Car mpg is terrible...cant fix
03-19-2012, 10:29 AM
#1
Burning Brakes
Thread Starter
Car mpg is terrible...cant fix
Posted in wrong section before:
I had reported some issues with having low gas mileage after my O2 crapped out and threw a code. During that time the car averaged 15-16 mpg.
After replacing the O2 sensor, the car mpg improved to 19-20 mpg but that was still considerably low to what it used to run. I'm getting 200-250 miles to the tank when I used to get at least 350.
Replaced the spark plugs and then when to do some mpg tests (highway cruise, light on gas pedal runs). The mpg averaged back up to 24-25; but then over time started to dip again with each tank.
The car again averages 19-20 mpg. I've noticed that the car uses considerable fuel now, especially when stopped at an idle. This is based purely on the car's trip computer readings (I have an 06).
Before: Idle at light, (reset trip computer), accelerate within city limits - car averages 0.0 mpg to 16.0 mpg to 20 mpg and then increases gradually to 25+ mpg after getting on highway.
Now: Idle at light, (reset trip computer), accelerate within city limits - car averages 0.0 mpg to 8.0 mpg to 10 mpg then i need to really carefully coast to get it to jump and ceiling at 20 mpg even after driving on highway.
It just seems like the car is using just an excessive amount of fuel idling and accelerating...Anybody know what might be the issue. I've already ran a few tanks of techron concentrate every other tank three times already.
Air filters are clean too. I do have a yakima roof rack with fairing on top, but its never killed my mileage this poorly.
I had reported some issues with having low gas mileage after my O2 crapped out and threw a code. During that time the car averaged 15-16 mpg.
After replacing the O2 sensor, the car mpg improved to 19-20 mpg but that was still considerably low to what it used to run. I'm getting 200-250 miles to the tank when I used to get at least 350.
Replaced the spark plugs and then when to do some mpg tests (highway cruise, light on gas pedal runs). The mpg averaged back up to 24-25; but then over time started to dip again with each tank.
The car again averages 19-20 mpg. I've noticed that the car uses considerable fuel now, especially when stopped at an idle. This is based purely on the car's trip computer readings (I have an 06).
Before: Idle at light, (reset trip computer), accelerate within city limits - car averages 0.0 mpg to 16.0 mpg to 20 mpg and then increases gradually to 25+ mpg after getting on highway.
Now: Idle at light, (reset trip computer), accelerate within city limits - car averages 0.0 mpg to 8.0 mpg to 10 mpg then i need to really carefully coast to get it to jump and ceiling at 20 mpg even after driving on highway.
It just seems like the car is using just an excessive amount of fuel idling and accelerating...Anybody know what might be the issue. I've already ran a few tanks of techron concentrate every other tank three times already.
Air filters are clean too. I do have a yakima roof rack with fairing on top, but its never killed my mileage this poorly.
03-19-2012, 10:34 AM
#3
Burning Brakes
Thread Starter
I know its winter blended fuel, but its never been this low in past winters. I can't even get it to average above 26 consistently highway with cruise control under 60.
I used to be able to average 34+ on the highway with cruise control if not 30+ on slightly graded highways. It feels like its just bleeding fuel.
I used to be able to average 34+ on the highway with cruise control if not 30+ on slightly graded highways. It feels like its just bleeding fuel.
03-19-2012, 07:47 PM
#5
Check brakes for a binding caliper pin or caliper piston. Turn wheel. It should turn easily w/ slight drag of pad. If very difficult to turn, something is wrong.
Have car scanned to look for something off but not enough to set code, perhaps Long Term Fuel Trim (LTFT) running rich. Negative LTFT indicates a rich condition and ECU is reducing fuel to try and maintain correct fuel/air mix.
good luck
Have car scanned to look for something off but not enough to set code, perhaps Long Term Fuel Trim (LTFT) running rich. Negative LTFT indicates a rich condition and ECU is reducing fuel to try and maintain correct fuel/air mix.
good luck
03-20-2012, 11:07 AM
#6
Burning Brakes
Thread Starter
That is some new advice I haven't thought about yet. Thank you! I will definitely give this a try. Any other thoughts what it might be?
When the first O2 sensor went to crap, it just never went back in terms of fuel mileage. Could there be any build up from running rich on a crap O2 for a few tanks before replacing?
