I've been battling a bit of low gas mileage and have been documenting my mileage over the past few months to prepare for this thread.

303.7 miles / 15.824 gallons = 19.19 miles/gallon
278.1 miles / 16.132 gallons = 17.3 miles/gallon
277.0 miles / 15.677 gallons = 17.7 miles/gallon
270.0 miles / 15.384 gallons = 17.5 miles/gallon
257.4 miles / 14.902 gallons = 17.27 miles/gallon

The first reading is a little higher due to 140 miles of that being one continuous highway drive. I've seen several threads that mention over retarded timing being a common cause. I have an ELM module that I'm going to use tomorrow morning to start documenting my timing with the Torque app as I drive around.

What other things should I be looking at/measuring? MAF? Fuel ratio? I don't currently have any codes and all my O2 sensors are Bosch replacements that are no more than 1.5 years old.

Any help is much appreciated.

 

When I had my 97 and 03 Maxima I never got the fuel numbers in the high 20's that everyone here was boasting about, I normally got 19 or 20 and occasionally 21.


I even used 91 or higher octane gas too. What I would suggest is that you check your air filter, spark plugs, and add some injector cleaner to your next 2 or 3 tanks of gas.


Currently in my 2010 Maxima I average 20 to 21 mpg's and I find myself putting gas in my car at least 2x's a week because I like my car to be full all the time.


I don't complain about gas prices because I just moved back from California in June and I was paying $3.90 to $4.30 a gallon out there now I'm paying $2.58 to $2.71.

 

^+1 on checking the plugs, air filter, prem gas. Also check tire pressure. Techron Concentrate is a good cleaner since it works on the entire fuel system, not just injectors. A lot of people say gas is gas but I definitely get better mileage from "Top Tier" stations like BP and Exxon. On long trips, I can get up to 26 mpg with the A/C running. City driving slaughters my mileage; I'm lucky to get 17.

 

I always blame maf

that or O2 sensors

 

I've noticed . From what I understand diagnosing a bad MAF isn't terribly easy. Any tips?

A few things I should have noted earlier...

• I never use anything other than premium gas (Here in CA we get 91 octane)
• I replaced all the spark plugs around 60k miles ago when I started having misfire problems. At the time I wasn't aware of the coil issue.
• The first mpg I listed was run with a can of BG44K.

I'll try out that Techron concentrate in my next few tanks. I need to fill up in the next few days anyhow.

 

If I notice MPG decrease I just swap it out. They're free at junkyards You can carry several out.

 

I agree with this. I don't think anyone driving an 02-03 is getting high 20'mpg. Maybe on their trip computer it's saying that and they believe it but I don't think they're getting that in reality. Unless you're driving all highway miles at grand mom speeds but even then highly doubtful.

 

3.5 with stick ALL HWY should yield high 20s up to 80 mph and then increasing while 70 and under. If you were to do 60 you'd have stupidly good economy. If you have hills or a strong headwind, then of course mpg will suffer. I'm sure auto will only see high 20s at 70 and under.

Driving hard with a lot of city should net mid teens. It's quite easy to get low 20s avg (half and half) even with spirited bursts.

DE-K auto does pretty damn good. I got 24 mpg driving through the Appalachians (all of VA and WV) at 80-85. In the low hills in Ohio I got 28 at the same speed.
I left all the 4 bangers in the dust in the mountains LOL. It was really sad watching them crawl up. Not once did it shift out of OD.

 

I've been checking my timing with an ELM and the Torque app. From what I read in the FSM the acceptable timing in D at idle is 15°(+/-5°). In P I sit right at 15°. When I shift to D my timing drops to 10°. Still within the acceptable range but right on the hairy edge. I have seen it drop to 9° on occasion sitting at idle.

Anyone else with a 4AT and an ELM know what their timing is at idle?