cause this problem. Really need help.. Petrol is very expensive and I travel 60 KM per day. Sigh..$$$$Mine idles at 750-800rpm when warm so that is normal.I would first check the air filter (either clean it or replace it).See how your mileage is with that change first.Then make sure nothing crawled up into the intake tube between where the air enters the intake tube and the air box.If that doesn't help then check and clean the MAF.Also, if your defroster is on in the winter your will lose lower end power as well. Because when using the defroster the A/C comressor is running. So, check that as well.If it has been cold in your area your mileage will decrease in general due to warming up the car before driving. However, in cold weather there generally is a an increase in power due to the colder more dense air entering the intake. Good luck and let us know your results.

[damronjr]

I never really used to keep track of my mileage back when my Vibe was stock, but at this point I average about 15-16mpg! Since I started watching it I have always averaged about the same, usually a little less than 200mi per tank when I fill it up. 800rpms seems about right for a normal idle.

[mfivvibe]

Thanks everyone for your input. I guess with all the tips, I should be able to find out the cause soon. Anyway, while surfing the net I saw this useful KB, for your reading pleasure...

Attached files K&NStatement.pdf (17.1 KB) 

[mfivvibe]

Another piece.. about MAF

Attached files cleanmaf.pdf (144.2 KB) 

[joatmon]

There is also mistamtrix's MAF cleaning how-toSome people say to be sure to disconnect the battery before messing with the MAF

[BlueCrush]

Quote, originally posted by joatmon »Some people say to be sure to disconnect the battery before messing with the MAFYES! Definitely disconnect the battery before removing the MAF. It is very easy to fry it.

[damronjr]

Quote, originally posted by joatmon »Some people say to be sure to disconnect the battery before messing with the MAFI think it's just a safety measure so you don't accidentally fry it or sort it out.

[MrRich]

Quote, originally posted by mfivvibe »My original mileage is about 480KM - 500KM. But now I can achieved max 400km, if I'm lucky 420km. This happen after my odometer shown 60000Km. Thanks in advance. Do you have a GT or a base Vibe?

[joatmon]

based on http://forums.genvibe.com/zero...41862 and http://forums.genvibe.com/zero...53416 , I'd say he has a base (1ZZ) Voltz

[goodvibe]

That K&N statement is double talk. The MAF can't work properly with oil on it but you can't know if it's defective until it's clean. K&N then says it's often damaged from cleaning thereby relinquishing any responsability. A brand new drop-in can coat the MAF and cause problems that have been documented here before but the oil shouldn't be a problem if cleaned carefully.

[chrisp]

Id have a look at the O2 sensor Thats where the engine gets its info . Additives can damage as well as age, This is a bit soon at 60K k. Cut your warmup . Its waste of energy. Check your tire pressure also. These things all add up. Good luck.