When the first O2 sensor went to crap, it just never went back in terms of fuel mileage. Could there be any build up from running rich on a crap O2 for a few tanks before replacing?
Check brakes for a binding caliper pin or caliper piston. Turn wheel. It should turn easily w/ slight drag of pad. If very difficult to turn, something is wrong.
Have car scanned to look for something off but not enough to set code, perhaps Long Term Fuel Trim (LTFT) running rich. Negative LTFT indicates a rich condition and ECU is reducing fuel to try and maintain correct fuel/air mix.
good luck
Have car scanned to look for something off but not enough to set code, perhaps Long Term Fuel Trim (LTFT) running rich. Negative LTFT indicates a rich condition and ECU is reducing fuel to try and maintain correct fuel/air mix.
good luck
03-20-2012, 11:10 AM
#7
Burning Brakes
Thread Starter
Can I use any OBDII scanner to read the codes for LTFT and other such items? Getting to a mechanic is hard since they usually aren't open weekends around here and I work 7-7 every day.
Check brakes for a binding caliper pin or caliper piston. Turn wheel. It should turn easily w/ slight drag of pad. If very difficult to turn, something is wrong.
Have car scanned to look for something off but not enough to set code, perhaps Long Term Fuel Trim (LTFT) running rich. Negative LTFT indicates a rich condition and ECU is reducing fuel to try and maintain correct fuel/air mix.
good luck
Have car scanned to look for something off but not enough to set code, perhaps Long Term Fuel Trim (LTFT) running rich. Negative LTFT indicates a rich condition and ECU is reducing fuel to try and maintain correct fuel/air mix.
good luck
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03-20-2012, 11:11 AM
#8
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Heavy aftermarket wheels? Sticky sport tires?
That would certainly affect it.
That would certainly affect it.
03-20-2012, 11:38 AM
#9
Burning Brakes
Thread Starter
Stock Rims, Wheels are Pole Potenzas which are heavier but I put them on nearly 3 years ago. Even with those wheels on i went from a 26.5 avg (mixed) to a 25.0 avg (mixed). Driving mostly highway these days, i'm lucky to get above 19.
03-20-2012, 12:56 PM
#10
when i had snow tires on my TL i'd average around 15 mpg city. Now with my summer tires on I average 19-20 mpg city. I see 29-30 mpg highway with summer tires and was getting 25 with snow tires. Our cars are sensitive to the wheels we put on it seems
03-20-2012, 04:24 PM
#11
Burning Brakes
Thread Starter
yeah, my tires affected my MPG. But that was years ago. When i first put on these tires in 2007/2008 they dropped my MPG from 26 average to 25 average in the winter.
Before my O2 sensor crapped out, i still averaged 24.5 mixed driving. The only things I changed was replacing O2 and spark plugs. The car MPG has never been the same before the O2 sensor crapped out.
Before my O2 sensor crapped out, i still averaged 24.5 mixed driving. The only things I changed was replacing O2 and spark plugs. The car MPG has never been the same before the O2 sensor crapped out.
03-21-2012, 08:12 AM
#13
Burning Brakes
Thread Starter
03-21-2012, 12:27 PM
#14
El Cunado
I posted this in your original thread, not knowing there was another:
Some thoughts:
How many miles on the car?
Normal servicing/maintenance record?
How much added weight in the car (cabin/trunk)?
Maybe clogged/dirty fuel filter?
Some thoughts:
How many miles on the car?
Normal servicing/maintenance record?
How much added weight in the car (cabin/trunk)?
Maybe clogged/dirty fuel filter?
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justnspace (03-21-2012)
03-21-2012, 02:35 PM
#15
Burning Brakes
Thread Starter
63,000 miles on the car.
Original owner - oil every 5-6k miles or twice a year (whichever came first), royal purple oil every time, no incidents, even did the unnecessary acura 20K maintenance intervals. Very strict about what goes into the car (gas has only been exxonmobil/shell for its entire life).
Nothing in trunk other than a sleeping bag. I have a roof rack with a air diffuser. However, I've already mentioned that the
I wouldn't know how to change a dirty fuel filter...but i'm under the impression those don't normally fail.
