Why is my MPG so poor?
11-27-2014, 10:35 AM
#42
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.
He definitely mentioned in his OP that he has kept maintenance up to date.. new plugs n coils, as well as clean "filters."
11-27-2014, 03:27 PM
#43
Senior Member
Join Date: Dec 2005
Posts: 1,215
Fill up when the light turns on it should be about 300 miles till it lights up again.
10mpg is like 190 miles a tank maybe.
If it is I would get your injectors cleaned. One or two are probably leaking bad.
It's cheap to do.
10mpg is like 190 miles a tank maybe.
If it is I would get your injectors cleaned. One or two are probably leaking bad.
It's cheap to do.
11-27-2014, 06:00 PM
#44
11-27-2014, 06:03 PM
#45
I use a gumout concentrated injector cleaner every 3,000 miles, but how am I able to clean the injectors?
11-27-2014, 06:40 PM
#48
Senior Member
Join Date: Dec 2005
Posts: 1,215
If it were me I'd go to the junkyard and buy a set of injectors and send
the ones you have to get flow matched. It is not expensive, cheap actually.
This guy is a bargain you'd be completely stupid not to do this you can't be THAT cheap.
http://www.r3vlimited.com/board/showthread.php?t=266477
Don't idle it for 15 min on a cold start that wastes allot gas too. It'll warm up faster
if you drive it right away then 15 min idling I think. :P
the ones you have to get flow matched. It is not expensive, cheap actually.
This guy is a bargain you'd be completely stupid not to do this you can't be THAT cheap.
http://www.r3vlimited.com/board/showthread.php?t=266477
Don't idle it for 15 min on a cold start that wastes allot gas too. It'll warm up faster
if you drive it right away then 15 min idling I think. :P
11-28-2014, 09:27 PM
#50
http://www.deatschwerks.com/services...ector-services
Or buy a used set that's already cleaned and refurbished from Ebay.
http://www.ebay.com/itm/5-YEAR-WARRA...item1c3f69effa
Or yank a set from the salvage yard and send them in for cleaning.
The last two options, you won't have any down time with your Max. Deatchwerks has two sets of injectors of mine for cleaning and refurbishing.
11-28-2014, 10:01 PM
#51
Saw some videos on YouTube for do it yourself injector cleaning.
Doesn't look too hard or expensive.
I'm giving it a go someday..I have a lot of injectors.
You seen any of those vids wizzy?
Any opinions of so?..
Doesn't look too hard or expensive.
I'm giving it a go someday..I have a lot of injectors.
You seen any of those vids wizzy?
Any opinions of so?..
11-29-2014, 06:47 AM
#52
11-29-2014, 06:52 AM
#53
You can't. You have to pull your injectors and send them in for cleaning to a company like Deatchwerks. Your car will be down for 2 weeks minimum as they're busy.
http://www.deatschwerks.com/services...ector-services
Or buy a used set that's already cleaned and refurbished from Ebay.
http://www.ebay.com/itm/5-YEAR-WARRA...item1c3f69effa
Or yank a set from the salvage yard and send them in for cleaning.
The last two options, you won't have any down time with your Max. Deatchwerks has two sets of injectors of mine for cleaning and refurbishing.
11-29-2014, 08:26 AM
#54
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
11-29-2014, 08:32 AM
#55
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
11-29-2014, 08:38 AM
#56
11-29-2014, 09:49 AM
#57
11-29-2014, 11:06 AM
#59
Here's all the info I got from the obd scanner, http://s1381.photobucket.com/user/ar...0Maxima%20Obd2
11-29-2014, 02:55 PM
#61
Yes download the fsm an look in the ec section for the way to troubleshoot your o2 sensors look for other probable causes like exhaust leaks,fuel pressure,fuel injectors or Intake leaks not to mention maf activity...
You got the fancy tool now the fsm will make all the info a bit more clear...
You got the fancy tool now the fsm will make all the info a bit more clear...
11-29-2014, 09:56 PM
#63
I made a trip to and from peoria,IL from joliet,IL last month mostly highway, but quite a bit of city driving too and got me 372 miles on 1 tank. would have been more if i had all highway. Also i refilled at just under 1/4 of a tank. Had i ran it until the light came on i could have easily gotten at least 50 more miles.
11-30-2014, 06:09 AM
#64
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
^^ Sorry for the delay in response bud, Saturday was quite hectic.
I looked at pics, HOLY $HITE something is seriously wrong with your car. Let me list off all the things I notice first:
- Short term fuel trims Bank 1/Bank 2 sensor 2 on both is retarded super high at +99.2. Which is the maximum within the specified range, that means the car is trying to pump as much fuel in as possible for some reason.
