LMC Done, Gas Mileage Crashed
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Joined: Aug 2011
Posts: 2
From: texas
LMC Done, Gas Mileage Crashed
Had my Fit LMC recall done about a month ago. Also had oil changed. Before recall work gas mileage about 36 mpg, after just under 29 mpg. Took the Fit back to have it looked at by a roving Honda supertech. No change. This is a real disappointment!!!. Also seems to be noiser(valves). I loved this car before, but not so much now. Has anybody heard about this problem. Honda dealer, San Marcos Honda, does not have a clue. Most driving non-city.
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Joined: Aug 2009
Posts: 3,661
From: Georgia
Member
Joined: Oct 2007
Posts: 2,304
From: Illinois
You have a few things going on 1 new operating conditions and 2 High Heat.
1.Do a ecu reset, Disconnect the battery and do a idle learn procedure. Then I would check the fluids and check air in the tires. Take the car on the highway and from 45-55 mph do a few full throttle passes to 70 and let off the pedal and coast down to 55. It will blow out the carbon off the 4th valve which only operates above 3500rpm and that will set the ecu with new perimeters.
2. With the High intake temps about 10 percent of the fuel vaporizes before the burn and dissipates, which means more fuel is needed. There might be knock retard too which higher octane will help. Higher octane helps the engine run more efficient and typically gets better mpg. Typically a small bore motor doesn't need that high of octane because the flame front has a small space to a complete burn but at loads over 70 percent it can run as rich as 11 to 1 fuel air. Premium allows close loop(14.6 A/F) at loads over 70 percent.
A/C uses 20/25 percent more fuel too. We have had Hot weather up here with high humidity and I try not to use the A/C. I usually turn it on for a few minutes and then turn it off until it gets too hot inside. Its seems to work for me I am getting 43 mpg.
1.Do a ecu reset, Disconnect the battery and do a idle learn procedure. Then I would check the fluids and check air in the tires. Take the car on the highway and from 45-55 mph do a few full throttle passes to 70 and let off the pedal and coast down to 55. It will blow out the carbon off the 4th valve which only operates above 3500rpm and that will set the ecu with new perimeters.
2. With the High intake temps about 10 percent of the fuel vaporizes before the burn and dissipates, which means more fuel is needed. There might be knock retard too which higher octane will help. Higher octane helps the engine run more efficient and typically gets better mpg. Typically a small bore motor doesn't need that high of octane because the flame front has a small space to a complete burn but at loads over 70 percent it can run as rich as 11 to 1 fuel air. Premium allows close loop(14.6 A/F) at loads over 70 percent.
A/C uses 20/25 percent more fuel too. We have had Hot weather up here with high humidity and I try not to use the A/C. I usually turn it on for a few minutes and then turn it off until it gets too hot inside. Its seems to work for me I am getting 43 mpg.
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Joined: Aug 2009
Posts: 3,661
From: Georgia
A/C uses 20/25 percent more fuel too. We have had Hot weather up here with high humidity and I try not to use the A/C. I usually turn it on for a few minutes and then turn it off until it gets too hot inside. Its seems to work for me I am getting 43 mpg.
2. With the High intake temps about 10 percent of the fuel vaporizes before the burn and dissipates, which means more fuel is needed.
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New Member
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From: texas
Silverbullet, what is a idle learn procedure. Latest fillup was with a higher octane, can't see any difference. Tires are OK. Temps are really high now, 104 expected today, but was high before before the LMS fix. Goin to Houston today, curious what the mileage will be, about 200 miles.
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Joined: Aug 2009
Posts: 3,661
From: Georgia
Learn idle procedure? Isn't that what the dealer does by starting the car and letting it run a few minutes so the ECU adjusts idle speed? Yup, step 39 in the Pre Delivery Inspection. It's linked from this thread.
Hot temps, other than causing the A/C to work more, won't decrease your MPG. The hot air is less dense will cause less fuel to be burned as the ECU adjusts. This will result in less power, but MPG will not suffer. Anecdotally, running the A/C reduces MPG anywhere from 0 to a couple MPG.
A higher octane rated fuel has not been shown to increase MPG in this, or any car whose manufacturer does not recommend higher than 87.
If your car has a lot of miles on it (over 100K?) carbon deposits might be an issue. The GE Fit's "vtec" is electronically actuated and doesn't require a specific RPM to come into play. Executing an Italian tuneup might be fun, but I don't think it's called for.
I don't notice a difference between winter and summer MPG here in Atlanta running regular fuel.
Either some operating parameter is different (different routes, drivers) or there is a mechanical issue (tire pressure, alignment, valve clearance etc). Rule out as many variables as you can. It's possible the valve adjustment the dealer performed after the lost motion springs were changed was not optimal.