To be clear, the MPG didn't slowly drop to its current level. At 62,000 miles i was still averaging 24+ mpg mixed with the roof rack on top and with the heavier potenza tires. My O2 sensor died out of the blue and during that time I drove about 5 tanks worth of gas before I had a chance to replace the O2 sensor. During the failed O2 sensor, I averaged 15.0 MPG. Replaced the O2 sensor and noticed MPG only averaged at most 19 MPG. Changed the spark plugs, no difference.
Original owner - oil every 5-6k miles or twice a year (whichever came first), royal purple oil every time, no incidents, even did the unnecessary acura 20K maintenance intervals. Very strict about what goes into the car (gas has only been exxonmobil/shell for its entire life).
Nothing in trunk other than a sleeping bag. I have a roof rack with a air diffuser. However, I've already mentioned that the
I wouldn't know how to change a dirty fuel filter...but i'm under the impression those don't normally fail.
To be clear, the MPG didn't slowly drop to its current level. At 62,000 miles i was still averaging 24+ mpg mixed with the roof rack on top and with the heavier potenza tires. My O2 sensor died out of the blue and during that time I drove about 5 tanks worth of gas before I had a chance to replace the O2 sensor. During the failed O2 sensor, I averaged 15.0 MPG. Replaced the O2 sensor and noticed MPG only averaged at most 19 MPG. Changed the spark plugs, no difference.
03-21-2012, 02:37 PM
#16
Burning Brakes
Thread Starter
Some new things I noticed. On start up, my car idle jumps to about 2,100-2,200 RPM; when its warm it drops to 700 rpm. Warm idle seems fine, is my cold (or cool in this warm weather) idle too high?
03-21-2012, 09:37 PM
#17
in the 24th and a half...
That idle is WAY too high.
On the cat issues, here's a cut and paste on the potential issue:
"Catalytic converter failures typically fall into one of four categories:
1. Thermal failure (overheating)
2. Plugged substrate
3. Thermal shock
4. Physical damage
Thermal failure is most often caused when excessive raw fuel comes into contact with the catalyst, and "burns" in the converter instead of in the engine. The high quantity of fuel generates temperatures well in excess of the capacity of the converter, causing meltdown of the ceramic monolith. The melted ceramic could block the exhaust path, leading to a significant loss of engine power. Visible symptoms include heat-related discoloration of the converter shell.
Potential causes of thermal failure include: misfire, malfunctioning oxygen sensor, fuel delivery issue, improper choke setting/operation, and ECU malfunction.
A plugged or contaminated substrate can be the result of an overly rich air/fuel mixture, radiator sealant, and oil or antifreeze entering the exhaust flow. The resultant carbon deposits restrict the operation - and ultimately the flow characteristics - of the converter by coating the unit's reactive surface. This degrades the converter's ability to perform its chemical conversion process, leading to potentially illegal levels of HC, CO, and NOx.
Root causes of this problem are a malfunctioning O2 sensor, plugged or inoperable fuel injectors, piston blow-by, leaking head gasket, broken or frozen choke or carburetor float, excessive cranking time, and repeated incidences of running out of gas.
Thermal shock occurs when a fully heated converter suddenly is "cold-quenched," such as coming into contact with snqw or ice. This leads to sudden contraction of the converter housing, which can cause cracks and disintegration of the ceramic substrate. Symptoms include a "rattling'' sound when the converter is tapped with a fist or mallet (monolith-type converters only).
Physical damage, caused by running over road debris, collisions and other impacts, is usually easy to diagnose. This type of damage can break up the ceramic substrate or cause restriction that changes the flow characteristics of the converter or impacts the efficiency of the catalyst."
OK, does your car still rev freely? (Note that neutral revs are limited by the ECU) Is performance down noticably? The easiest check would be to compare exhaust output between your car and another TSX...a simple feel test might show less "pressure" from your exhaust. Otherwise, an emissions test might show a problem...but I'd expect a code from this.
On the cat issues, here's a cut and paste on the potential issue:
"Catalytic converter failures typically fall into one of four categories:
1. Thermal failure (overheating)
2. Plugged substrate
3. Thermal shock
4. Physical damage
Thermal failure is most often caused when excessive raw fuel comes into contact with the catalyst, and "burns" in the converter instead of in the engine. The high quantity of fuel generates temperatures well in excess of the capacity of the converter, causing meltdown of the ceramic monolith. The melted ceramic could block the exhaust path, leading to a significant loss of engine power. Visible symptoms include heat-related discoloration of the converter shell.
