getting 9-10 mpg what to do??
03-30-2011, 09:55 AM
#2
#1. Make sure maintenance is up to date
#2. Do you have any codes?
#3. How exactly did you calculate 9-10mpg? Or do you just feel like thats all your getting or did you actually do the math?
#2. Do you have any codes?
#3. How exactly did you calculate 9-10mpg? Or do you just feel like thats all your getting or did you actually do the math?
Last edited by Shift_Nismo; 03-30-2011 at 11:31 AM.
03-30-2011, 10:27 AM
#3
03-30-2011, 11:51 AM
#5
Pull over because you have a gas leak! If the car is still running smooth then the only thing I can think of that would cause that low of mileage are flat tires, ore else one or more of your brake calipers are frozen. Are any of your wheels hot after you drive?
03-30-2011, 01:27 PM
#10
You sir have a serious problem, check for leaks asap.
03-30-2011, 02:20 PM
#13
03-30-2011, 02:20 PM
#14
03-30-2011, 06:34 PM
#17
wouldn't you smell the gas if you had a leak?
wouldn't you be able to feel the breaks grabbing @ real low speeds and smell them once they heated up @ high speeds?
if the o2 sensors were bad there would definitely be some codes.
your tires would need to be basically flat for you to get that low of mileage and you would notice.
did you just notice a drop in mileage or has it been slowly decreasing?
if i had to guess i would say its probably a combination of a lot of things.. ive red a few times on here about people getting poor mileage if they went way over 3k miles for an oil change. so maybe its a combination of low tire pressure, "clogged" air filter, old spark plugs, crappy 87 octane gas, busted o2 sensors, and driving style.
wouldn't you be able to feel the breaks grabbing @ real low speeds and smell them once they heated up @ high speeds?
if the o2 sensors were bad there would definitely be some codes.
your tires would need to be basically flat for you to get that low of mileage and you would notice.
did you just notice a drop in mileage or has it been slowly decreasing?
if i had to guess i would say its probably a combination of a lot of things.. ive red a few times on here about people getting poor mileage if they went way over 3k miles for an oil change. so maybe its a combination of low tire pressure, "clogged" air filter, old spark plugs, crappy 87 octane gas, busted o2 sensors, and driving style.
Last edited by ThreePointO; 03-30-2011 at 06:39 PM.
03-31-2011, 01:04 AM
#18
And on my 4th gen, I had 2/3 out (just not connected) car still ran fine (sort of, it's problems weren't O2 sensor related at the time, had other issues which is why the sesnsors were disconnected).
03-31-2011, 06:19 AM
#20
Just basing off of my personal expierience, I took my 5th gen home w/ 3 bad O2 sensors, still got 27-28mpg on from Atlanta -> Houston.
And on my 4th gen, I had 2/3 out (just not connected) car still ran fine (sort of, it's problems weren't O2 sensor related at the time, had other issues which is why the sesnsors were disconnected).
And on my 4th gen, I had 2/3 out (just not connected) car still ran fine (sort of, it's problems weren't O2 sensor related at the time, had other issues which is why the sesnsors were disconnected).
With this set-up, my highway driving is great, 28 MPG.
But my city driving is horrid because of the open loop/closed loop switchover which occurs at low load, aka city driving and i get 17MPG. It is also noted on my WB when I'm in low load situations, low throttle (don't quote the FSM word for word, throttle position to RPM relation, because it is still a general range/value, as eng92 has proven this quantitatively and I have observed it qualitatively via my WB) my car runs pig rich when in low load situations.
Also, with all that said my car is a cali-spec (03, as they all are). But the vehicle in question is a fed spec, meaning less O2 sensors, and therefore more chance for said sensors to be faulty (less sensors = less back-up choices for ECU to rely on, good example is my set-up where the 2 secondaries make-up for the lack of primaries on the highway).
I've also noted some cars, when all O2 sensors d/c'd will dip in the 10's AFR-wise.
But, with all that said, it may also be a MAF issue, typically placement, vs fault.
03-31-2011, 09:11 AM
#21
My primaries are disconnected but my secondaries are plugged into the primary port.
With this set-up, my highway driving is great, 28 MPG.
