Car getting VERY low MPG? Ideas anyone?

[Kevbo 81]

Hi everyone  I have a 2001 Camry 4 cylinder with about 83,000 miles on the engine (4 cylinder) that I bought used back in June of last year. I have not been overall too excited about my MPG and it seems to have gotten worse...right now I am averaging only 16 MPG!

When I got the car I replaced the spark plugs with NGK Iridium plugs and I also put in new wires and replaced the air filter, so I cannot imagine that any of these above would be the problem?

I keep all of my tires at 35 PSI equally balanced as well. So I don't believe this is the issue either?

For about two weeks my check engine light was on so I took the car to advanced auto to have it analyzed. They said that the engine was "not running efficient" but obviously could not tell exactly. As of right now my check engine light has been off for over a week and everything seems normal? Might I have gotten bad tank full of gas? The gas cap was on tight.

I wanted to check in with all of you before I scheduled a trip to the dealer. Now that the check engine light is off, I have no reason to make an appointment as the engine's performance is normal I just have such a LOW MPG I feel like I am driving a truck!!

Anyone have any ideas? Things to try? Possible problems?

Thanks so much in advance!

Edited March 18, 2013 by Kevbo

[posifour11 723]

Air intake clogged? Injectors? Bodies in the trunk?

[Kevbo 81]

I have a custom air intake that is supposed to boost MPG since the air filter is not confined to an air filter box and I regularly add seafoam to my gas tank every 3,000 miles to clean injectors? Could they still be clogged? Could a clogged fuel filter cause MPG problems?

Edited March 18, 2013 by Kevbo

[rmaynard 16,289]

The ethanol in the gas, as well as oxygenation that is done in the winter months, will decrease mileage significantly. 

 

However, if the check engine light was on for awhile, I would take it somewhere other than Advance Auto Parts for a checkup. My independent auto service facility can analyze a code much deeper. There may be a bad ignition module or some other device that is causing the engine to not run efficiently. 

 

My Subaru was throwing intermittent codes saying that #1, 2, 3, & 4 cylinders were not firing correctly. Turned out to be a build-up of corrosion on top of the battery between the + terminal and the hold-down strap. How that caused misfiring is a mystery, but when I Googled it, I found that others were having the same problem.

 

Bottom line, take your car to a reputable shop to have the problem analyzed.    

 

 

[JBow 8]

If we had the codes we could most likely help you.  Some cheap handheld scanners don't read them very well.  Even though the CEL went out the trouble codes should still be there unless they were cleared or you have done a battery disconect.  For what its worth those aftermarket intake tubes and cone style air filters are not an improvment.  Your money could be better spent elswhere.  Pull the codes and come back with some DTC numbers. The term "not running efficient" tells me nothing.

 

Jack..

[squonk 43,701]

Do like Bob said. My guess would be a misfire problem or an O2 sensor is going out.Take it to a shop. All an auto parts store can do is scan it tell you what the code is and then sell you every part in the bldg. related to the code.

[Save Old Iron 1,571]

fuel regulator, pre cat o2 sensor, intake air temp sensor - one of these sensors could be commanding the fuel injectors to stay open at an abnormal pulse time - come to think of it, the throttle position sensor could be a culprit too.

 

you could have knocked a wire off a sensor during spark plug replacement 

 

better to get it scanned quickly, the extra fuel vapors flowing thru the catalytic converter can ruin the cat in a few hundred miles of driving

[puddlejumper 67]

If you are going to take it to a shop for a better reading of the codes do it before cleaning the battery cables as bob mentioned was causing his problems above, because it will erase the error codes when you unhook the battery. Its not a big deal you just may have to drive it awhile for the error codes to reestablish themselves. I had a explorer once that a shop wanted to replace my transmission in because it was kicking in and out of overdrive and the codes showed a problem with the tranny, I replaced the battery cables and cured the problem. Talk about saving a dollar.

[nylyon-(Admin) 7,878]

As mentioned, you need to get the code.  I can tell you with 100% certainty that MOST inexpensive code readers do NOT read manufacturer specific PID's.  You need to get it read by a professional reader (or buy one yourself).  