Potential causes of thermal failure include: misfire, malfunctioning oxygen sensor, fuel delivery issue, improper choke setting/operation, and ECU malfunction.
A plugged or contaminated substrate can be the result of an overly rich air/fuel mixture, radiator sealant, and oil or antifreeze entering the exhaust flow. The resultant carbon deposits restrict the operation - and ultimately the flow characteristics - of the converter by coating the unit's reactive surface. This degrades the converter's ability to perform its chemical conversion process, leading to potentially illegal levels of HC, CO, and NOx.
Root causes of this problem are a malfunctioning O2 sensor, plugged or inoperable fuel injectors, piston blow-by, leaking head gasket, broken or frozen choke or carburetor float, excessive cranking time, and repeated incidences of running out of gas.
Thermal shock occurs when a fully heated converter suddenly is "cold-quenched," such as coming into contact with snqw or ice. This leads to sudden contraction of the converter housing, which can cause cracks and disintegration of the ceramic substrate. Symptoms include a "rattling'' sound when the converter is tapped with a fist or mallet (monolith-type converters only).
Physical damage, caused by running over road debris, collisions and other impacts, is usually easy to diagnose. This type of damage can break up the ceramic substrate or cause restriction that changes the flow characteristics of the converter or impacts the efficiency of the catalyst."
OK, does your car still rev freely? (Note that neutral revs are limited by the ECU) Is performance down noticably? The easiest check would be to compare exhaust output between your car and another TSX...a simple feel test might show less "pressure" from your exhaust. Otherwise, an emissions test might show a problem...but I'd expect a code from this.
03-22-2012, 08:45 AM
#18
Burning Brakes
Thread Starter
Checked my start-up idle today, it went back down to 1,500. Perhaps that high idle was due to it being freezing cold and I haven't used the car lately.
There doesn't seem to be any issues with the revs being hesitant, but then again I can't seem to remember how it first drove. I wish i had a stock tsx to compare it to, but i don't have access to one. My immediate thoughts are to get a OBD ii Scanner so that i can check the ST and the LT Trim to see if theres any issues with the fuel injectors.
After you/someone mentioned the cat being dead, I have a heavy suspicion this might be it. The car did go through 5 or so tanks of gas with a shotty O2 before being replaced. It was running super rich at that time. I wouldn't be surprised if it was just running at the brink of the O2 tolerance zones.
There doesn't seem to be any issues with the revs being hesitant, but then again I can't seem to remember how it first drove. I wish i had a stock tsx to compare it to, but i don't have access to one. My immediate thoughts are to get a OBD ii Scanner so that i can check the ST and the LT Trim to see if theres any issues with the fuel injectors.
After you/someone mentioned the cat being dead, I have a heavy suspicion this might be it. The car did go through 5 or so tanks of gas with a shotty O2 before being replaced. It was running super rich at that time. I wouldn't be surprised if it was just running at the brink of the O2 tolerance zones.
That idle is WAY too high.
On the cat issues, here's a cut and paste on the potential issue:
"Catalytic converter failures typically fall into one of four categories:
1. Thermal failure (overheating)
2. Plugged substrate
3. Thermal shock
4. Physical damage
Thermal failure is most often caused when excessive raw fuel comes into contact with the catalyst, and "burns" in the converter instead of in the engine. The high quantity of fuel generates temperatures well in excess of the capacity of the converter, causing meltdown of the ceramic monolith. The melted ceramic could block the exhaust path, leading to a significant loss of engine power. Visible symptoms include heat-related discoloration of the converter shell.
Potential causes of thermal failure include: misfire, malfunctioning oxygen sensor, fuel delivery issue, improper choke setting/operation, and ECU malfunction.
A plugged or contaminated substrate can be the result of an overly rich air/fuel mixture, radiator sealant, and oil or antifreeze entering the exhaust flow. The resultant carbon deposits restrict the operation - and ultimately the flow characteristics - of the converter by coating the unit's reactive surface. This degrades the converter's ability to perform its chemical conversion process, leading to potentially illegal levels of HC, CO, and NOx.
Root causes of this problem are a malfunctioning O2 sensor, plugged or inoperable fuel injectors, piston blow-by, leaking head gasket, broken or frozen choke or carburetor float, excessive cranking time, and repeated incidences of running out of gas.