But my city driving is horrid because of the open loop/closed loop switchover which occurs at low load, aka city driving and i get 17MPG. It is also noted on my WB when I'm in low load situations, low throttle (don't quote the FSM word for word, throttle position to RPM relation, because it is still a general range/value, as eng92 has proven this quantitatively and I have observed it qualitatively via my WB) my car runs pig rich when in low load situations.
Also, with all that said my car is a cali-spec (03, as they all are). But the vehicle in question is a fed spec, meaning less O2 sensors, and therefore more chance for said sensors to be faulty (less sensors = less back-up choices for ECU to rely on, good example is my set-up where the 2 secondaries make-up for the lack of primaries on the highway).
I've also noted some cars, when all O2 sensors d/c'd will dip in the 10's AFR-wise.
But, with all that said, it may also be a MAF issue, typically placement, vs fault.
With this set-up, my highway driving is great, 28 MPG.
But my city driving is horrid because of the open loop/closed loop switchover which occurs at low load, aka city driving and i get 17MPG. It is also noted on my WB when I'm in low load situations, low throttle (don't quote the FSM word for word, throttle position to RPM relation, because it is still a general range/value, as eng92 has proven this quantitatively and I have observed it qualitatively via my WB) my car runs pig rich when in low load situations.
Also, with all that said my car is a cali-spec (03, as they all are). But the vehicle in question is a fed spec, meaning less O2 sensors, and therefore more chance for said sensors to be faulty (less sensors = less back-up choices for ECU to rely on, good example is my set-up where the 2 secondaries make-up for the lack of primaries on the highway).
I've also noted some cars, when all O2 sensors d/c'd will dip in the 10's AFR-wise.
But, with all that said, it may also be a MAF issue, typically placement, vs fault.
04-04-2011, 10:49 PM
#24
In Re to the O2 sensor comment.
I just got a codes for all 3 o2's on my roadtrip, still got 34-36mpg, I stand by my original comment, O2 sesnors are useless for MPG reasons.
And City mpg was still around 30, didn't do enough city driving (Manhattan, KS is toooo small)
I just got a codes for all 3 o2's on my roadtrip, still got 34-36mpg, I stand by my original comment, O2 sesnors are useless for MPG reasons.
And City mpg was still around 30, didn't do enough city driving (Manhattan, KS is toooo small)
04-04-2011, 11:49 PM
#25
Pick up your Haynes Manual and look in the troubleshooting section for poor gas mileage and see what it lists. O2 sensors will be one of the possible culprits.
Pick up your FSM and go the codes for O2 sensors. I believe gas mileage is mentioned there too.
Also, how are you getting 34-36mpg when a 5spd Max is rated 22 city/27 freeway and the auto is rated 21/28?? That has to be a typo...
04-05-2011, 01:48 AM
#26
Member
Join Date: Sep 2003
Posts: 219
To put this into perspective I just drove a rental from the PDX area to SLC (aprox. 800 miles). The truck was a 26' box pulled by a 9.3 turbo diesel international maxforce9 (over 300hp and 900+ lb ft). We had well over the 'limited' 9k on a 30k single axle (26k gvwr)... At any rate my point was, I got 8.36 mpg. That is significant considering what I was pulling and the passes/mileage covered. Are you pulling a boat or something with your maxima?
TBH, if your maxima's engine (if anywhere near stock) was actually consuming enough fuel to equate 9-10 mpg, it would not be running. You got some great suggestions on what to check and gave us the equivalent of a one-word-answer response. I do not understand how you expect to be helped.
BTW - You will not get an accurate number if you test your mileage on only 1 tank of gas. Sure it will get you into the ballpark; assuming you are competent. You should be filling up, then recording mileage and exact gas input over a few 'tanks worth' of driving. For all I know you poured cement into your gas tank and it now only has an 8 gallon capacity. (I think that is about as likely as you getting your claimed 9-10mpg.)
I would like to know: How and where you looked for a fuel leak. What having 'new' brakes quantifies as/to. How you tested your O2 sensors. As well as how you actually tested mpg.
What I really want to know is how people come up with their crazy conclusions... lol
04-05-2011, 06:36 AM
#27
04-05-2011, 07:34 AM
#28
Senior Member
Join Date: Sep 2009
Location: Worcester, MA
Posts: 4,011
!!!
