I own a 2004 g35 coupe, 5AT. Complete stock car, no mods at all yet, and all tires are 30 psi. It has 98,000 miles on it. I use 93 octane gas( BP Ultimate with that invigorate stuff ). My gas milage is terrible, around 10 MPG. What can i do to check/fix my MPG?

p.s. it costs 45 bucks a week to fill her up and I dont drive hard at all :|

 

You certainly have a problem. I would start by changing my oil, air filter, and fuel filter. If that doesn't increase the mileage, i'd start checking plugs and injectors. 10mpg is crazy.

 

Thank you I was thinking about doing the whole works soon. There must be something wrong that I can just change instead of the actual car.

 

Oh yeah it should definitely be fixable. It sounds like a combination of dirty filters and/or oil.

 

+1 on the filters and oil.

Let me know if you need any of those parts. I can have them shipped off to you today!

 

hmm MT always use less gas, AT uses more gas? that is fact, i guess

 

30 PSI? That's a little low.... although that's certainly not going to be the sole contributing factor to you getting such extremely bad gas mileage as you are.

The recommended pressure is 35 PSI.

Is your Check Engine Light on?

Give us some info about the cars history..... did you buy it new? How long has it been having such poor fuel economy?

I've seen situations in the past where a person buys a car from a shady used car dealer, and the car had a problem that was causing the Check Engine Light to be on, and the dealer would just smash the bulb in the dashboard for the Check Engine Light, so a buyer wouldn't know there was a problem with the car. That actually happened to my dad when he bought some old piece-o-junk used GMC Sonoma a few years ago.

 

check your tire pressures. I have an 07 with 19s and it calls for 35lb of pressure. Its just a thought.

 

Sorry Partyman66 just read your post lol.

 

Consider cleaning you throttle body and O2 sensor. These are largely ignored when looking at mpg and even some power gains. When cleaning the throttle body, be careful that you use a cleaner that won't damage the sensor, otherwise you can worsen a problem or create one where none existed.

With respect to the sensor, have it checked or check it yourself to see (sometimes codes won't register it as bad) if it's "switching" correctly. I believe it's a Bosch planar type (not sure, does anyone know this??), so readings could be tricky since it may use newer "wide band" technology. >50% of newer cars now use these b/c of their efficiency and effects on mpg, emissions, power, etc.

I've done everything others have suggested above, plus this and a few other things (e.g., run Sea Foam thru my vacuum line and gas tank), and average about 450 miles per tank with 40% city/60% highway in somewhat rough (potholes, bad roads, very steep inclines) terrain.

Good luck and I hope this helps
Isa

 

45 dollars to fill her up?
i had a similar issue but it had something to due with my gas tank , dont remember what but it would say i had a full tank but it only filled up 3/4 of the way, took it to the dealership and the said that my gas guage inside the tank was off

 

yep 30 is a bit low try 35. Hows your air filter?

 

Can you share how you're calculating 10 m.p.g.? I hate to ask this, but we've seen time and time again fuel economy calculations being done incorrectly.

 

I just double checked my Tire and Loading Information on my car and it states the recommended is 30 PSI. I can take a picture to show you.

Nope no engine lights at all, I have yet to see one yet

I just bought it over a month ago from a 1 owner old person. He babyed the hell out of it so it seems like he treated it well.

Over 2 weeks the MPG is just been terrible and being 17 my job isnt paying enough for my gas :\

Thats a scary story right there that would be the worst for me. But nothing at all. Everything is stock in the car and in tip top shape as far as im concerned.

 

Im assuming to clean those sensors, you use Seafoam? My next oil change is in 500 miles and I was already planning on seafoaming my car.

My driving is basically 60% city, 40% highway. Mostly smooth roads.