Then, looking at LTFT Bank 2 it's STILL trying to add more fuel.
Your ignition timing is off at 10*BTDC. It should be 15* at idle. But considering the amount of fuel in the engine, not surprising that timing is retarded too.
IAT of 136F is way too high this time of year, unless you sat in a hot *** room for a while. IAT should be about same as ambient temps when moving, and maybe like 10-20* hotter if idling for a while, but that still means like maybe 60F not 136F..
MAF looks fine, that's about 4.5 g/s which is within the normal range at idle.
ECT is at 192F which is fine, so that looks normal.
All in all, you likely have bad/leaky injectors and possibly a huge vacuum leak with the car trying to compensate for the extra air by adding more fuel.
In your case, I would get those injectors tested, then look for air leaks in your intake (before MAF). Also test your o2 sensors, I think you might need a pair of primaries.
And while you fix this, the WORST thing you can do is idle the car for 15 minutes while it's just dumping tons of fuel in there as soon as it goes to closed loop. Driving it will save as much fuel as you possibly can, until you fix this
I looked at pics, HOLY $HITE something is seriously wrong with your car. Let me list off all the things I notice first:
- Short term fuel trims Bank 1/Bank 2 sensor 2 on both is retarded super high at +99.2. Which is the maximum within the specified range, that means the car is trying to pump as much fuel in as possible for some reason.
Then, looking at LTFT Bank 2 it's STILL trying to add more fuel.
Your ignition timing is off at 10*BTDC. It should be 15* at idle. But considering the amount of fuel in the engine, not surprising that timing is retarded too.
IAT of 136F is way too high this time of year, unless you sat in a hot *** room for a while. IAT should be about same as ambient temps when moving, and maybe like 10-20* hotter if idling for a while, but that still means like maybe 60F not 136F..
MAF looks fine, that's about 4.5 g/s which is within the normal range at idle.
ECT is at 192F which is fine, so that looks normal.
All in all, you likely have bad/leaky injectors and possibly a huge vacuum leak with the car trying to compensate for the extra air by adding more fuel.
In your case, I would get those injectors tested, then look for air leaks in your intake (before MAF). Also test your o2 sensors, I think you might need a pair of primaries.
And while you fix this, the WORST thing you can do is idle the car for 15 minutes while it's just dumping tons of fuel in there as soon as it goes to closed loop. Driving it will save as much fuel as you possibly can, until you fix this
11-30-2014, 07:35 AM
#65
^^ Sorry for the delay in response bud, Saturday was quite hectic.
I looked at pics, HOLY $HITE something is seriously wrong with your car. Let me list off all the things I notice first:
- Short term fuel trims Bank 1/Bank 2 sensor 2 on both is retarded super high at +99.2. Which is the maximum within the specified range, that means the car is trying to pump as much fuel in as possible for some reason.
Then, looking at LTFT Bank 2 it's STILL trying to add more fuel.
Your ignition timing is off at 10*BTDC. It should be 15* at idle. But considering the amount of fuel in the engine, not surprising that timing is retarded too.
IAT of 136F is way too high this time of year, unless you sat in a hot *** room for a while. IAT should be about same as ambient temps when moving, and maybe like 10-20* hotter if idling for a while, but that still means like maybe 60F not 136F..
MAF looks fine, that's about 4.5 g/s which is within the normal range at idle.
ECT is at 192F which is fine, so that looks normal.
All in all, you likely have bad/leaky injectors and possibly a huge vacuum leak with the car trying to compensate for the extra air by adding more fuel.
In your case, I would get those injectors tested, then look for air leaks in your intake (before MAF). Also test your o2 sensors, I think you might need a pair of primaries.
And while you fix this, the WORST thing you can do is idle the car for 15 minutes while it's just dumping tons of fuel in there as soon as it goes to closed loop. Driving it will save as much fuel as you possibly can, until you fix this
I looked at pics, HOLY $HITE something is seriously wrong with your car. Let me list off all the things I notice first:
- Short term fuel trims Bank 1/Bank 2 sensor 2 on both is retarded super high at +99.2. Which is the maximum within the specified range, that means the car is trying to pump as much fuel in as possible for some reason.
Then, looking at LTFT Bank 2 it's STILL trying to add more fuel.
Your ignition timing is off at 10*BTDC. It should be 15* at idle. But considering the amount of fuel in the engine, not surprising that timing is retarded too.
IAT of 136F is way too high this time of year, unless you sat in a hot *** room for a while. IAT should be about same as ambient temps when moving, and maybe like 10-20* hotter if idling for a while, but that still means like maybe 60F not 136F..
