Low Mpg On Old 2001 Rx300

[Miracle]

I bought this used 2001 RX300 (AWD) last month. Current mile age 95,300. I noticed that the fuel economy of this car is getting worse.

According to http://www.fueleconomy.gov/!Removed!/noframes/16904.shtml, this car should be at 16 - 21MPG depends on city/hwy type, combined around 18. But mine is running at 13.5MPG now (city/hwy is about 50/50). When I bought it the info panel displayed 14.4 average MPG, now it seems to be doing worse.

I did the 90,000 mile service at the dealer on Xmas day. Did not see any improvement. I calculated the MPG value manually for the most recent 200 miles. The result matches the average MPG value on the car display panel.

Is there anything I can do (e.g. clean up some part of the fuel system / engine) to get better MPG value? Does Chevron Techron fuel system cleaner help?

Thank you!

[code58]

The dealer was open Christmas day? Shame on them, everyone should have Christmas day off. At 90k mi. I doubt that the plugs need changing, they are not like regular plugs, they are Iridium and are probably not worn at all at 90k. You might research "cleaning the MAF sensor". It needs to be done if it hasn't ever been done, but needs to be done with a full understanding of how it is done- it's very fragile! Chevron Techron is one of the best cleaners you can buy and it can't hurt to use it, but it may or may not help the mileage. MAF cleaning comes 1st. and anything else after that. Let us know if it makes any difference. Winter driving is hard on mileage.

[carguy07]

Is you check engine light on/working?

[Miracle]

Is you check engine light on/working?

It was on, the dealer charged me $1,000 to fix it (replaced CC/VSV)....

[Miracle]

The dealer was open Christmas day? Shame on them, everyone should have Christmas day off. At 90k mi. I doubt that the plugs need changing, they are not like regular plugs, they are Iridium and are probably not worn at all at 90k. You might research "cleaning the MAF sensor". It needs to be done if it hasn't ever been done, but needs to be done with a full understanding of how it is done- it's very fragile! Chevron Techron is one of the best cleaners you can buy and it can't hurt to use it, but it may or may not help the mileage. MAF cleaning comes 1st. and anything else after that. Let us know if it makes any difference. Winter driving is hard on mileage.

Do you mean spark plugs? I'm a car noob.

If I need to replace the plugs (very unlikely), and clean the MAF sensor, any idea how much will it take? I don't want to go to the dealer any more.

Thank you!

[lexus114]

The dealer was open Christmas day? Shame on them, everyone should have Christmas day off. At 90k mi. I doubt that the plugs need changing, they are not like regular plugs, they are Iridium and are probably not worn at all at 90k. You might research "cleaning the MAF sensor". It needs to be done if it hasn't ever been done, but needs to be done with a full understanding of how it is done- it's very fragile! Chevron Techron is one of the best cleaners you can buy and it can't hurt to use it, but it may or may not help the mileage. MAF cleaning comes 1st. and anything else after that. Let us know if it makes any difference. Winter driving is hard on mileage.

Do you mean spark plugs? I'm a car noob.

If I need to replace the plugs (very unlikely), and clean the MAF sensor, any idea how much will it take? I don't want to go to the dealer any more.

Thank you!

What grade fuel are you using?

[code58]

The dealer was open Christmas day? Shame on them, everyone should have Christmas day off. At 90k mi. I doubt that the plugs need changing, they are not like regular plugs, they are Iridium and are probably not worn at all at 90k. You might research "cleaning the MAF sensor". It needs to be done if it hasn't ever been done, but needs to be done with a full understanding of how it is done- it's very fragile! Chevron Techron is one of the best cleaners you can buy and it can't hurt to use it, but it may or may not help the mileage. MAF cleaning comes 1st. and anything else after that. Let us know if it makes any difference. Winter driving is hard on mileage.

Do you mean spark plugs? I'm a car noob.

If I need to replace the plugs (very unlikely), and clean the MAF sensor, any idea how much will it take? I don't want to go to the dealer any more.

Thank you!

Yes, Mr. M- That would be spark plugs. They put some of the finest plugs known to man in these cars. Even my wife's '02 Camry 4cyl came with them. Cost them a few $'s apiece for Toyota rather than a few cents apiece like our American manufacturers. They list for around $19. each and can be purchased online for about $8. ea. Don't confuse them with the Platinum Denso's that Autozone sells for about $8. ea. You might consider taking the plugs out and checking them, fine wire brushing them and maybe a little bit of carb cleaner, but only because that's an all aluminum engine and when I changed My DIL's at 97k (not knowing), one of the rear plugs came a little hard because it had 97k mi of crud on the threads (yes, it's possible for carbon to get up on the threads over a long period of time), and I was afraid I might gall the threads and really be in trouble. Didn't happen, and I put a very small amount of anti-seize on the threads when the new plugs went in.

As far as the MAF sensor, there are GOOD instructions on cleaning it on this forum and ANOTHER popular Lexus forum. It's not hard to do, you just need to know what to use and how to be careful in the cleaning so that you don't damage the delicate sensor parts as you are cleaning. I would rather you read those instructions rather than me repeating them so that there is no misundertanding. You should have no trouble doing it. Make sure to get and use the right cleaner. It's still the 1st. thing I would do.