 

Once you know what the code(s) are you can diagnose the issue.  The good news is that the CEL is on, making the diagnosis a little easier.

[6wheeler 669]

Everyone always says they put in the big dollar plugs. Expensive wires and a "high flow" air filter. Shouldn't that fix it? Well, it doesn't. As a few members said earlier, there are several pieces in this puzzle. I, myself would go for the fuel filter first. Reason being is. A plugged filter or even partially plugged, changes the fuel pressure to the regulator. So now the computer tells the other sensors, "I need more pressure". So in turn, they start  sending signals "more fuel" Which opens the regulator to flow more fuel but its not pressurized properly and the injectors dump it in a less vaporized manner which lessens burn which lessens the engines ability to be "efficient". Then, the O2 sensor sends a signal back to the computer saying "we have a lean burn situation here", so the computer tries to adjust again. It is a vicious circle.The O2 sensor or the MAF sensor or even a faulty temp sensor can wreak havoc on an EFI system. Strangely enough, even a bad or corroded plug on any one of the sensors could be giving a false reading. I don't go to a shop very often and do not own a diagnostic computer. I simply follow the general rules of an internal combustion engine. As my High School shop teacher always taught us, FFA - Fuel, Fire and Air, is all they need to run. Simple theory, but it works.

[KC9KAS 4,744]

Wife had a 1999 Camry with 180,000 miles (4 cylinder) and it still got 30 MPG.

She traded it for a brand new Hyundi that is rough riding and only gets 28 MPG (with me driving....I get better MPG's in her car than she does), and the dealer said "Oh this will get 35 MPG easy".....Yeah right, and I'm an astronaut!

[squonk 43,701]

Worked on Fuel injected cars for 20 years. Never seen a plugged or restricted filter cause an engine to burn more fuel. Fuel regulators usually are controlled by engine vacuum. The less vac the more pressure. The engine would have to be running pretty crappy for a pressure increase. The the computer will have to open the injectors longer to actually increase the amount of fuel going to the cylinders. I still say it a lazy O2 sensor telling the computer it's lean and adding fuel trim. You need a high dollar scanner to see this. 9 times out of 10 if the engine is pretty much running ok but has bad mileage it's O2 related.

[Save Old Iron 1,571]

. Fuel regulators usually are controlled by engine vacuum. The less vac the more pressure. The engine would have to be running pretty crappy for a pressure increase.

A regulator stuck closed would ignore any vacuum modulation and over pressure the injectors. Not too many cars throw a code for fuel pressure. Also, a pinhole leak in the fuel reg diaphragm could suck fuel into the vacuum system. A piece of clear tubing spliced onto the regulator vac port will show if fuel is being sucked thru the regulator into the engine.

[squonk 43,701]

The computer controls how long the injectors open. If the pressure is high enough to excessive amounts of fuel to fight thru an injector, the engine will flood and run like crap

[squonk 43,701]

Also if excessive fuel is being dumped into the engine, the computer will see this if the O2 sensor is working and cut back the fuel trim. Pretty much shut the injectors off. Again the car will run like crap. Get the O2 sensor checked!

[Lars 526]

This can be what your problem is lambda sensor is what we call it over the pond.. not sure what you guys call it...

i think that you call it the O2 sensor

Toyota Air Fuel Sensor / Oxygen Sensor P1135 Code not sure it that is the right code on your car

I think that should be the right code for an camary 2001 The obdII code p1135 which indicated a/f sensor(O2)

Your Toyota Camry oxygen sensor is a small unit with a cylindrical body; it's about the size of a spark plug. This heated sensor is equipped with three tail wires. On average, an oxygen sensor has a service life of about 50,000 miles,

Edited March 19, 2013 by Knusern

[wh500special 2,262]

Is the heat working adequately and is the engine coming up to temperature?

 

If a thermostat is bad and the engine isn't warming up, the car will use a lot of fuel trying to get it there. 

 

I'd guess you would have noticed a parking brake dragging or something by now...

 

Good luck,

Steve

[Kevbo 81]

Temperature is all good in the car. I am so impressed by you all! You have given me so much helpful information!! I will be scheduling an appointment with the dealer soon...what all should I tell them? I don't really want them to tack on unnecessary expenses...