Hot temps, other than causing the A/C to work more, won't decrease your MPG. The hot air is less dense will cause less fuel to be burned as the ECU adjusts. This will result in less power, but MPG will not suffer. Anecdotally, running the A/C reduces MPG anywhere from 0 to a couple MPG.
A higher octane rated fuel has not been shown to increase MPG in this, or any car whose manufacturer does not recommend higher than 87.
If your car has a lot of miles on it (over 100K?) carbon deposits might be an issue. The GE Fit's "vtec" is electronically actuated and doesn't require a specific RPM to come into play. Executing an Italian tuneup might be fun, but I don't think it's called for.
I don't notice a difference between winter and summer MPG here in Atlanta running regular fuel.
Either some operating parameter is different (different routes, drivers) or there is a mechanical issue (tire pressure, alignment, valve clearance etc). Rule out as many variables as you can. It's possible the valve adjustment the dealer performed after the lost motion springs were changed was not optimal.
Member
Joined: Oct 2007
Posts: 2,304
From: Illinois
Learn idle procedure? Isn't that what the dealer does by starting the car and letting it run a few minutes so the ECU adjusts idle speed? Yup, step 39 in the Pre Delivery Inspection. It's linked from this thread.
Hot temps, other than causing the A/C to work more, won't decrease your MPG. The hot air is less dense will cause less fuel to be burned as the ECU adjusts. This will result in less power, but MPG will not suffer. Anecdotally, running the A/C reduces MPG anywhere from 0 to a couple MPG.
A higher octane rated fuel has not been shown to increase MPG in this, or any car whose manufacturer does not recommend higher than 87.
If your car has a lot of miles on it (over 100K?) carbon deposits might be an issue. The GE Fit's "vtec" is electronically actuated and doesn't require a specific RPM to come into play. Executing an Italian tuneup might be fun, but I don't think it's called for.
I don't notice a difference between winter and summer MPG here in Atlanta running regular fuel.
Either some operating parameter is different (different routes, drivers) or there is a mechanical issue (tire pressure, alignment, valve clearance etc). Rule out as many variables as you can. It's possible the valve adjustment the dealer performed after the lost motion springs were changed was not optimal.
Hot temps, other than causing the A/C to work more, won't decrease your MPG. The hot air is less dense will cause less fuel to be burned as the ECU adjusts. This will result in less power, but MPG will not suffer. Anecdotally, running the A/C reduces MPG anywhere from 0 to a couple MPG.
A higher octane rated fuel has not been shown to increase MPG in this, or any car whose manufacturer does not recommend higher than 87.
If your car has a lot of miles on it (over 100K?) carbon deposits might be an issue. The GE Fit's "vtec" is electronically actuated and doesn't require a specific RPM to come into play. Executing an Italian tuneup might be fun, but I don't think it's called for.
I don't notice a difference between winter and summer MPG here in Atlanta running regular fuel.
Either some operating parameter is different (different routes, drivers) or there is a mechanical issue (tire pressure, alignment, valve clearance etc). Rule out as many variables as you can. It's possible the valve adjustment the dealer performed after the lost motion springs were changed was not optimal.
http://www.fuelcertification.com/doc...gine_Knock.pdf
Carbon deposits are not just the pistons, you have valves and chamber deposits too.
Also the Fit use a hydraulic itvec. ‪iVTEC_128sec_hi.flv‬‏ - YouTube
Last edited by SilverBullet; Aug 5, 2011 at 09:44 PM.
Member
Joined: Aug 2009
Posts: 3,661
From: Georgia
There is no need for premium gas in our Fits.
This just shows you have read the advertising from the major oil companies.
From your own reference:
Pretty good manual. It may have some bias as it's paid for by ethanol producers, but I don't see any.
Here's an excerpt from page 4:
Edit: We were both wrong on the activation of i-vtec on GE8s. According to this thread it's controlled by ECU and a solenoid (which uses hydraulics to engage) but the threshold is 5,400 RPM.
This just shows you have read the advertising from the major oil companies.
From your own reference:
I would check the tire pressure and oil level, then try premium. The low mpg your car is getting sounds like knock retard. http://www.goldeagle.com/UserFiles/f...dated_Logo.pdf
Here's an excerpt from page 4:
A number of myths about octane have grown over the
years. There is a widespread perception that the greater the
octane the better the performance. However, once enough
octane is supplied to prevent engine knock, there is little, if
any, performance improvement. One exception to this would
be in vehicles equipped with knock sensors. In these vehicles,
if octane is insufficient, the computer will retard the timing to
limit engine knock. If the vehicle is operating in the “knock
limiting” mode (retarded timing), using a higher octane fuel will
allow timing to be advanced, resulting in some level of
performance increase. However, even in these vehicles,
tests have shown that there is no perceptible performance
improvement from using a fuel of higher octane than that
recommended by the vehicle manufacturer.