[Miracle]

The dealer was open Christmas day? Shame on them, everyone should have Christmas day off. At 90k mi. I doubt that the plugs need changing, they are not like regular plugs, they are Iridium and are probably not worn at all at 90k. You might research "cleaning the MAF sensor". It needs to be done if it hasn't ever been done, but needs to be done with a full understanding of how it is done- it's very fragile! Chevron Techron is one of the best cleaners you can buy and it can't hurt to use it, but it may or may not help the mileage. MAF cleaning comes 1st. and anything else after that. Let us know if it makes any difference. Winter driving is hard on mileage.

Do you mean spark plugs? I'm a car noob.

If I need to replace the plugs (very unlikely), and clean the MAF sensor, any idea how much will it take? I don't want to go to the dealer any more.

Thank you!

What grade fuel are you using?

Plus or premium, depends on the price. Usually premium. But I know the previous owner used only regular.

[Miracle]

The dealer was open Christmas day? Shame on them, everyone should have Christmas day off. At 90k mi. I doubt that the plugs need changing, they are not like regular plugs, they are Iridium and are probably not worn at all at 90k. You might research "cleaning the MAF sensor". It needs to be done if it hasn't ever been done, but needs to be done with a full understanding of how it is done- it's very fragile! Chevron Techron is one of the best cleaners you can buy and it can't hurt to use it, but it may or may not help the mileage. MAF cleaning comes 1st. and anything else after that. Let us know if it makes any difference. Winter driving is hard on mileage.

Do you mean spark plugs? I'm a car noob.

If I need to replace the plugs (very unlikely), and clean the MAF sensor, any idea how much will it take? I don't want to go to the dealer any more.

Thank you!

Yes, Mr. M- That would be spark plugs. They put some of the finest plugs known to man in these cars. Even my wife's '02 Camry 4cyl came with them. Cost them a few $'s apiece for Toyota rather than a few cents apiece like our American manufacturers. They list for around $19. each and can be purchased online for about $8. ea. Don't confuse them with the Platinum Denso's that Autozone sells for about $8. ea. You might consider taking the plugs out and checking them, fine wire brushing them and maybe a little bit of carb cleaner, but only because that's an all aluminum engine and when I changed My DIL's at 97k (not knowing), one of the rear plugs came a little hard because it had 97k mi of crud on the threads (yes, it's possible for carbon to get up on the threads over a long period of time), and I was afraid I might gall the threads and really be in trouble. Didn't happen, and I put a very small amount of anti-seize on the threads when the new plugs went in.

As far as the MAF sensor, there are GOOD instructions on cleaning it on this forum and ANOTHER popular Lexus forum. It's not hard to do, you just need to know what to use and how to be careful in the cleaning so that you don't damage the delicate sensor parts as you are cleaning. I would rather you read those instructions rather than me repeating them so that there is no misundertanding. You should have no trouble doing it. Make sure to get and use the right cleaner. It's still the 1st. thing I would do.

Thanks for the detailed answer. Today I took the MAF sensor out and took a close look. The air temp sensor is easy to inspect & clean, it was covered with oiled dust, I managed to clean up most of them=;, but the inner stuff is really hard to see clearly, even with a flashlight. I went to the auto parts shop and tried to find some MAF sensor cleaner but wasn't able to. They have fast dry air intake cleaner and carbon cleaner. Can I use the air intake cleaner?

[carguy07]

Delete

[code58]

I imagine the air intake cleaner would be O.K. or electronics cleaner.

I did a little more research and I found what I thought was available. It is called "Mass Air Flow Sensor Cleaner". It is by CRC which you should be able to find anywhere, it is probably the most popular cleaner in many cleaners of different specialty kinds. Virtually any auto parts store should carry it. It's about $4. a can. You just want to spray into where the delicate sensor parts are, but not too hard, let the cleaner do the job. Those parts are very delicate. Good luck.

[lexus114]

I imagine the air intake cleaner would be O.K. or electronics cleaner.

I did a little more research and I found what I thought was available. It is called "Mass Air Flow Sensor Cleaner". It is by CRC which you should be able to find anywhere, it is probably the most popular cleaner in many cleaners of different specialty kinds. Virtually any auto parts store should carry it. It's about $4. a can. You just want to spray into where the delicate sensor parts are, but not too hard, let the cleaner do the job. Those parts are very delicate. Good luck.

re setting the ecm after cleaning might be a good idea as well.

[Miracle]

Thank you. I think I'll go to another auto parts shop to see if I can find the CRC MAF sensor cleaner.

[Miracle]

OK, a few weeks ago I cleaned up the MAF sensor with CRC electronic cleaner, the gas mileage went up to 15.5 but now it is back to somewhere around 13.5. Recently I was not driving much on highway, but I guess it should not go as low as 13.x.

Also when the engine is started in the morning (cold), the offgas from the exhaust has an obvious smell of gasoline. It goes aways when the car completely warms up. Is this normal?

Any idea what I should/can do now?

[Paticake]

Hey Miracle, I have a 2002 RX300, 107K miles, and my gas mileage has dropped down to 13+, also these past few months. Since last May my commute has change to less than 5 miles, but I noticed the mileage change around late Nov/early Dec.

I was going to try working on the MAF sensor after reading your situation, looks simple enough, but the weathers been working against me.

I'm due for oil change, thought I might ask them to check it.

Keep posting so I know how you make out.