MAF looks fine, that's about 4.5 g/s which is within the normal range at idle.
ECT is at 192F which is fine, so that looks normal.
All in all, you likely have bad/leaky injectors and possibly a huge vacuum leak with the car trying to compensate for the extra air by adding more fuel.
In your case, I would get those injectors tested, then look for air leaks in your intake (before MAF). Also test your o2 sensors, I think you might need a pair of primaries.
And while you fix this, the WORST thing you can do is idle the car for 15 minutes while it's just dumping tons of fuel in there as soon as it goes to closed loop. Driving it will save as much fuel as you possibly can, until you fix this
2-Is there any way that I can test the injectors myself? Or I'm better off just buying the refurbished ones?
Thanks very much for all your help.
11-30-2014, 08:00 AM
#66
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
1-Does the tension of the timing chain can cause all these problems? Because I stated that in one of my posts that the timing chain makes a rattling sound.
2-Is there any way that I can test the injectors myself? Or I'm better off just buying the refurbished ones?
Thanks very much for all your help.
1. No
2. Yes, there is resistance test which isnt really helpful to see if an injector is sticking...youd need to pull em off and test em for pressure and spray pattern, not easy to do unless you have a shop so I would probably have a trusted mechanic do this for you.
It would also be helpful if you could monitor data to see what happens at open loop (thats right when engine is started cold, before it reaches operating temp). Your pics were all from closed loop operation...If the car is also running rich in open loop that would point me more towards a possible air leak (exhaust leak possibly) because the extra air in exhaust stream would be causing the o2's to go wild and add bunch of fuel.
11-30-2014, 08:28 AM
#67
No problem, hope you find and fix the issue.
1. No
2. Yes, there is resistance test which isnt really helpful to see if an injector is sticking...youd need to pull em off and test em for pressure and spray pattern, not easy to do unless you have a shop so I would probably have a trusted mechanic do this for you.
It would also be helpful if you could monitor data to see what happens at open loop (thats right when engine is started cold, before it reaches operating temp). Your pics were all from closed loop operation...If the car is also running rich in open loop that would point me more towards a possible air leak (exhaust leak possibly) because the extra air in exhaust stream would be causing the o2's to go wild and add bunch of fuel.
11-30-2014, 11:23 AM
#68
New pictures added as you asked, Live Data is right after starting the car when cold, and also added different data that I found.
http://s1381.photobucket.com/user/ar...OBD2%20Scanner
http://s1381.photobucket.com/user/ar...OBD2%20Scanner
Last edited by argenis69; 11-30-2014 at 11:27 AM.
11-30-2014, 12:45 PM
#69
Junior Member
Join Date: Aug 2013
Location: Germany
Posts: 42
Feel your rims after you drive it a while. If they are screaming hot, you're brakes are dragging like others have suggested. Though I also had this symptom with a bad bearing condition too.
My car rarely warms up with my 2 mile commute to work 4 times a day (I often go home for lunch and it's illegal to idle in Germany) and am getting about 20 mpg in thoe conditions. 22-26 mpg when I do take a road trip (100mph on the autobahn sustained eats the fuel too!)...
So, it might also be worth taking it on a highway run for a few hours if you haven't lately. I had a Dodge Neon in Alaska that was getting <15mpg since I only drove it 1-2 miles to work and never left town in the sub freezing temps for months -albeit extreme conditions- the mileage sucked for an economy car. I drove it 6 hours sustained HWY to Anchorage one day and started getting 40 mpg on the return trip after blowing out all the crap in my engine. Might be time to take a drive -and measure your HWY mpgs to compare/contrast.
Just some ideas.
Regarding the images, The Cylinder one timing advance value of 10 concerns me. I don't know for certain, but I would have guessed that would be 0-2 if the value is in degrees. But it could be spot on.
Also, any chance your odometer is not working properly, are you refueling as frequently as 157 miles would dictate? Maybe it's loose in some manner and not spinning 1:1 with the wheels?
My car rarely warms up with my 2 mile commute to work 4 times a day (I often go home for lunch and it's illegal to idle in Germany) and am getting about 20 mpg in thoe conditions. 22-26 mpg when I do take a road trip (100mph on the autobahn sustained eats the fuel too!)...
So, it might also be worth taking it on a highway run for a few hours if you haven't lately. I had a Dodge Neon in Alaska that was getting <15mpg since I only drove it 1-2 miles to work and never left town in the sub freezing temps for months -albeit extreme conditions- the mileage sucked for an economy car. I drove it 6 hours sustained HWY to Anchorage one day and started getting 40 mpg on the return trip after blowing out all the crap in my engine. Might be time to take a drive -and measure your HWY mpgs to compare/contrast.