Another myth is that using a higher octane fuel will result
in improved fuel economy (increased miles per gallon). Octane
is nothing more than a measure of anti-knock quality.
Fuel economy is determined by a number of variables including
the energy content of the fuel. Some premium grades of
fuel may contain components which increase energy content.
In those cases, fuel economy may improve slightly as a result
of higher energy content, but not as a result of the higher
octane. Two fuels of identical octane could have different
energy content due to compositional differences
years. There is a widespread perception that the greater the
octane the better the performance. However, once enough
octane is supplied to prevent engine knock, there is little, if
any, performance improvement. One exception to this would
be in vehicles equipped with knock sensors. In these vehicles,
if octane is insufficient, the computer will retard the timing to
limit engine knock. If the vehicle is operating in the “knock
limiting” mode (retarded timing), using a higher octane fuel will
allow timing to be advanced, resulting in some level of
performance increase. However, even in these vehicles,
tests have shown that there is no perceptible performance
improvement from using a fuel of higher octane than that
recommended by the vehicle manufacturer.
Another myth is that using a higher octane fuel will result
in improved fuel economy (increased miles per gallon). Octane
is nothing more than a measure of anti-knock quality.
Fuel economy is determined by a number of variables including
the energy content of the fuel. Some premium grades of
fuel may contain components which increase energy content.
In those cases, fuel economy may improve slightly as a result
of higher energy content, but not as a result of the higher
octane. Two fuels of identical octane could have different
energy content due to compositional differences
Last edited by Steve244; Aug 5, 2011 at 11:17 PM.
Member
Joined: Oct 2007
Posts: 2,304
From: Illinois
Steve, You only read what you want and disregard everything that doesn't agree with your perceived notions. In that article it also explains octane requirement for a 10.4 to 1 compression motor which is 100 ron fuel.
Quote:
Most vehicles give satisfactory performance on the
recommended octane-rated fuel. But in some cases, using
the fuel specified will not guarantee that a vehicle will operate
knock-free, even when properly tuned. There can be significant differences among engines, even of the same make and
model, due to normal production variations.
The actual loss of power and damage to an automobile
engine, due to knocking, is generally not significant unless the
intensity becomes severe. Heavy and prolonged knocking,
however, may cause severe damage to the engine.
Whether or not an engine knocks is dependent upon the
octane quality of the fuel and the Octane Number Requirement (ONR) of the engine. The ONR is affected by various
engine design factors and in-use conditions.
Quote:
The air/fuel ratio
also effects ONR with maximum octane requirement occurring at an air/fuel ratio of about 14.7:1. Enriching or enleaning
from this ratio generally reduces octane requirement. Combustion temperatures are also a factor with higher combustion
temperatures increasing ONR.
Quote:
Most vehicles give satisfactory performance on the
recommended octane-rated fuel. But in some cases, using
the fuel specified will not guarantee that a vehicle will operate
knock-free, even when properly tuned. There can be significant differences among engines, even of the same make and
model, due to normal production variations.
The actual loss of power and damage to an automobile
engine, due to knocking, is generally not significant unless the
intensity becomes severe. Heavy and prolonged knocking,
however, may cause severe damage to the engine.
Whether or not an engine knocks is dependent upon the
octane quality of the fuel and the Octane Number Requirement (ONR) of the engine. The ONR is affected by various
engine design factors and in-use conditions.
Quote:
The air/fuel ratio
also effects ONR with maximum octane requirement occurring at an air/fuel ratio of about 14.7:1. Enriching or enleaning
from this ratio generally reduces octane requirement. Combustion temperatures are also a factor with higher combustion
temperatures increasing ONR.
Last edited by SilverBullet; Aug 5, 2011 at 11:23 PM.
Member
Joined: Oct 2008
Posts: 577
From: NJ
Mazda is coming out with Skyactiv engines, with a 13:1 compression ratio designed to run on 87 octane.
Using anything but 87 octane in a Fit is just pouring money into the oil companies. Just don't use some no name brand.
Using anything but 87 octane in a Fit is just pouring money into the oil companies. Just don't use some no name brand.
Member
Joined: Aug 2009
Posts: 3,661
From: Georgia
Bullet, You only read what you want and disregard everything that doesn't agree with your preconceived notions.
The recommended octane rating for our little economy cars is 87. It's in the manual.
Here it is (2009 page 198):
Show me where any manufacturer states any of these cars will run better, either power or MPG with higher octane. Show me any enthusiast magazine that states these cars will run better on higher octane.
Show me any article that states higher octane will benefit any car that neither recommends or requires it.
Show me any set of fuel consumption logs that shows better MPG on premium in a car, any car, whose manufacturer neither recommends or requires premium.
