Why is my MPG so poor?
11-25-2014, 05:56 PM
#1
Why is my MPG so poor?
Hello,
I just filled my 2002 Nissan Maxima SE gas tank and I took a receipt and wrote the mileage as I've been doing for a few months now, but today I had the curiosity and I finally calculated the MPG from a few random gas receipts including today's, and the results were shocking and terrible. The results were averaging 9.5 mpg in city use... I couldn't believe it, so I went online and searched the mpg for this car which should be 17 City Mpg. What is going on?!!!
A few information you might want to know:
-My Car has a 15 inch subwoofer in a 4cu ft mdf enclosure and two big AGM batteries in the trunk.
-I always use Premium Gasoline.
-I have new filters, spark plugs, oil, coils, proper inflated tires, etc...
-My daily commute(90% of my car normal week use) is: 9-10 City miles total roundtrip(Non to Moderate traffic on one way) with 15 mins avg of start idle time daily, various traffic lights and the Maximum speed is 30 mph.
-95% of the time I accelerate very smoothly.
-No Check Engine light.
Let me know If you need to know something else that will help detect problem.
-Why am I getting such low mpg?, What can I do?
Thank you
I just filled my 2002 Nissan Maxima SE gas tank and I took a receipt and wrote the mileage as I've been doing for a few months now, but today I had the curiosity and I finally calculated the MPG from a few random gas receipts including today's, and the results were shocking and terrible. The results were averaging 9.5 mpg in city use... I couldn't believe it, so I went online and searched the mpg for this car which should be 17 City Mpg. What is going on?!!!
A few information you might want to know:
-My Car has a 15 inch subwoofer in a 4cu ft mdf enclosure and two big AGM batteries in the trunk.
-I always use Premium Gasoline.
-I have new filters, spark plugs, oil, coils, proper inflated tires, etc...
-My daily commute(90% of my car normal week use) is: 9-10 City miles total roundtrip(Non to Moderate traffic on one way) with 15 mins avg of start idle time daily, various traffic lights and the Maximum speed is 30 mph.
-95% of the time I accelerate very smoothly.
-No Check Engine light.
Let me know If you need to know something else that will help detect problem.
-Why am I getting such low mpg?, What can I do?
Thank you
Last edited by argenis69; 11-25-2014 at 06:16 PM.
11-25-2014, 06:07 PM
#3
It could be oxygen sensors or fuel injectors. But nothing I can think off that could make your gas mileage that terrible. My guess is that you calculated your mpg wrong. I assume you did it right, but just in case, you take the amount of miles you've driven since you last filled up with gas (gas filled all the way) and divide that by the amount of gallons you pumped into your car this time you filled up with gas (gas filled up all the way). I'm guessing maybe you divided by the price and not the number of gallons?
11-25-2014, 06:13 PM
#5
First post Updated.
What I did was erased the trip miles last time I filled up, I empty the tank today and filled up. Wrote down the trip miles and divided it by the gallons the car took today. I believe that's correctly, right?
What I did was erased the trip miles last time I filled up, I empty the tank today and filled up. Wrote down the trip miles and divided it by the gallons the car took today. I believe that's correctly, right?
Last edited by argenis69; 11-25-2014 at 06:16 PM.
11-25-2014, 06:17 PM
#6
11-25-2014, 06:24 PM
#7
11-25-2014, 09:24 PM
#11
Yes, that's correct. Makes more sense than the mumbo jumbo you said in the first post. So, how many gallons did you put in today, and how many miles were on your trip odometer?
11-25-2014, 09:57 PM
#12
Its because you're idling for 15 minutes. Thats a long time that you're getting 0 mpg. That combined with only 10 miles round trip means you spend more time idling than actually driving to/from work.
Start it up, wait maybe 30 seconds, and go.
Start it up, wait maybe 30 seconds, and go.
11-25-2014, 10:31 PM
#13
Unless he's stopping every 1,000 feet, then low speed is even better. When rolling at 30 I'm going to get well over 30 mpg.
That's why I say MAF is old/dirty.
