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pgwerner

Just Bought '05 Corolla - Mileage Is Awful!

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Since Bikeman says that it is not difficult to change the ECU, you might actually want to swap your ECU and see if your hypothesis is true.

 

What comments do the dealers have on this topic?

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Abnormal gas cunsumption is a common complaint for 05 auto corollas. I'm not sure about manuals, but if you search yahoo auto or other corolla forums, there are two distinct groups - one getting expected/above expected gas mileage, the other getting around ~25 mpg. This issue has been bothering me for a long time, since my car is 05 auto too and I get arounf 25 mpg. No one seems to know exactly how to explain such two distinctive groups. I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs. One from Denso and the other from Delco. Corollas get equipped with either the ECU from Denso or Delco. It might be possible that one of these ECUs is causing bad gas mileage. Unfortunately, the only way to tell what ecu you got is to physically check by taking off the glove box compartment.

 

Interesting idea about the ECUs. According to my info, MT is always Denso, AT is either Denso or Delco. Furthermore, some Delco ECUs are non-reprogrammable.

I also have suboptimal MPG, get only 30 on hwy and 27 city with gentle driving. I will check my ECU and report back.

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Warming a car up is unnecessary - it doesn't decrease engine wear, creates extra pollution, and will reduce MPG. Engine wear comes from the cylinders moving, not from driving the car (and the cylinders cycle regardless of whether the car is moving or idling). This type of engine wear is unavoidable.

 

On the road, even in cold weather (20s & 30s), my 2004 begins warming within 1 mile.

 

My manual 2004 gets excellent mileage: 40-42 summer, 37-39 winter. In San Francisco, I could understand an automatic getting particularly poor mileage because of the many hills, but 24 seems very low.

 

One of the biggest contributers to driver induced poor mileage is rate of acceleration from stops. (yesterday driving to work, a Prius in front of me shot forward at green lights. I'm sure he's wondering "why do I get terrible mileage?"). Aggressive driving has become so standard, that EPA is even considering changing MPG testing to account for it.

 

As has been suggested, I keep my tires firm and this contributes to the good mileage. I use the defroster and a/c minimally.

 

Finally, if there are problems with your ECM, emission testing should find this (if poor MPG is from incomplete combustion of fuel, this will create increased CO and hydrocarbon emissions.) If the engine is functioning normally & passes the emissions check, the problem resides elsewhere.

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Warming a car up is unnecessary - it doesn't decrease engine wear, creates extra pollution, and will reduce MPG. Engine wear comes from the cylinders moving, not from driving the car (and the cylinders cycle regardless of whether the car is moving or idling). This type of engine wear is unavoidable.

 

On the road, even in cold weather (20s & 30s), my 2004 begins warming within 1 mile.

 

My manual 2004 gets excellent mileage: 40-42 summer, 37-39 winter. In San Francisco, I could understand an automatic getting particularly poor mileage because of the many hills, but 24 seems very low.

 

One of the biggest contributers to driver induced poor mileage is rate of acceleration from stops. (yesterday driving to work, a Prius in front of me shot forward at green lights. I'm sure he's wondering "why do I get terrible mileage?"). Aggressive driving has become so standard, that EPA is even considering changing MPG testing to account for it.

 

As has been suggested, I keep my tires firm and this contributes to the good mileage. I use the defroster and a/c minimally.

 

Finally, if there are problems with your ECM, emission testing should find this (if poor MPG is from incomplete combustion of fuel, this will create increased CO and hydrocarbon emissions.) If the engine is functioning normally & passes the emissions check, the problem resides elsewhere.

 

I'm not the original poster but your advice is insulting. If you reread the very first post, you will find the poster used to get 30mpg in old Corolla and is getting 24mpg in the new one WITH THE SAME DRIVING STYLE.

 

My corolla also has suboptimal MPG REGARDLESS of driving style. I get 27mpg in city with regular driving and 28mpg with super duper granny driving (keeping RPM under 2000). I also get disapointing 30-31mpg on hwy. So, I'm very sympathetic to the original poster's cause as I went through the same disappointment. The car now has 30000 miles and it's the same, so don't count on improving. BTW, I keep tires inflated to 36 psi and observe all precausions to save fuel.

 

Clearly, some corollas are not as efficient as others and it would be nice to discover the root cause. Blaiming on the driver is contraproductive.

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When one buys a used car, is there a simple way to tell whether a previous owner has put in a "performance chip" that replaces the stock computer? Can the computer ID be read from some diagnostic terminal? Or do you have to take things apart to see what is there?

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I believe owner's manuals recommend at least one minute after start-up before proceeding just to get the oil and fluids circulating. It sounds logical to me to help the moving components last longer.