Thermal shock occurs when a fully heated converter suddenly is "cold-quenched," such as coming into contact with snqw or ice. This leads to sudden contraction of the converter housing, which can cause cracks and disintegration of the ceramic substrate. Symptoms include a "rattling'' sound when the converter is tapped with a fist or mallet (monolith-type converters only).
Physical damage, caused by running over road debris, collisions and other impacts, is usually easy to diagnose. This type of damage can break up the ceramic substrate or cause restriction that changes the flow characteristics of the converter or impacts the efficiency of the catalyst."
OK, does your car still rev freely? (Note that neutral revs are limited by the ECU) Is performance down noticably? The easiest check would be to compare exhaust output between your car and another TSX...a simple feel test might show less "pressure" from your exhaust. Otherwise, an emissions test might show a problem...but I'd expect a code from this.
On the cat issues, here's a cut and paste on the potential issue:
"Catalytic converter failures typically fall into one of four categories:
1. Thermal failure (overheating)
2. Plugged substrate
3. Thermal shock
4. Physical damage
Thermal failure is most often caused when excessive raw fuel comes into contact with the catalyst, and "burns" in the converter instead of in the engine. The high quantity of fuel generates temperatures well in excess of the capacity of the converter, causing meltdown of the ceramic monolith. The melted ceramic could block the exhaust path, leading to a significant loss of engine power. Visible symptoms include heat-related discoloration of the converter shell.
Potential causes of thermal failure include: misfire, malfunctioning oxygen sensor, fuel delivery issue, improper choke setting/operation, and ECU malfunction.
A plugged or contaminated substrate can be the result of an overly rich air/fuel mixture, radiator sealant, and oil or antifreeze entering the exhaust flow. The resultant carbon deposits restrict the operation - and ultimately the flow characteristics - of the converter by coating the unit's reactive surface. This degrades the converter's ability to perform its chemical conversion process, leading to potentially illegal levels of HC, CO, and NOx.
Root causes of this problem are a malfunctioning O2 sensor, plugged or inoperable fuel injectors, piston blow-by, leaking head gasket, broken or frozen choke or carburetor float, excessive cranking time, and repeated incidences of running out of gas.
Thermal shock occurs when a fully heated converter suddenly is "cold-quenched," such as coming into contact with snqw or ice. This leads to sudden contraction of the converter housing, which can cause cracks and disintegration of the ceramic substrate. Symptoms include a "rattling'' sound when the converter is tapped with a fist or mallet (monolith-type converters only).
Physical damage, caused by running over road debris, collisions and other impacts, is usually easy to diagnose. This type of damage can break up the ceramic substrate or cause restriction that changes the flow characteristics of the converter or impacts the efficiency of the catalyst."
OK, does your car still rev freely? (Note that neutral revs are limited by the ECU) Is performance down noticably? The easiest check would be to compare exhaust output between your car and another TSX...a simple feel test might show less "pressure" from your exhaust. Otherwise, an emissions test might show a problem...but I'd expect a code from this.
03-22-2012, 08:52 AM
#20
Checked my start-up idle today, it went back down to 1,500. Perhaps that high idle was due to it being freezing cold and I haven't used the car lately.
There doesn't seem to be any issues with the revs being hesitant, but then again I can't seem to remember how it first drove. I wish i had a stock tsx to compare it to, but i don't have access to one. My immediate thoughts are to get a OBD ii Scanner so that i can check the ST and the LT Trim to see if theres any issues with the fuel injectors.
After you/someone mentioned the cat being dead, I have a heavy suspicion this might be it. The car did go through 5 or so tanks of gas with a shotty O2 before being replaced. It was running super rich at that time. I wouldn't be surprised if it was just running at the brink of the O2 tolerance zones.
There doesn't seem to be any issues with the revs being hesitant, but then again I can't seem to remember how it first drove. I wish i had a stock tsx to compare it to, but i don't have access to one. My immediate thoughts are to get a OBD ii Scanner so that i can check the ST and the LT Trim to see if theres any issues with the fuel injectors.
After you/someone mentioned the cat being dead, I have a heavy suspicion this might be it. The car did go through 5 or so tanks of gas with a shotty O2 before being replaced. It was running super rich at that time. I wouldn't be surprised if it was just running at the brink of the O2 tolerance zones.