Just some ideas.
Regarding the images, The Cylinder one timing advance value of 10 concerns me. I don't know for certain, but I would have guessed that would be 0-2 if the value is in degrees. But it could be spot on.
Also, any chance your odometer is not working properly, are you refueling as frequently as 157 miles would dictate? Maybe it's loose in some manner and not spinning 1:1 with the wheels?
Last edited by Phantasm; 11-30-2014 at 12:57 PM.
11-30-2014, 12:59 PM
#70
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
Alright bro. I looked thru many of em, will look more later.
From what I see its exactly what I thought. If you notice this time your fuel trims are completely different but your o2's (all of them) are reading lean. Injector pulse at 3 confirms that, should be closer to 2 at idle not 3.
Hows your exhaust looking? I would seriously suspect an air leak. Exhaust or maybe intake.
I'll chime in some more in a bit.
From what I see its exactly what I thought. If you notice this time your fuel trims are completely different but your o2's (all of them) are reading lean. Injector pulse at 3 confirms that, should be closer to 2 at idle not 3.
Hows your exhaust looking? I would seriously suspect an air leak. Exhaust or maybe intake.
I'll chime in some more in a bit.
11-30-2014, 07:01 PM
#71
Alright bro. I looked thru many of em, will look more later.
From what I see its exactly what I thought. If you notice this time your fuel trims are completely different but your o2's (all of them) are reading lean. Injector pulse at 3 confirms that, should be closer to 2 at idle not 3.
Hows your exhaust looking? I would seriously suspect an air leak. Exhaust or maybe intake.
I'll chime in some more in a bit.
From what I see its exactly what I thought. If you notice this time your fuel trims are completely different but your o2's (all of them) are reading lean. Injector pulse at 3 confirms that, should be closer to 2 at idle not 3.
Hows your exhaust looking? I would seriously suspect an air leak. Exhaust or maybe intake.
I'll chime in some more in a bit.
12-02-2014, 05:12 AM
#72
Alright bro. I looked thru many of em, will look more later.
From what I see its exactly what I thought. If you notice this time your fuel trims are completely different but your o2's (all of them) are reading lean. Injector pulse at 3 confirms that, should be closer to 2 at idle not 3.
Hows your exhaust looking? I would seriously suspect an air leak. Exhaust or maybe intake.
I'll chime in some more in a bit.
From what I see its exactly what I thought. If you notice this time your fuel trims are completely different but your o2's (all of them) are reading lean. Injector pulse at 3 confirms that, should be closer to 2 at idle not 3.
Hows your exhaust looking? I would seriously suspect an air leak. Exhaust or maybe intake.
I'll chime in some more in a bit.
I'll be filling up again on Friday to have another mpg calculation.
12-04-2014, 04:08 AM
#73
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
Hey sorry forgot to chime in again...
Out of all Ive seen I would start looking for an air leak if I was you. Look over the entire exhaust (especially around engine firewall area/rear pre cat where the flex section is) and look for leaks.
Then if you dont find any issues there, look for intake leaks past the MAF.
Those things Id focus on, in that order. And if you somehow dont have any leaks then I would probably look into your o2 sensors.
This really doesnt seem like a fuel injector issue to me. Looks like an unmetered air leak.
Out of all Ive seen I would start looking for an air leak if I was you. Look over the entire exhaust (especially around engine firewall area/rear pre cat where the flex section is) and look for leaks.
Then if you dont find any issues there, look for intake leaks past the MAF.
Those things Id focus on, in that order. And if you somehow dont have any leaks then I would probably look into your o2 sensors.
This really doesnt seem like a fuel injector issue to me. Looks like an unmetered air leak.
12-04-2014, 05:11 AM
#74
Hey sorry forgot to chime in again...
Out of all Ive seen I would start looking for an air leak if I was you. Look over the entire exhaust (especially around engine firewall area/rear pre cat where the flex section is) and look for leaks.
Then if you dont find any issues there, look for intake leaks past the MAF.
Those things Id focus on, in that order. And if you somehow dont have any leaks then I would probably look into your o2 sensors.
This really doesnt seem like a fuel injector issue to me. Looks like an unmetered air leak.
Out of all Ive seen I would start looking for an air leak if I was you. Look over the entire exhaust (especially around engine firewall area/rear pre cat where the flex section is) and look for leaks.
Then if you dont find any issues there, look for intake leaks past the MAF.
Those things Id focus on, in that order. And if you somehow dont have any leaks then I would probably look into your o2 sensors.