Edited by Bikeman982

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There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

Edited by Bikeman982

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There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

Yes, you're right. I am not trying to argue with anyone, but how do you explain an almost brand-new 05 corollas, and with my and many other cases who drive conservatively, with no long warm-up in mornings, and who kept thier tires inflated above 30psi, get nowhere close to expected gas mileage? Even with normal highway driving, why is there one group who gets sub-par gas mileage while the other group with almost identical driving gets superb gas mileage? Some people argue that EPA or whatever the organization is testing gas mileage use a controlled condition so the actual gas mileage is lower. If so, how do you explain a group of people who gets expected and in some cases above expected gas mileage with a same car? Why is there such a distinct, clearly identifyable groups each with a common, distinctive trait- gas guzzlers and gas sippers? Can normal human error create such big of a difference? Search yahoo auto and other corolla forums and read what owners say about thier corolla's gas mieage- clearly its obvious that people either complain or praise about thier gas mileage.

 

.... I appologize, I just had to write down every question I have because the main reason I got a corolla is because of its excellent gas mileage according to the sticker. I feel let down and dissapointed because no matter how conservatively I drive, the best i got so far was 28 mpg on highway, without speeding or flooring every minute. I am more inclined to drive conservatively just to try to achieve such a great gas mileage that so many people with same corollas do, which never seems to happen in case of my car no matter my effort. My dealer declined my complaint about my gas mileage and said "its normal". I am suspecting more of a mechanical factor infulencing the gas mileage rather than human error. This is why I asked about the ECU. Thanks for reading.

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There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

Yes, you're right. I am not trying to argue with anyone, but how do you explain an almost brand-new 05 corollas, and with my and many other cases who drive conservatively, with no long warm-up in mornings, and who kept thier tires inflated above 30psi, get nowhere close to expected gas mileage? Even with normal highway driving, why is there one group who gets sub-par gas mileage while the other group with almost identical driving gets superb gas mileage? Some people argue that EPA or whatever the organization is testing gas mileage use a controlled condition so the actual gas mileage is lower. If so, how do you explain a group of people who gets expected and in some cases above expected gas mileage with a same car? Why is there such a distinct, clearly identifyable groups each with a common, distinctive trait- gas guzzlers and gas sippers? Can normal human error create such big of a difference? Search yahoo auto and other corolla forums and read what owners say about thier corolla's gas mieage- clearly its obvious that people either complain or praise about thier gas mileage.

 

.... I appologize, I just had to write down every question I have because the main reason I got a corolla is because of its excellent gas mileage according to the sticker. I feel let down and dissapointed because no matter how conservatively I drive, the best i got so far was 28 mpg on highway, without speeding or flooring every minute. I am more inclined to drive conservatively just to try to achieve such a great gas mileage that so many people with same corollas do, which never seems to happen in case of my car no matter my effort. My dealer declined my complaint about my gas mileage and said "its normal". I am suspecting more of a mechanical factor infulencing the gas mileage rather than human error. This is why I asked about the ECU. Thanks for reading.

Well, besides the differences in climates at their locations, there is also individual vehicle characteristics (even though they may seem identical). I don't think there is any clear-cut distinctions. I think there is probably a variety of people who (not all are here to post) get a range of mileage per gallon figures.

Not that anyone would possibly do it, but some could be slightly exagerating?

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There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

Yes, you're right. I am not trying to argue with anyone, but how do you explain an almost brand-new 05 corollas, and with my and many other cases who drive conservatively, with no long warm-up in mornings, and who kept thier tires inflated above 30psi, get nowhere close to expected gas mileage? Even with normal highway driving, why is there one group who gets sub-par gas mileage while the other group with almost identical driving gets superb gas mileage? Some people argue that EPA or whatever the organization is testing gas mileage use a controlled condition so the actual gas mileage is lower. If so, how do you explain a group of people who gets expected and in some cases above expected gas mileage with a same car? Why is there such a distinct, clearly identifyable groups each with a common, distinctive trait- gas guzzlers and gas sippers? Can normal human error create such big of a difference? Search yahoo auto and other corolla forums and read what owners say about thier corolla's gas mieage- clearly its obvious that people either complain or praise about thier gas mileage.

 

.... I appologize, I just had to write down every question I have because the main reason I got a corolla is because of its excellent gas mileage according to the sticker. I feel let down and dissapointed because no matter how conservatively I drive, the best i got so far was 28 mpg on highway, without speeding or flooring every minute. I am more inclined to drive conservatively just to try to achieve such a great gas mileage that so many people with same corollas do, which never seems to happen in case of my car no matter my effort. My dealer declined my complaint about my gas mileage and said "its normal". I am suspecting more of a mechanical factor infulencing the gas mileage rather than human error. This is why I asked about the ECU. Thanks for reading.