Last edited by Child_uv_KoRn; 11-25-2014 at 10:40 PM.
11-26-2014, 02:39 AM
#14
11-26-2014, 03:34 AM
#15
next time you fill up, record exactly how many gallons you put. once its time to fill up again. divide the amount of miles driven on your odometer by the amount of gallons your car took from the first fill (obviously) and you should get pretty much the exact mpg
http://mpg-calculator.com/
Last edited by bumpypickle; 11-26-2014 at 03:39 AM.
11-26-2014, 04:34 AM
#16
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
^ That is some terrible mpg. You would really benefit from a scan tool and looking at some live data.
But things I can think of would be O2 sensors, MAF, fuel injectors, cats, etc...too many possibilities really. Get a cheap scanner and do some diagnostics IMO
But things I can think of would be O2 sensors, MAF, fuel injectors, cats, etc...too many possibilities really. Get a cheap scanner and do some diagnostics IMO
11-26-2014, 07:45 AM
#17
So, when I connect the obd scanner I can test/diagnose each part for failure even if the check engine light is off?
11-26-2014, 07:46 AM
#18
Well, it's cold up here and I like to get into my car warm
11-26-2014, 09:45 AM
#19
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
You can get yourself a wifi obd2 adapter and one of the few android apps (car guage pro or torque) and for a total of bout 20 bucks.
You can look at data of your fuel trims, o2 sensors, maf readings, fuel injectors, etc...live data so you can see what looks wrong and it helps you go in the right direction to diagnose. You can also check for codes and reset the light now or in future. Just a great tool to have in general.
You can look at data of your fuel trims, o2 sensors, maf readings, fuel injectors, etc...live data so you can see what looks wrong and it helps you go in the right direction to diagnose. You can also check for codes and reset the light now or in future. Just a great tool to have in general.
11-26-2014, 10:06 AM
#20
You can get yourself a wifi obd2 adapter and one of the few android apps (car guage pro or torque) and for a total of bout 20 bucks.
You can look at data of your fuel trims, o2 sensors, maf readings, fuel injectors, etc...live data so you can see what looks wrong and it helps you go in the right direction to diagnose. You can also check for codes and reset the light now or in future. Just a great tool to have in general.
You can look at data of your fuel trims, o2 sensors, maf readings, fuel injectors, etc...live data so you can see what looks wrong and it helps you go in the right direction to diagnose. You can also check for codes and reset the light now or in future. Just a great tool to have in general.
11-26-2014, 10:14 AM
#21
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
For wifi adapter ebay or amazon, anywhere will have it. You need an Elm327 or newer adapter. Plug that in, connect to car...good to go
11-26-2014, 11:19 AM
#22
11-26-2014, 01:05 PM
#25
11-26-2014, 01:48 PM
#28
Do you have a copy of the Factory Service Manual (FSM)? If not, click the link in my signature to get a free copy. In there, it will tell you what the live data should look like for each respective part..MAF, O2 sensor etc.
Do you have a Digital Volt Ohm Meter (DVOM)? Do you know how to use it and check resistance etc?
Besides failing O2 sensors, injectors and MAF, I'd consider the following too
Brakes-maybe you have a stuck caliper that is adding a lot of resistance
Fuel leak
Exhaust leak or exhaust restriction
Here's a quick link for tips to increase gas mileage
https://maxima.org/forums/general-ma...ge-thread.html
Do you have a Digital Volt Ohm Meter (DVOM)? Do you know how to use it and check resistance etc?
Besides failing O2 sensors, injectors and MAF, I'd consider the following too
Brakes-maybe you have a stuck caliper that is adding a lot of resistance
Fuel leak
Exhaust leak or exhaust restriction
Here's a quick link for tips to increase gas mileage
https://maxima.org/forums/general-ma...ge-thread.html
11-26-2014, 03:59 PM
#30
Do you have a copy of the Factory Service Manual (FSM)? If not, click the link in my signature to get a free copy. In there, it will tell you what the live data should look like for each respective part..MAF, O2 sensor etc.
Do you have a Digital Volt Ohm Meter (DVOM)? Do you know how to use it and check resistance etc?
