Bad gas millage - Chevy Malibu Forum: Chevrolet Malibu Forums

markanthony404 · 11-08-2012, 06:19 PM

2005 Chevy classic, 2.2 same as the older Malibu. 80k miles. Been having a gas mileage problem, I used to get 24 city/30+ highway. Now I do mostly city driving and I am only getting 15.4 MPG. The car is very well maintained, I have never had a check engine light, oil has been changed every 3 to 4k miles. The spark plugs were changed at 60 K miles. The transmission fluid was just changed last month and I just bought brand-new tires, tire pressure has always been kept at around 32 pounds. The only thing I could think that might be causing this would be a clogged fuel filter, any other ideas would really help. Thanks

cp-the-nerd · 11-08-2012, 07:59 PM

You seem to have covered your bases, that's good. Find someone to check the car's computer to see if it's throwing codes. It should be throwing one if there's a 10 mpg loss in FE.

If you live in or around Baltimore, MD, I'd be happy to help.

markanthony404 · 11-09-2012, 01:03 PM

OK thanks I will try that. I was wrong, I did have a check engine light a few months ago. I took it too autozone and they said it came up evap leak, I think it was my gas cap. I replaced it because the cap stopped clicking and the light hasn't came on since. The only other thing I can think of would be the fuel filter or o2 sensors but if they are bad I would think the check engine light would come on.

cp-the-nerd · 11-10-2012, 06:50 AM

Have you tried fuel injector cleaner? The car seems like it has some miles and you didn't mention the brand or grade of gasoline you buy. Build up can occur over time and possibly effect FE. Someone I know was getting poor mileage from a similarly aged Ford Focus and this helped by 2-4 mpg. I believe he used SeaFoam brand gas additive. There are many videos and tutorials online to walk you through the process.

markanthony404 · 11-10-2012, 11:17 PM

Yes, I always buy fuel injector cleaner with every oil change. I normally just run 87 octane at either sheetz or BP. I have used seafoam before but not in this car. Honestly I don't think it did any good, maybe a little improvement in the cars idle. At this point I'm willing to try anything, i could use it in 1000 miles before my next oil change.

03goldbu · 11-11-2012, 10:15 AM

I usually get around 24-28 MPG in my '03 Malibu with the 3.1 V6.

markanthony404 · 11-11-2012, 11:08 AM

I hear ya, I used to get 24+city/30+ on the highway. I have lost around 9 mpg so there is definitely something wrong. I might have the car looked at by GM next week.

cp-the-nerd · 11-12-2012, 03:29 PM

You might also want to check your air intake box and filter. Make sure nothing's nested in there or badly clogging the air filter. I wouldn't expect that to be the culprit of over 30% fuel economy loss, but it's something that can be inspected in 10 minutes before taking it to the shop.

I don't think the fuel filter will be the problem because restricting gas flow wouldn't make the engine burn MORE fuel and run less efficiently. It would probably just run like crap.

markanthony404 · 11-12-2012, 11:23 PM

Now that you mention that I took the intake apart about a month ago when I change the transmission fluid, this was so I could access the fill cap. I remember there was a plastic gasket that broke in half, this piece was in between the bottom pieces of the intake where it sucks up air from the bottom. I didn't think anything of it but maybe that's what's causing this. I'm not sure the dealer will sell that part.