04-05-2011, 08:58 AM
#31
Sorry bud, but that's quit an ignorant comment. Just because your situation doesn't match with what most people experience (worse gas mileage with bad O2's) doesn't mean that what you say is fact.
Pick up your Haynes Manual and look in the troubleshooting section for poor gas mileage and see what it lists. O2 sensors will be one of the possible culprits.
Pick up your FSM and go the codes for O2 sensors. I believe gas mileage is mentioned there too.
Also, how are you getting 34-36mpg when a 5spd Max is rated 22 city/27 freeway and the auto is rated 21/28?? That has to be a typo...
Pick up your Haynes Manual and look in the troubleshooting section for poor gas mileage and see what it lists. O2 sensors will be one of the possible culprits.
Pick up your FSM and go the codes for O2 sensors. I believe gas mileage is mentioned there too.
Also, how are you getting 34-36mpg when a 5spd Max is rated 22 city/27 freeway and the auto is rated 21/28?? That has to be a typo...
98 V6 Camaro
97 LeSabre
04 Mustang LX
02 Mitsu Diamante
-Already Mentioned
01 Maxima
99 Maxima
All of them had 2 or more failed O2s, took all 4 of those cars across country or drove them through houston thousands of miles with the failed o2 sensors, they all got atleast what the EPA said or better MPG. Now, I will re-do my previous statement, since I do not have crazy scientific jargon or fsm quoting to back me up, just personal experience.
From my personal experience bad o2s will NOT affect a car's performance.
I'll grab the Haynes later. And the FSM stuff is at the bottom of my post.
When I was 5MT I got 26 city and 28 highway mpg, even my stock 5th gen got 25 city and 27 highway. The best I ever got out of a 5mt was my current maxima at 37mpg (It's disputed, so we'll say I drove 10hrs on one tank of gas) on the north and southbound Oklahoma City->Manhattan, KS portion of my trip, but that was a freak occurence that has yet to be repeated.
But then Shift_6th thing in my sig isn't a joke... I'm 6spd w/ a 4.1 FD. And on this trip with the 3 o2 codes, PNP and revese light code, I did Manhattan, KS to a gas station to Ennis, TX (my odometer said 551 miles, I did stop in OKC and Denton for a bit too) on less than one tank of gas, the light came on in Ennis, so I just pulled over to get a break and get some gas to get home.
Here's an exhaustive list of what to check via FSM, I only have the 99 one downloaded, but I'm sure it's the same for you....
-Check EVERYTHING that has to do with Air, from Air cleaner to Throttle Body, then make sure your Idle is correct (Make sure it's within spec 550-750)
-Make sure your TPS is working and Adjusted
-Check your MAF
-Check the Engine Coolant Temp Sensor
-Check the Injectors (Says check the wiring? I'd also make sure a few of them aren't stuck open, by just going to a junkyard or buying a good set)
-Check your Knock Sensor
-Check your Oil related things (Is it good oil? What about the filter? What about your pump?)
-Check your Fuel Lines
-Check the FPR
-Check the Fuel Pump
-Check what could be straining the alternator, check for bad grounds, weak battery, etc.
-Check out your A/C system.
-Clean out your EGR
-Replace your PCVs
-Check your EVAP system
-Check your cooling system (Radiator, Radiator Cap, Fans, lines)
-Replace the Front Heated O2 Sensor (I'm just quoting the FSM... shaddup)
-Check the Vehicle SPeed Sensor????? (FSM says so... Since it is the bible around here I guess you better check it!)
-Park Neutral Circuit (Well... Check it... Even though mine has been disconnected since I swapped transmissions)
-At this point in time the only things left to check are the actual mechanical parts of the motor, which at this point, you're better off replacing the motor.
That's it... That's a complete list of what the FSM says check (Engine wise), I may miss 1 or 2 things but really after doing all of that, and you still get 9-12 mpg.... It's not anything connected to the motor atleast!
That short ram is the least of your worries right now, FWIW I have a SRI.
Last edited by aackshun; 04-05-2011 at 09:24 AM.