Besides failing O2 sensors, injectors and MAF, I'd consider the following too
Brakes-maybe you have a stuck caliper that is adding a lot of resistance
Fuel leak
Exhaust leak or exhaust restriction
Here's a quick link for tips to increase gas mileage
https://maxima.org/forums/general-ma...ge-thread.html
Do you have a Digital Volt Ohm Meter (DVOM)? Do you know how to use it and check resistance etc?
Besides failing O2 sensors, injectors and MAF, I'd consider the following too
Brakes-maybe you have a stuck caliper that is adding a lot of resistance
Fuel leak
Exhaust leak or exhaust restriction
Here's a quick link for tips to increase gas mileage
https://maxima.org/forums/general-ma...ge-thread.html
11-26-2014, 07:16 PM
#31
Supporting Maxima.org Member
iTrader: (15)
Join Date: Oct 2003
Location: Indianapolis, IN
Posts: 744
It is also possible that water made its way into your parking brake line. When engaged the water could freeze and prevent the line from disengaging. This happened to me, had it replaced.
Checking this is easy. Noticeable brake pad smell, rims are warm or hot, and if you are willing to touch your caliper/rotor, those would be unnaturally hot.
11-27-2014, 04:46 AM
#33
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
For me its been ~17mpg when its cold in winter time, all city. And ~20mpg city during the warm months.
I get somewhere around 25-26mpg highway and like 22mpg in mixed driving during the warm months. Basically winter mpg goes down by ~3mpg for me.
I get somewhere around 25-26mpg highway and like 22mpg in mixed driving during the warm months. Basically winter mpg goes down by ~3mpg for me.
Last edited by D.Stillwell; 11-27-2014 at 04:48 AM.
11-27-2014, 05:59 AM
#34
fuel mileage
My 2002 Maxima SE (116,000) with the ffing modification
Ghetto airbox
NWP vias block plate
gutted precat with Cattman y pipe 2.5 inches
Cattman exhaust catback (3 inches)
Replaced the ffing : OEM Genuine Nissan parts
Knock sensor, camshaft sensor, crankshaft sensor and two primary 02 sensor
City:17 mpg Hwy:19-22
Ghetto airbox
NWP vias block plate
gutted precat with Cattman y pipe 2.5 inches
Cattman exhaust catback (3 inches)
Replaced the ffing : OEM Genuine Nissan parts
Knock sensor, camshaft sensor, crankshaft sensor and two primary 02 sensor
City:17 mpg Hwy:19-22
11-27-2014, 06:22 AM
#35
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
^^ Im still running original o2's and knock sensor, crank sensors all that. Original fuel injectors original fuel pump and filter...
I got 100k miles coming up, probably do at least some new o2's in there, will likely see even better mpg then..
I got 100k miles coming up, probably do at least some new o2's in there, will likely see even better mpg then..
11-27-2014, 07:45 AM
#36
11-27-2014, 08:59 AM
#38
11-27-2014, 09:49 AM
#40
Senior Member
Join Date: Oct 2012
Location: Portland, Oregon
Posts: 2,979
I'm have a fourth generation 1996.
Your mileage should increase noticeably when you change the spark plugs and especially the upstream oxygen sensors. I bet your air filter is dirty. Change it.
You are using the car in city traffic. That is not good for mileage.
Fifteen. minutes of warm up kills mileage. It will also wear out your engine and contaminate your oil.your mileage will increase right away if you would stop doing that. Engines warm up quickly when you drive them.
You asking why your mileage sucks ? Lack of maintenance, city driving, and fifteen minutes of warmup DUH.
Your mileage should increase noticeably when you change the spark plugs and especially the upstream oxygen sensors. I bet your air filter is dirty. Change it.
You are using the car in city traffic. That is not good for mileage.
Fifteen. minutes of warm up kills mileage. It will also wear out your engine and contaminate your oil.your mileage will increase right away if you would stop doing that. Engines warm up quickly when you drive them.
You asking why your mileage sucks ? Lack of maintenance, city driving, and fifteen minutes of warmup DUH.