If you haven't already done this. Run Seafoam with half tank of gas. I had an FX35 and ran it twice through my system... my highway mpg went up 4 miles almost instantly. FI were dirty
03-22-2012, 09:01 PM
#21
in the 24th and a half...
I would NOT seafoam if you suspect a damaged cat. I would look into a way to check the cat performance first...then, if it's OK, try injector cleaning.
03-23-2012, 07:11 PM
#22
I'm having a similar problem as the OP. Is there any other way to check for damage to the cat besides just a visual inspection?
03-23-2012, 10:28 PM
#23
in the 24th and a half...
No easy checks exist...removal and visual inspection is possible but difficult...back-pressure testing is complicated...running without the upstream O2 sensor can help if it is really clogged, but is very dangerous to do.
The simply fact is that running very rich for several days likely at least coated the catalyic converter honeycomb and ruined it's action, at worst it overheated it and melted it.
Badly clogged injectors would likely not cause poor fuel economy to the extent noted without severe misfires. The terrible fuel economy points to a bad converter...I would say the best option is an experienced shop with emission check equipment. Sorry, but that's the reality.
The simply fact is that running very rich for several days likely at least coated the catalyic converter honeycomb and ruined it's action, at worst it overheated it and melted it.
Badly clogged injectors would likely not cause poor fuel economy to the extent noted without severe misfires. The terrible fuel economy points to a bad converter...I would say the best option is an experienced shop with emission check equipment. Sorry, but that's the reality.
The following users liked this post:
DELIRIOUS_09 (03-24-2012)
03-24-2012, 03:45 AM
#24
No easy checks exist...removal and visual inspection is possible but difficult...back-pressure testing is complicated...running without the upstream O2 sensor can help if it is really clogged, but is very dangerous to do.
The simply fact is that running very rich for several days likely at least coated the catalyic converter honeycomb and ruined it's action, at worst it overheated it and melted it.
Badly clogged injectors would likely not cause poor fuel economy to the extent noted without severe misfires. The terrible fuel economy points to a bad converter...I would say the best option is an experienced shop with emission check equipment. Sorry, but that's the reality.
The simply fact is that running very rich for several days likely at least coated the catalyic converter honeycomb and ruined it's action, at worst it overheated it and melted it.
Badly clogged injectors would likely not cause poor fuel economy to the extent noted without severe misfires. The terrible fuel economy points to a bad converter...I would say the best option is an experienced shop with emission check equipment. Sorry, but that's the reality.
03-24-2012, 08:56 AM
#25
Suggest asking about for a tune-up shop w/ a good diagnostics mechanic. A little due diligence here will pay off.
good luck
03-25-2012, 10:18 PM
#27
Burning Brakes
Thread Starter
Does this show clogged cat? I assume with a clogged cat, you need to run higher RPM's to achieve the same speed?
My 5AT at 60MPH
3rd - 4,000 rpm
4th - 3,100 rpm
5th - 2,100 rpm
My 5AT at 60MPH
3rd - 4,000 rpm
4th - 3,100 rpm
5th - 2,100 rpm
03-25-2012, 11:23 PM
#28
in the 24th and a half...
Not familiar with 5AT rpm relationship.
Clogged/blocked cats tend to cause an inability to rev, but since 70 mph gets you 2400 rpm in a 5AT (see post one final drive swap in other section for picture), that sounds like correct rpms. A cat issue will be performance, especially a unwillingness to rev and/or misfire.
Your base issue is mileage...this means the engine is using more gas for the same performance. If the system isn't running rich, where is it going?
Clogged/blocked cats tend to cause an inability to rev, but since 70 mph gets you 2400 rpm in a 5AT (see post one final drive swap in other section for picture), that sounds like correct rpms. A cat issue will be performance, especially a unwillingness to rev and/or misfire.
Your base issue is mileage...this means the engine is using more gas for the same performance. If the system isn't running rich, where is it going?
03-26-2012, 08:29 AM
#30
I get about 240 miles to a tank if Im doing primarily city driving. with 50/50 I get somewhere around 320. Highway mpg is 29ish. City Im getting about 18-20. Seems like you're getting normal mileage.
Last edited by Stoianoff31; 03-26-2012 at 08:31 AM.
