Poor Gas Mileage

**PogiGreg** · 06-05-2008, 09:16 PM

I've been getting poor gas mileage lately. This last time, I went 252 miles only. My average was 17mpg. I did a search for poor gas mileage and came across a few threads that I will explore. One of which was the the O2 sensor. Is there a specific brand that I should buy? Should it be genuine Mitsubishi or does it matter? The fuel filter could also be a culprit. I have a new one ready to go in at my next fill up. I also read one post where one guy changed the distributor. What about that? That one I doubt because I replaced the entire engine with an engine with 118,000 miles. Any ideas?

**pinoyesv6** · 06-05-2008, 09:22 PM

before u start buying random parts here and there, are u up to date with good ole regular maintenance with your car?

**guynlidia2006** · 06-05-2008, 09:22 PM

replace fuel filter, air filter, do a 3 step fuel system cleaner, check your tires are at the correct air pressure, is your check engine light on for the o2 sensor? if so replace it with a direct fit denso o2 sensor. But remember u have 2 o2 sensors... so make sure u replace the right one. Also if the alignment is out it can cause extra drag thus lowering your gas mileage... That woud be my professional opinion....

**DOHCstunr** · 06-05-2008, 09:29 PM

Odd that no one has mentioned spark plugs, wires, cap and rotor.

Here's the deal, if you haven't updated any of the forementioned items, you'll have poor gas mileage and worse, poor performance.

So get to work, document your mileage and see if things are improved.

**guynlidia2006** · 06-05-2008, 09:33 PM

lol , i thought he recently replaced the motor... so i was thinking simple... but at least plugs and wires would help probally

**PogiGreg** · 06-05-2008, 09:46 PM

As you know, this is a replacement engine in my Galant. This new engine has only been in for less than 6 months. I have new plugs and wires, but not new cap. I did also lower the car with Sprint springs, took it to get aligned, and they only made toe adjustments. My rear left camber is -2.3 degrees and my rear right is -2.8 degrees. Could that be a factor as well?

**guynlidia2006** · 06-05-2008, 09:53 PM

naw... just waste tires... but take care of the other things then redo the average

**Galant306m** · 06-05-2008, 10:20 PM

Check your gas cap to make sure that it isnt leaking.! If the fuel tank isnt getting pressurized you will get crappy gas mileage.

**PogiGreg** · 06-05-2008, 10:40 PM

Originally Posted by Galant306m

Check your gas cap to make sure that it isnt leaking.! If the fuel tank isnt getting pressurized you will get crappy gas mileage.

No gas leaking from the gas cap. Not quite sure how to check for pressurization though.

**G-spot** · 06-05-2008, 10:47 PM

fuel pump?

**RafalGTZ00** · 06-06-2008, 07:23 AM

See how expensive it is for a tune up at a local mitsubishi dealer.....

**PogiGreg** · 06-12-2008, 08:04 PM

Found out today why I'm getting poor mileage. After changing the oil, transmission filter, and changed my fuel filter. I took it to my mechanic, and I trust this guy, he hasn't steered me wrong ever. When I first told him about it, he first thought based on my description of the problems, it was a clogged up cat. After test driving it, he concluded that the torque converter is engaging intermittantly. Sometimes it does, and sometimes it doesent. Bassically it wasn't transferring power to the transmission, and the engine had plenty of power. I am thinking of doing a full flush which gets the fluid out of the torque converter. If not, now is the time for me to put a better torque converter in. What would be an ideal one to get?