04-05-2011, 10:37 AM
#32
04-05-2011, 11:32 AM
#33
Senior Member
Join Date: Jun 2003
Location: Ottawa
Posts: 375
You could do 1 of 2 types of SeaFoam cleaning applications. One involves inhaling a 1/2 tin or so thru the brake vacuum line right into the fuel intake up end. Then the other 1/2 in the oil and and another portion in gas tank. Change the oil right away after the upper end cleaning and do it somewhere you can account for white cloud the size of an aircraft carrier. You should get some improvement right away. Other than that, I do notice a significant relation to fuel and the front o2 sensors, the cat 4 wire doesn't affect mileage as it doesn't adjust air to fuel mixture. When did you last change your sparkplugs and are they the correct ones. coils? air filter? Do you burn 87 octane or 94.... many factors but seafoam will atleast have you clean and isn't expensive.
04-05-2011, 01:37 PM
#34
So...
In my personal expierience bad O2s have not affected performance or mpgs.
Last edited by aackshun; 04-05-2011 at 01:39 PM.
04-05-2011, 01:40 PM
#35
I consider them the same, since I've gotten a license I have been driving 300 + miles a week (really closer to 400, the 300 was just based on work and school only, that's not including me going out at night)
So...
In my personal expierience bad O2s have not affected performance or mpgs.
So...
In my personal expierience bad O2s have not affected performance or mpgs.
04-05-2011, 01:48 PM
#38
no the Diamante is near 4klbs, i'd say it's freakishly heavy, also in pretty rough shape, the o2s are the least of it's problems right now, it's chilling in the garage cause it's getting MPQs... Miles per quarts (of coolant)
04-05-2011, 01:50 PM
#39
Supporting Maxima.org Member
iTrader: (29)
Join Date: Oct 2005
Location: Middleboro/Carver, Ma
Posts: 4,572
If your car was actually getting 10mpg you would have serious driveability problems and a cel, or you would definitly be smelling gas, so since you didn't mention any of those it's one of the following-
You skipped 3rd grade
you DID complete the third grade, but failed to lay off the bong rips before computing your mpg
Your gas station has a metering problem (I once filled up 3 different cars at a local sunoco w/93 for like $2......... $2 to fill the tank! Computer glitch ftw)
You are idling for hours at a time
You have a remote start that is starting up your car for a few hours every night
Someone is borrowing your car without you knowing
Someone is stealing your gas, not easy to do on a maxima.
You skipped 3rd grade
you DID complete the third grade, but failed to lay off the bong rips before computing your mpg
Your gas station has a metering problem (I once filled up 3 different cars at a local sunoco w/93 for like $2......... $2 to fill the tank! Computer glitch ftw)
You are idling for hours at a time
You have a remote start that is starting up your car for a few hours every night
Someone is borrowing your car without you knowing
Someone is stealing your gas, not easy to do on a maxima.
04-05-2011, 01:54 PM
#40
Supporting Maxima.org Member
iTrader: (29)
Join Date: Oct 2005
Location: Middleboro/Carver, Ma
Posts: 4,572
-Check EVERYTHING that has to do with Air, from Air cleaner to Throttle Body, then make sure your Idle is correct (Make sure it's within spec 550-750)
-Make sure your TPS is working and Adjusted
-Check your MAF
-Check the Engine Coolant Temp Sensor
-Check the Injectors (Says check the wiring? I'd also make sure a few of them aren't stuck open, by just going to a junkyard or buying a good set)
-Check your Knock Sensor
-Check your Oil related things (Is it good oil? What about the filter? What about your pump?)
-Check your Fuel Lines
-Check the FPR
-Check the Fuel Pump
-Check what could be straining the alternator, check for bad grounds, weak battery, etc.
-Check out your A/C system.
-Clean out your EGR
-Replace your PCVs
-Check your EVAP system
-Check your cooling system (Radiator, Radiator Cap, Fans, lines)
-Replace the Front Heated O2 Sensor (I'm just quoting the FSM... shaddup)
-Check the Vehicle SPeed Sensor????? (FSM says so... Since it is the bible around here I guess you better check it!)
-Park Neutral Circuit (Well... Check it... Even though mine has been disconnected since I swapped transmissions)
-At this point in time the only things left to check are the actual mechanical parts of the motor, which at this point, you're better off replacing the motor.
Also, you're crazy if you think o2s don't effect performance or MPG. I've seen plenty of cars get p0300's during casual driving