[smoreau 658]

If you are going to take it to a shop for a better reading of the codes do it before cleaning the battery cables as bob mentioned was causing his problems above, because it will erase the error codes when you unhook the battery. Its not a big deal you just may have to drive it awhile for the error codes to reestablish themselves. I had a explorer once that a shop wanted to replace my transmission in because it was kicking in and out of overdrive and the codes showed a problem with the tranny, I replaced the battery cables and cured the problem. Talk about saving a dollar.

I have seen this before and changed a tranny that the customer wanted replaced without having me check it out first, Ended up needing a new TPS sensor after I replaced the trans as per his request, He know has me check out every thing first.

 

The ethanol in the gas, as well as oxygenation that is done in the winter months, will decrease mileage significantly. 

 

However, if the check engine light was on for awhile, I would take it somewhere other than Advance Auto Parts for a checkup. My independent auto service facility can analyze a code much deeper. There may be a bad ignition module or some other device that is causing the engine to not run efficiently. 

 

My Subaru was throwing intermittent codes saying that #1, 2, 3, & 4 cylinders were not firing correctly. Turned out to be a build-up of corrosion on top of the battery between the + terminal and the hold-down strap. How that caused misfiring is a mystery, but when I Googled it, I found that others were having the same problem.

 

Bottom line, take your car to a reputable shop to have the problem analyzed.    

 

I have seen this once! drove me nuts for 3 days

Everyone always says they put in the big dollar plugs. Expensive wires and a "high flow" air filter. Shouldn't that fix it? Well, it doesn't. As a few members said earlier, there are several pieces in this puzzle. I, myself would go for the fuel filter first. Reason being is. A plugged filter or even partially plugged, changes the fuel pressure to the regulator. So now the computer tells the other sensors, "I need more pressure". So in turn, they start  sending signals "more fuel" Which opens the regulator to flow more fuel but its not pressurized properly and the injectors dump it in a less vaporized manner which lessens burn which lessens the engines ability to be "efficient". Then, the O2 sensor sends a signal back to the computer saying "we have a lean burn situation here", so the computer tries to adjust again. It is a vicious circle.The O2 sensor or the MAF sensor or even a faulty temp sensor can wreak havoc on an EFI system. Strangely enough, even a bad or corroded plug on any one of the sensors could be giving a false reading. I don't go to a shop very often and do not own a diagnostic computer. I simply follow the general rules of an internal combustion engine. As my High School shop teacher always taught us, FFA - Fuel, Fire and Air, is all they need to run. Simple theory, but it works.

The basics are what you always start off with. Lots a very good information from 6wheeler!

 

Worked on Fuel injected cars for 20 years. Never seen a plugged or restricted filter cause an engine to burn more fuel. Fuel regulators usually are controlled by engine vacuum. The less vac the more pressure. The engine would have to be running pretty crappy for a pressure increase. The the computer will have to open the injectors longer to actually increase the amount of fuel going to the cylinders. I still say it a lazy O2 sensor telling the computer it's lean and adding fuel trim. You need a high dollar scanner to see this. 9 times out of 10 if the engine is pretty much running ok but has bad mileage it's O2 related.

I have seen a plugged fuel filters cause all sorts of issues on all makes of cars, Leading cause of convertor failure is a plugged fuel filter!!!! A plugged fuel filter WILL cause you to burn more fuel. Your fuel pressure will be fine, but the volume of fuel will be greatly decreased and cause the injectors  to  open farther and cause fuel trim to go richer counts. Also it will contaminate the O2 sensor will send the wrong signals to the PCM causing the car to run rich, but not set a SES light. You started out saying that you had a BOX STORE auto parts store scan your car for a code, They are NOT mechanics and it takes a trained mechanic with YEARS of experience to properly diagnose a this type of problem. By law, Advanced auto and any other auto parts store are NOT allowed to clear your codes. There have been many lawsuits for them doing this. They use this to sell parts, but do not have a clue what they are doing. With this said, you get what you pay for. If you want to know whats wrong with your car, take it to a trained mechanic that has the correct tools (scanner) to properly diagnose whats wrong. There are plenty of these shops around, but there twice as many shops that do not have the correct tools. Find one that specializes in Toyota and you should be fine.