Well, besides the differences in climates at their locations, there is also individual vehicle characteristics (even though they may seem identical). I don't think there is any clear-cut distinctions. I think there is probably a variety of people who (not all are here to post) get a range of mileage per gallon figures.

Not that anyone would possibly do it, but some could be slightly exagerating?

 

 

Bikeman, you are doing exactly what DWC was trying to do, fixing the blame on the owner.

The facts are simple, the guy used to get 30 mph in 95 corolla and gets 24 mph in 05 corolla. This is not trivial, 20% loss with same driving style. Some corollas have a hidden flow making them gas guzlers. My 03 not only had less than average mpg but also sulfur smell, signs of running too rich. Yet, there are no MIL, no codes, and all sensors seem to be working well on the OBD2 scanner.

 

Bikeman, if you have a good explanation for this anomaly, please let us know.

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There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

Yes, you're right. I am not trying to argue with anyone, but how do you explain an almost brand-new 05 corollas, and with my and many other cases who drive conservatively, with no long warm-up in mornings, and who kept thier tires inflated above 30psi, get nowhere close to expected gas mileage? Even with normal highway driving, why is there one group who gets sub-par gas mileage while the other group with almost identical driving gets superb gas mileage? Some people argue that EPA or whatever the organization is testing gas mileage use a controlled condition so the actual gas mileage is lower. If so, how do you explain a group of people who gets expected and in some cases above expected gas mileage with a same car? Why is there such a distinct, clearly identifyable groups each with a common, distinctive trait- gas guzzlers and gas sippers? Can normal human error create such big of a difference? Search yahoo auto and other corolla forums and read what owners say about thier corolla's gas mieage- clearly its obvious that people either complain or praise about thier gas mileage.

 

.... I appologize, I just had to write down every question I have because the main reason I got a corolla is because of its excellent gas mileage according to the sticker. I feel let down and dissapointed because no matter how conservatively I drive, the best i got so far was 28 mpg on highway, without speeding or flooring every minute. I am more inclined to drive conservatively just to try to achieve such a great gas mileage that so many people with same corollas do, which never seems to happen in case of my car no matter my effort. My dealer declined my complaint about my gas mileage and said "its normal". I am suspecting more of a mechanical factor infulencing the gas mileage rather than human error. This is why I asked about the ECU. Thanks for reading.

Well, besides the differences in climates at their locations, there is also individual vehicle characteristics (even though they may seem identical). I don't think there is any clear-cut distinctions. I think there is probably a variety of people who (not all are here to post) get a range of mileage per gallon figures.

Not that anyone would possibly do it, but some could be slightly exagerating?

 

 

Bikeman, you are doing exactly what DWC was trying to do, fixing the blame on the owner.

The facts are simple, the guy used to get 30 mph in 95 corolla and gets 24 mph in 05 corolla. This is not trivial, 20% loss with same driving style. Some corollas have a hidden flow making them gas guzlers. My 03 not only had less than average mpg but also sulfur smell, signs of running too rich. Yet, there are no MIL, no codes, and all sensors seem to be working well on the OBD2 scanner.

 

Bikeman, if you have a good explanation for this anomaly, please let us know.

I am merely presenting possibilities. Without actually having the car and checking it out, I can only speculate on the cause, based on the description of the symptoms. There are similar cases presented by others and causes have not been definitively identified. The car (by your description) has had a seemingly unexplainable significant decrease in efficiency. I am not putting any blame on any owner, I am just stating that driving characteristics do have an effect on the gas mileage. That does not rule out the possibility that there is a mechanical, electrical, or other malfunction with one or several components. If there is no MIL, does that mean it is operating within the design parameters? The dealers would probably say that it is. They can thoroughly check everything out (at great expense to the owner) and come up with "nothing abnormal". We who do the daily driving of our vehicles can notice things like reduction in efficiency, while testing can only verify everything is functioning as designed. Most repair places will follow fault isolation methods and change something based on the results, which may or may not actually fix the problem. Meanwhile we have to accept the results, or continue to spend money and time trying to get it fixed. We all have the same options, some of them better than others. Hope this helps.

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I think the problem is the car. not the driver. maybe it is the ECU mentioned long time ago in this thread.

 

That may very well be the case and to verify it, the ECU would have to be changed and all other conditions remain the same, to be a valid test.

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Interesting idea about the ECUs. According to my info, MT is always Denso, AT is either Denso or Delco. Furthermore, some Delco ECUs are non-reprogrammable.

I also have suboptimal MPG, get only 30 on hwy and 27 city with gentle driving. I will check my ECU and report back.

Maybe we should test this ECU theory. I have a manual so I assume I have the Denso. I get an excellent 37mpg combined. Is there anyone with a manual that is getting really bad mileage?

 

For autos, can some people report which ECU they have and what mileage they're getting?

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