03-26-2012, 11:30 AM
#31
Burning Brakes
Thread Starter
Thanks for the feedback stoianoff. But as I said, its not that i just got this car and trying to figure out the average MPG. I've had this car for nearly 6+ years with 20 miles on the ODO.
The car averaged, through its entire lifetime, anywhere from 36 MPG+ if its highway only all the way down to 22.0 purely city driving with huge hills (upstate new york hills). I've driven both relaxed and spirited and never had my averaged fallen below 22 in the past. After the O2 sensors crapped out and replaced, i struggle to maintain an average of 19.0 mpg (and that's both driving mostly highways and being very cautious about mileage). Just right before the O2 crapped out, I was averaging 24+ with no other changed to the car. Its not whether this is normal, its definitely something wrong/changed with the car.
The car averaged, through its entire lifetime, anywhere from 36 MPG+ if its highway only all the way down to 22.0 purely city driving with huge hills (upstate new york hills). I've driven both relaxed and spirited and never had my averaged fallen below 22 in the past. After the O2 sensors crapped out and replaced, i struggle to maintain an average of 19.0 mpg (and that's both driving mostly highways and being very cautious about mileage). Just right before the O2 crapped out, I was averaging 24+ with no other changed to the car. Its not whether this is normal, its definitely something wrong/changed with the car.
I dont feel much of a pull either. 5th gear is overdrive so I wouldn't expect much. What wheels and tires are you running? Have you done a gas treatment, FI cleaning, etc? What oil are you using?
I get about 240 miles to a tank if Im doing primarily city driving. with 50/50 I get somewhere around 320. Highway mpg is 29ish. City Im getting about 18-20. Seems like you're getting normal mileage.
I get about 240 miles to a tank if Im doing primarily city driving. with 50/50 I get somewhere around 320. Highway mpg is 29ish. City Im getting about 18-20. Seems like you're getting normal mileage.
03-26-2012, 11:56 AM
#32
Hey acn684, how did you know for sure that your O2 sensor crapped out? how much did it cost to get it fixed?
03-26-2012, 01:41 PM
#33
Thanks for the feedback stoianoff. But as I said, its not that i just got this car and trying to figure out the average MPG. I've had this car for nearly 6+ years with 20 miles on the ODO.
The car averaged, through its entire lifetime, anywhere from 36 MPG+ if its highway only all the way down to 22.0 purely city driving with huge hills (upstate new york hills). I've driven both relaxed and spirited and never had my averaged fallen below 22 in the past. After the O2 sensors crapped out and replaced, i struggle to maintain an average of 19.0 mpg (and that's both driving mostly highways and being very cautious about mileage). Just right before the O2 crapped out, I was averaging 24+ with no other changed to the car. Its not whether this is normal, its definitely something wrong/changed with the car.
The car averaged, through its entire lifetime, anywhere from 36 MPG+ if its highway only all the way down to 22.0 purely city driving with huge hills (upstate new york hills). I've driven both relaxed and spirited and never had my averaged fallen below 22 in the past. After the O2 sensors crapped out and replaced, i struggle to maintain an average of 19.0 mpg (and that's both driving mostly highways and being very cautious about mileage). Just right before the O2 crapped out, I was averaging 24+ with no other changed to the car. Its not whether this is normal, its definitely something wrong/changed with the car.
03-26-2012, 02:45 PM
#35
Burning Brakes
Thread Starter
03-26-2012, 02:47 PM
#36
Burning Brakes
Thread Starter
04-06-2012, 08:13 PM
#39
in the 24th and a half...
OK, back to step one, I guess.
Did the mileage fall any BEFORE the O2 failure? You mentioned it was getting 24, but didn't say if that was down. If so, the cause of the O2 failure might be an issue, but since the replacement hasn't failed yet, eh...
So; Low MPG, weak power, anything else?
The air filter can reduce MPG, but not like this. The clue I see is the MPG dropping after perking up on spark plug replacement. Have you pulled one of the new plugs and examined it? Engine tuning and/or emissions issues is the next boogy man to deal with. Without a code being thrown, emissions aren't too far of, but might be off enough to increase consumption a bit...
I'm kinda stumped for now.
Did the mileage fall any BEFORE the O2 failure? You mentioned it was getting 24, but didn't say if that was down. If so, the cause of the O2 failure might be an issue, but since the replacement hasn't failed yet, eh...
So; Low MPG, weak power, anything else?
