Posted this on G35 forums, but perhaps someone here could also shed some some light..

Yes you read it correctly, currently Im getting about 9mpg. Realized this awhile back and started monitoring my fuel consumption a bit more closely. After several fillups Ive varied between 166miles and 212miles from full to low fuel light. I am a spirited driver at times, but the majority is just normal driving.

Vehicle is '05 5AT Sedan

Fuel is always 93

Only mods on the car are:

MD 5/16 spacer
Stillen 'Hi Flow' intake
Stillen catback

ANY thoughts or insight?

 

Too much audio in your car. You can give me some of your audio so that you can lighten your load of the car.

 

Time to drive the Honda more! Clean/change air filter...perhaps fuel filter?

 

any codes ? dead o2 ? tire pressure too low ? fat girlfriend ? (just kidding REALLY)

EDIT: parking break cable not releasing or seazied caliper slowing u down-- 9mpg is too low to be a simple filter or spark plug, sounds like something major is affecting ur engine

 

have any MAF related problems that would make that an option?

 

that is insane, i would check the accuracy of the odometer.
cant be anything small

 

does the amount of gas ur putting in correspond to the size of ur tank? possible fuel line leak?might only be obvious when the car is started

 

Now we both know that wont happen.

 

I try to. Air filter is good and the fuel filter should be as well. My car just lapped 9k miles.

 

No CEL and I checked for codes anyway -nothing came up. Tire pressue is dead on. Unsure of o2, but is it that common? No fat chicks.

P brake cable is definately fully released and I did the brakes not too long ago. All is good there. Performance overall seems normal, but could use a bit more umph.

 

I have no other problems aside from the mpg issue. Unfortunately a new MAF is just too expensive to 'try out' without anything definitive leading me to it.

 

Everything there seems to be in order.

 

Yes it does. Even if the car sits for a bit, gas is still there whether driven or not.

 

have you done a V-12 swap anytime recently and just forgot that you did it? 9mpg? that's frickin insane.

I suspect it's a fuel leak. But if you were REALLY running that rich, check your plugs and see what they look like. But damn, 9mpg? you sure some punk isn't siphoning your gas? lol

 

Hmmm ok, this is getting more and more strange, did this happen overnight? or it gradually began to eat more fuel ?

assuming the gauges are fine (the trip meter AND the fuel tank gauge) i cannot come up with a single issue that could be causing this.

are there ANY problems with the car? anytihng at all

 

LoL

Wouldnt I spell a fuel leak though? Also wouldnt it set off a CEL?

 

I just happen to notice one day and started monitoring it.

As far as I know they are.

Nothing else seems wrong. Although as stated about the car could use a bit more umph, but that may be me being used to it and bored. Theres a *very slight* sputtering idle, but been there for quite some time.

 

It's all in your head, the G35 is an engineering marvel, nothing can go wrong with it.

 

now That is all in Your head.

 

I'm inclined to agree with Gone...

 

you can rev to redline right? thats all i was asking with the MAF cause if you can it rules out the MAF. wouldnt be a fuel leak because you wouldnt get enough pressure when the car is running. almost has to be a rich problem, you dont smell rotten eggs when you drive do you?

 

Do you always fuel up at the same station?

 

Oh then yes I can rev fine. No funky odors at all.

 

No, various ones in the area. Thought about that as well though.

 

Try to take off the MAF and clean it out with MAF spray cleaner. Might be too much oil contaminated from the Stillen intake cone filter. No codes for O2 sensor, camshaft sensor, knock sensor, etc? Drop a bottle of Chevron fuel injector cleaner for a tank full of gas and monitor problem.

 

I have a bandwagon that would disagree with you

You are going about this the wrong way. The solution is to add more air, not use less fuel

 

Where would I find specific MAF spray cleaner? No codes for anything. Honestly wish there was so I can start from somewhere. I have the injector cleaner, actually went with the Lucas this time from some recommendations. Although I am used to the Chevron..

 

CRC MAF cleaner. Got mine at Kragen/Checker.

 

I have a 92 Maxima SE.. It's killing me in gas! I've changed plugs, all six coils, was told to change the fuel filter,, not sure why if it's using too much fuel but did it anyways,, Had a number of mech's tell me it's not the o2 sensor MAF is good and EGR is good but still only get around 13 to 15 mpg. That's down from 27 mpg not more than a month ago. It started out 1st and 2nd was a little sluggish and now it just lays down on me when I give any pedal at all in any gear.. It just runs rough and shaky and it doesn't matter if it's a cold start or if I've been running all day. Sometimes after sitting for 30 minutes it runs right for maybe 30 miles then lays down on me again. I've pulled cables and reset the computer but give it 2 miles and it starts again but the check engine light has never came on. I've put more into this car than I paid for it and still haven't figured it out. If you get yours figured out send me some advise. I know yours is a lot newer but at this point I'd try anything!!!

 

I wouldn't clean the maf if you have the warranty still. That's when you raise hell with the dealer. I doubt the maf would cause that kind of MPG, ecu preset maps have to be better than that. How's the oil level?

 

Definately still under warranty. I had a problem in the past when the injen intake was in there and they claimed it was due to the location of the MAF on the intake. In that problem I was actually running lean and pulling codes of banks 1 & 2. After confirmation from a good friend of mine at the local dealer that they werent feeding me crap I swapped the intake to the Stillen and the problem quickly went away.

Oil level is normal and clean. Although I have been considering swapping all fluids to the Purple stuff, but that may be a whole nother topic.

 

Those are not helping you keep the finely tuned G35 motor running at top efficiently. O2 sensors will absolutely cause poor gas mileage, even if they are working and not giving any error codes. Same goes for the MAF. If you can find a shop with an exhaust gas analyzer, measure the hydrocarbons to see if your running to rich. If so, change the front O2's.

 

Im assuming the stealership would have such tools? Im going down there tomorrow evening for some stuff and could have them check that. This is after hours, so it's not a normal scheduled appointment. Is there anything else specifically that I should have checked?

 

Everyone knows 05's had stock wb o2's right? Any datalogging software will tell you how rich you are. Uprev comes to mind.

 

Never assume.

 

Ahhh then do You have em? OR..where else would I go?

 

It was well worth a try.

 

Find a local guy w/ OBDII scan software, hook it up, see AFR, profit?