 

Know back to your car. You said that the guy said it was not running efficient. That to me means that you may have had a code related to a catalytic convertor efficiency. This could be due to a plugged, or missing (hollow) convertor. bad O2 sensor, or dirty MAF. When we get a car in that is getting BAD fuel mileage, We start off by checking the basics.air,fuel filters and spark plugs. Replace as necessary, and do a scan to see what the computer is seeing, With out the code, I would say that is where I would start. If your convertor broke apart, a plugged fuel filter could cause it to run rich and not run bad.  Dirty MAF sensors can do all of the above also and aftermarket air filters that are cleanable use oil as part of the filtration and that can get on the sense wires of the MAF and cause all sorts of issues. There are just too many variables that it could be with out seeing the car in person. I would find a reputable auto repair shop that has the tools to work on a Toyota and go from there

[Kevbo 81]

Thanks so much smoreau! The one variable I can rule out would be the catalytic converter. I replaced mine last year with a brand new one. I do plan on going to the local Toyota dealer (Freedom Toyota) in Hamburg, PA.

[smoreau 658]

Sounds like a plan.

[Forest Road 594]

I had a 2001 Camry. Sold it to a guy at work years ago and he's still driving it. You do need to replace the timing belt at 7or so years and or 90,000 miles. There should be a sticker under the hood concerning the timing belt if it's been changed.It's not uncommon to see a few miles improvement in your mpg. But certainly not 16mpg! Hopefully it's soemethung simple. Best of luck.

[brybrychrismer 17]

We had A problem with my truck the ses light would come on for a while then go off. I went to one of the local parts stores they said it was the vacuum beaker on my gas cap. So bought a new one but was still having the same issue, so i ended up going to autozone having the codes read again this time came back as O2 sensor stuck in lean position. I replaced it and within 30 min of run time the ses went out and has yet to return. I would start by looking there. I have seen in some of the vehicles where the exaust has been changed that the back pressure on the exhaust has caused the ECM to throw all kinds of crazy codes. I just worked on an 06 mustang that the parts store said had a bad cam sensor but at the same time the battery was losing charge, of all things the alternator was going out. we replaced it and the codes cleared. The newer cars have so many electrical gizmos it can be almost anything. but i put money on the 02 sensor.      

[6wheeler 669]

If you are going to take it to a shop for a better reading of the codes do it before cleaning the battery cables as bob mentioned was causing his problems above, because it will erase the error codes when you unhook the battery. Its not a big deal you just may have to drive it awhile for the error codes to reestablish themselves. I had a explorer once that a shop wanted to replace my transmission in because it was kicking in and out of overdrive and the codes showed a problem with the tranny, I replaced the battery cables and cured the problem. Talk about saving a dollar.

I have seen this before and changed a tranny that the customer wanted replaced without having me check it out first, Ended up needing a new TPS sensor after I replaced the trans as per his request, He know has me check out every thing first.

 

>The ethanol in the gas, as well as oxygenation that is done in the winter months, will decrease mileage significantly. 

 

However, if the check engine light was on for awhile, I would take it somewhere other than Advance Auto Parts for a checkup. My independent auto service facility can analyze a code much deeper. There may be a bad ignition module or some other device that is causing the engine to not run efficiently. 

 

My Subaru was throwing intermittent codes saying that #1, 2, 3, & 4 cylinders were not firing correctly. Turned out to be a build-up of corrosion on top of the battery between the + terminal and the hold-down strap. How that caused misfiring is a mystery, but when I Googled it, I found that others were having the same problem.

 

Bottom line, take your car to a reputable shop to have the problem analyzed.    