The air filter can reduce MPG, but not like this. The clue I see is the MPG dropping after perking up on spark plug replacement. Have you pulled one of the new plugs and examined it? Engine tuning and/or emissions issues is the next boogy man to deal with. Without a code being thrown, emissions aren't too far of, but might be off enough to increase consumption a bit...
I'm kinda stumped for now.
04-09-2012, 10:40 AM
#40
Burning Brakes
Thread Starter
The mileage was getting a bit worst after the O2 failure, but not to the point where it was noticeable. I was also doing more city miles during that time. It was basically from 24.0 to Broken O2 which was 14-16.0 MPG, then replaced O2 and sparks back to 19-20.0 MPG
I've just had my emissions checked and had them check for any off codes, nothing they could find.
They couldn't put a finger on it and suggested I remove the roof rack just to see. I tried that, still no improvement in MPG. Infact...it did nothing to the MPG (not even raised it slightly).
I did a vacuum test through the manifold, noticed that it was operating normally like how the tests asked (quick throttle tests, 2,500 rpm hold tests). I did notice however that the needle on idle kept vibrating rapidly between 21-22 Hg. Not sure if i didn't secure something correctly or if that might be an indication of something off with the spark plugs or the ignition coil.
Last 2 thoughts/observances:
1. My tires are potenza pole positions - it was designed to have a "stickier" layer towards the end of the tire life to compensate for having less thread. Perhaps this is creating increased resistance?
2. Dealer suggested that I just run the car hard and see if I can flush out some built up carbon inside. No improvement really...oddly i noticed that when I was in 3rd on the highway doing 60, shifting to 4th increased the average mileage a bit, but shifting to 5th almost seemed like it was doing worst mileage than when it was in 4th. I'm gonna have to test this buy doing 3 runs on the same road on 3/4/5 gear all at the same speed.
Its so frustrating when I know this car can be averaging so many more miles than 20....
I've just had my emissions checked and had them check for any off codes, nothing they could find.
They couldn't put a finger on it and suggested I remove the roof rack just to see. I tried that, still no improvement in MPG. Infact...it did nothing to the MPG (not even raised it slightly).
I did a vacuum test through the manifold, noticed that it was operating normally like how the tests asked (quick throttle tests, 2,500 rpm hold tests). I did notice however that the needle on idle kept vibrating rapidly between 21-22 Hg. Not sure if i didn't secure something correctly or if that might be an indication of something off with the spark plugs or the ignition coil.
Last 2 thoughts/observances:
1. My tires are potenza pole positions - it was designed to have a "stickier" layer towards the end of the tire life to compensate for having less thread. Perhaps this is creating increased resistance?
2. Dealer suggested that I just run the car hard and see if I can flush out some built up carbon inside. No improvement really...oddly i noticed that when I was in 3rd on the highway doing 60, shifting to 4th increased the average mileage a bit, but shifting to 5th almost seemed like it was doing worst mileage than when it was in 4th. I'm gonna have to test this buy doing 3 runs on the same road on 3/4/5 gear all at the same speed.
Its so frustrating when I know this car can be averaging so many more miles than 20....
OK, back to step one, I guess.
Did the mileage fall any BEFORE the O2 failure? You mentioned it was getting 24, but didn't say if that was down. If so, the cause of the O2 failure might be an issue, but since the replacement hasn't failed yet, eh...
So; Low MPG, weak power, anything else?
The air filter can reduce MPG, but not like this. The clue I see is the MPG dropping after perking up on spark plug replacement. Have you pulled one of the new plugs and examined it? Engine tuning and/or emissions issues is the next boogy man to deal with. Without a code being thrown, emissions aren't too far of, but might be off enough to increase consumption a bit...
I'm kinda stumped for now.
Did the mileage fall any BEFORE the O2 failure? You mentioned it was getting 24, but didn't say if that was down. If so, the cause of the O2 failure might be an issue, but since the replacement hasn't failed yet, eh...
So; Low MPG, weak power, anything else?
The air filter can reduce MPG, but not like this. The clue I see is the MPG dropping after perking up on spark plug replacement. Have you pulled one of the new plugs and examined it? Engine tuning and/or emissions issues is the next boogy man to deal with. Without a code being thrown, emissions aren't too far of, but might be off enough to increase consumption a bit...
I'm kinda stumped for now.