Guess what: I'll read it. Then we can discuss it. (But don't post oil company advertisements and expect me to take you seriously. And don't post lengthy papers that have nothing to do with the topic. If you do, please quote the section you think is relevant and give the page number, thanks).
I realize the placebo effect is strong with premium gas. You've got the sexy ads. You've got the desire to go fast and far. And it's a simple modification, just fill'er up. But that's all it is, a placebo effect.
The OP has probably wandered off and shot himself by now, but even he said he didn't get any bang from his bucks he spent on premium. Are you ignoring him too?
From your excerpt above:
The recommended octane rating for our little economy cars is 87. It's in the manual.
Here it is (2009 page 198):
Fuel Recommendation
Your vehicle is designed to operate
on unleaded gasoline with a pump
octane number of 87 or higher.
Honda did a great job engineering a 10:1 compression ratio that runs on regular gas. Well, so did Ford (Fiesta is 11:1) and Toyota (Yaris is 10.5:1).Your vehicle is designed to operate
on unleaded gasoline with a pump
octane number of 87 or higher.
Show me where any manufacturer states any of these cars will run better, either power or MPG with higher octane. Show me any enthusiast magazine that states these cars will run better on higher octane.
Show me any article that states higher octane will benefit any car that neither recommends or requires it.
Show me any set of fuel consumption logs that shows better MPG on premium in a car, any car, whose manufacturer neither recommends or requires premium.
Guess what: I'll read it. Then we can discuss it. (But don't post oil company advertisements and expect me to take you seriously. And don't post lengthy papers that have nothing to do with the topic. If you do, please quote the section you think is relevant and give the page number, thanks).
I realize the placebo effect is strong with premium gas. You've got the sexy ads. You've got the desire to go fast and far. And it's a simple modification, just fill'er up. But that's all it is, a placebo effect.
The OP has probably wandered off and shot himself by now, but even he said he didn't get any bang from his bucks he spent on premium. Are you ignoring him too?
From your excerpt above:
The actual loss of power and damage to an automobile
engine, due to knocking, is generally not significant unless the
intensity becomes severe.
I agree, if your car has severe engine knock, you should switch to a higher octane. (What are they talking about, 1970s automobiles? Performance cars? Who here has severe engine knock? Raise your hands!)
engine, due to knocking, is generally not significant unless the
intensity becomes severe.
Last edited by Steve244; Aug 5, 2011 at 11:49 PM.
Member
Joined: Oct 2007
Posts: 2,304
From: Illinois
I never said the Fit requires premium, only that premium can give better power and mpg.
There are a lot of variables and premium always gave me more mpg, winter aside in the coldest part but then I use mid grade. My car is rated 39 highway and I am getting 43 mpg in mixed driving at 70+ highway speeds and the rest city averaging 43mph on the tank. There are others that are using premium or mid grade with the same results compared to lower mpg and power on regular.
There are a lot of variables and premium always gave me more mpg, winter aside in the coldest part but then I use mid grade. My car is rated 39 highway and I am getting 43 mpg in mixed driving at 70+ highway speeds and the rest city averaging 43mph on the tank. There are others that are using premium or mid grade with the same results compared to lower mpg and power on regular.
Member
Joined: Aug 2009
Posts: 3,661
From: Georgia
I never said the Fit requires premium, only that premium can give better power and mpg.
There are a lot of variables and premium always gave me more mpg, winter aside in the coldest part but then I use mid grade. My car is rated 39 highway and I am getting 43 mpg in mixed driving at 70+ highway speeds and the rest city averaging 43mph on the tank. There are others that are using premium or mid grade with the same results compared to lower mpg and power on regular.
There are a lot of variables and premium always gave me more mpg, winter aside in the coldest part but then I use mid grade. My car is rated 39 highway and I am getting 43 mpg in mixed driving at 70+ highway speeds and the rest city averaging 43mph on the tank. There are others that are using premium or mid grade with the same results compared to lower mpg and power on regular.
Member
Joined: Oct 2007
Posts: 2,304
From: Illinois
Its basically diesel technology in gasoline form which is cool in itself.
Side note that the Fits Cat is right off the exhaust so there must be a lot of heat that causes knock. The only reason Honda says 87 is due to oil squirters that spray oil underneath the pistons but deposits will eventually build up around the spray causing hot spots.
Member
Joined: Oct 2008
Posts: 577
From: NJ
Might give it a shot and try it out - will have to use premium soon enough anyways when the Fit goes.
Member
Joined: Oct 2007
Posts: 2,304
From: Illinois
So if I understand correctly what you're saying - premium will result in less knock (improved power) and a cleaner engine for the Fit? And based on some other discussions, could lead to a 10% increase in fuel economy too?
Might give it a shot and try it out - will have to use premium soon enough anyways when the Fit goes.
Might give it a shot and try it out - will have to use premium soon enough anyways when the Fit goes.
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