 

I have seen this once! drove me nuts for 3 days

Everyone always says they put in the big dollar plugs. Expensive wires and a "high flow" air filter. Shouldn't that fix it? Well, it doesn't. As a few members said earlier, there are several pieces in this puzzle. I, myself would go for the fuel filter first. Reason being is. A plugged filter or even partially plugged, changes the fuel pressure to the regulator. So now the computer tells the other sensors, "I need more pressure". So in turn, they start  sending signals "more fuel" Which opens the regulator to flow more fuel but its not pressurized properly and the injectors dump it in a less vaporized manner which lessens burn which lessens the engines ability to be "efficient". Then, the O2 sensor sends a signal back to the computer saying "we have a lean burn situation here", so the computer tries to adjust again. It is a vicious circle.The O2 sensor or the MAF sensor or even a faulty temp sensor can wreak havoc on an EFI system. Strangely enough, even a bad or corroded plug on any one of the sensors could be giving a false reading. I don't go to a shop very often and do not own a diagnostic computer. I simply follow the general rules of an internal combustion engine. As my High School shop teacher always taught us, FFA - Fuel, Fire and Air, is all they need to run. Simple theory, but it works.

The basics are what you always start off with. Lots a very good information from 6wheeler!

 

Worked on Fuel injected cars for 20 years. Never seen a plugged or restricted filter cause an engine to burn more fuel. Fuel regulators usually are controlled by engine vacuum. The less vac the more pressure. The engine would have to be running pretty crappy for a pressure increase. The the computer will have to open the injectors longer to actually increase the amount of fuel going to the cylinders. I still say it a lazy O2 sensor telling the computer it's lean and adding fuel trim. You need a high dollar scanner to see this. 9 times out of 10 if the engine is pretty much running ok but has bad mileage it's O2 related.

I have seen a plugged fuel filters cause all sorts of issues on all makes of cars, Leading cause of convertor failure is a plugged fuel filter!!!! A plugged fuel filter WILL cause you to burn more fuel. Your fuel pressure will be fine, but the volume of fuel will be greatly decreased and cause the injectors  to  open farther and cause fuel trim to go richer counts. Also it will contaminate the O2 sensor will send the wrong signals to the PCM causing the car to run rich, but not set a SES light. You started out saying that you had a BOX STORE auto parts store scan your car for a code, They are NOT mechanics and it takes a trained mechanic with YEARS of experience to properly diagnose a this type of problem. By law, Advanced auto and any other auto parts store are NOT allowed to clear your codes. There have been many lawsuits for them doing this. They use this to sell parts, but do not have a clue what they are doing. With this said, you get what you pay for. If you want to know whats wrong with your car, take it to a trained mechanic that has the correct tools (scanner) to properly diagnose whats wrong. There are plenty of these shops around, but there twice as many shops that do not have the correct tools. Find one that specializes in Toyota and you should be fine.

 

Know back to your car. You said that the guy said it was not running efficient. That to me means that you may have had a code related to a catalytic convertor efficiency. This could be due to a plugged, or missing (hollow) convertor. bad O2 sensor, or dirty MAF. When we get a car in that is getting BAD fuel mileage, We start off by checking the basics.air,fuel filters and spark plugs. Replace as necessary, and do a scan to see what the computer is seeing, With out the code, I would say that is where I would start. If your convertor broke apart, a plugged fuel filter could cause it to run rich and not run bad.  Dirty MAF sensors can do all of the above also and aftermarket air filters that are cleanable use oil as part of the filtration and that can get on the sense wires of the MAF and cause all sorts of issues. There are just too many variables that it could be with out seeing the car in person. I would find a reputable auto repair shop that has the tools to work on a Toyota and go from there

 

Thanks Scott. I change fuel filters every time I tune up any of my vehicles. Even the big farm tractors get a new one every 250 hours. If a 245 hp diesel needs it, why wouldn't my cars and trucks. 

[bitten 134]

Reading your first post about the tune up you did, the first thing that came into my pee brain head was you didnt replace the gas filter. Not saying this is your problem but it should be part of a tune up. Codes can be confusing and in my experience the high doller code readers are the only way to go. I would have to say that Im lucky as I have a friend that has a very good Snap On that I can use. But even with the Snap On you still have to know how to look past what the scanner says as it might say the air inlet temp sensor is acting up and it could be the timing is out, or something else that the temp sensor is part of. 

With some knowledge, time and research you can figure it out. But sometimes it is best left to the pros.

Good Luck