This really doesnt seem like a fuel injector issue to me. Looks like an unmetered air leak.
That's interesting, I'll try to check all that this weekend.
Is there any specific method to help check for those leaks?
12-18-2014, 08:52 AM
#75
So, I filled up again 2 days ago and I only got 161 miles per tank with 16.69 gal. http://i1381.photobucket.com/albums/...psbkrk99a3.jpg
12-19-2014, 08:22 PM
#76
Supporting Maxima.org Member
iTrader: (15)
Join Date: Oct 2003
Location: Indianapolis, IN
Posts: 744
wow, still going, not good.
what about a fuel leak? if you park in a garage, the smell would be obvious. i had to replace my o-ring when accessing the fuel pump b/c mine was leaking once.
can you list out what you have checked in one post? many suggestions on what to check, we can start to pinpoint this.
what about a fuel leak? if you park in a garage, the smell would be obvious. i had to replace my o-ring when accessing the fuel pump b/c mine was leaking once.
can you list out what you have checked in one post? many suggestions on what to check, we can start to pinpoint this.
12-19-2014, 09:23 PM
#77
wow, still going, not good.
what about a fuel leak? if you park in a garage, the smell would be obvious. i had to replace my o-ring when accessing the fuel pump b/c mine was leaking once.
can you list out what you have checked in one post? many suggestions on what to check, we can start to pinpoint this.
what about a fuel leak? if you park in a garage, the smell would be obvious. i had to replace my o-ring when accessing the fuel pump b/c mine was leaking once.
can you list out what you have checked in one post? many suggestions on what to check, we can start to pinpoint this.
Problem is, I haven't had the time and/or convenient weather to be able to troubleshoot, but I'll be back home by next month and there I'll start doing all the test you guys have suggested me.
12-20-2014, 04:54 AM
#78
Senior Member
Join Date: May 2013
Location: Snakeden Branch, VA
Posts: 1,441
^^ I figured you haven't checked anything yet. You're not gonna find your problem by just filling up only to find your mpg still sucks every time.
Dude, just turn the car on when its dark and use a flashlight or better yet a black light to look under car for smoke leaks. Thats the first, and easiest thing you can do. If you have a leak, it should present itself clearly. Humid weather helps cuz more smoke is seen that way.
Otherwise you're just doing guesswork and never gonna get anywhere.
Dude, just turn the car on when its dark and use a flashlight or better yet a black light to look under car for smoke leaks. Thats the first, and easiest thing you can do. If you have a leak, it should present itself clearly. Humid weather helps cuz more smoke is seen that way.
Otherwise you're just doing guesswork and never gonna get anywhere.
01-17-2015, 12:31 PM
#79
wow, still going, not good.
what about a fuel leak? if you park in a garage, the smell would be obvious. i had to replace my o-ring when accessing the fuel pump b/c mine was leaking once.
can you list out what you have checked in one post? many suggestions on what to check, we can start to pinpoint this.
what about a fuel leak? if you park in a garage, the smell would be obvious. i had to replace my o-ring when accessing the fuel pump b/c mine was leaking once.
can you list out what you have checked in one post? many suggestions on what to check, we can start to pinpoint this.
01-17-2015, 01:25 PM
#80
^^ I figured you haven't checked anything yet. You're not gonna find your problem by just filling up only to find your mpg still sucks every time.
Dude, just turn the car on when its dark and use a flashlight or better yet a black light to look under car for smoke leaks. Thats the first, and easiest thing you can do. If you have a leak, it should present itself clearly. Humid weather helps cuz more smoke is seen that way.
Otherwise you're just doing guesswork and never gonna get anywhere.
Dude, just turn the car on when its dark and use a flashlight or better yet a black light to look under car for smoke leaks. Thats the first, and easiest thing you can do. If you have a leak, it should present itself clearly. Humid weather helps cuz more smoke is seen that way.
Otherwise you're just doing guesswork and never gonna get anywhere.
So, I went and bought carb cleaner, started the engine, and started spraying carb cleaner on each of the vacuum lines, the evap lines and sensors, also all around the injen intake tubes and couplers, the maf, etc.
A mechanic told me to do this and if there's a leak or anything broken, the car's idle will go up or down when I spray on the leak. And after I did all that spraying and repeated the process, I found no leaks(the idle and/or the engine sound never changed).
After that I got under the car, and looked slowly twice for exhaust leaks and did not find any smoke leaks.(Outside Temperature was @ 20°F at that moment was 2:00pm).
What else can I do to finally figure out what's causing this?
Last edited by argenis69; 01-17-2015 at 01:35 PM.