I have a bad gas mileage, how about yours ??

[rx300s415]

Ok, I just took out the MAF sensor today and realized...there wasn't even a red diode. It was so dirty it just looked black (on one whole entire side). I ran over to the local auto part store and grabbed a can of "MAF Sensor Cleaner," it's some solvent-looking spray made from CRC. I came home and gave both sides about 10-15 sprays of the cleaner. Forgot to spray the two thread-looking things that you seen when you turn the sensor upside down. I've been getting 13mpg in the city, so hopefully I'll start seeing improvements. Thanks Lex for the list of things to check!

BTW, I'm running a K&N air filter....maybe that's why the sensor was all dirty and oily.

[toy4two]

sticky this, very important.

[Lexmex]

Originally Posted by toy4two

sticky this, very important.

I'll stick it as I suppose that over time we will add other ideas.

[bowen.chau]

Thank you very much for the help.

I will take my Harrier to the garage these two days for the cleansing, and will let you guys know the result.

[bowen.chau]

After cleaning all the things mentioned, my gas mileage is still very bad, like 4.6km / L.

So, today my garage hooked the diagonise computer and discovered one of the three O2 sensor has 0 Volt, which means .... dead....

So, planning to get it changed next week.

I think O2 sensor affect the gas mileage, right?

[Lexmex]

Originally Posted by bowen.chau

After cleaning all the things mentioned, my gas mileage is still very bad, like 4.6km / L.

So, today my garage hooked the diagonise computer and discovered one of the three O2 sensor has 0 Volt, which means .... dead....

So, planning to get it changed next week.

I think O2 sensor affect the gas mileage, right?

It sure does affect gas mileage. We get a lot of blown sensors on vehicles down here, most people don't know until emissions time or when they realize they are wasting too much gas. A Renault Clio my company owns kept not being driven because people claimed it was wasting too much gas. My uncle serviced it and realized it had a bad A/F sensor and then one week later a bad ignition coil.

[Meetya]

Originally Posted by bowen.chau

After cleaning all the things mentioned, my gas mileage is still very bad, like 4.6km / L.

So, today my garage hooked the diagonise computer and discovered one of the three O2 sensor has 0 Volt, which means .... dead....

So, planning to get it changed next week.

I think O2 sensor affect the gas mileage, right?

4.6km/L is 11 MPG. Normal is 17 MPG.
Does your car jerk at high speeds but low RPMs?

Check out these two threads:
http://www.clublexus.com/forums/rx-first-generation/288374-freaking-p0125.html
http://www.clublexus.com/forums/rx-first-generation/295986-jerking-like-no-gas-around-55mph.html

[bowen.chau]

What does it mean by "jerk at high speed"?

My car always keep low RPM in highway ... Gear 3 always below 2000 rpm on street roads.

[bowen.chau]

Oh yeah !~
My RX300 is now wasting too much gas right now...

[bowen.chau]

Just read the articles ...

No, my car doesn't jerk at high speed.

[bowen.chau]

I have just sent the car to the garage again this afternoon the O2 sensor replacement. Let's see if the gas mileage can be improved after the service.

[bowen.chau]

The O2 sensor hasn't been changed yesterday since my garage man cannot take out the sensor behind the Cat. However, there is a sign that the car has black exhaust ... Is it a sign for incomplete fuel burn ??

[Lexmex]

Originally Posted by bowen.chau

The O2 sensor hasn't been changed yesterday since my garage man cannot take out the sensor behind the Cat. However, there is a sign that the car has black exhaust ... Is it a sign for incomplete fuel burn ??

Where are you seeing the black exhaust?

In addition, which cat are you referring to, there should be two precats off of the manifold and 1 cat underneath the vehicle. The O2 sensor after the main cat underneath the vehicle isn't the key for the gas mileage, that would be the two A/F sensors before the precats.

[bowen.chau]

Okay, finally my car has entered Toyota's (Lexus) garage today and the technician told me that the air mass is doubled more than normal. The reading on my car right now is 5.x and the norm is 2.x. That's why my car is now sucking fuel. He suggested me to change the MAF (which is next the air box) first to see if anything can be improved. He also told me that two O2 sensors in front (not the one behind the cat underneath the vehicle) have "Freezed" since the reading from MAF has exceeded the O2 sensors' handling ability. He hopes that after changing the MAF can make those two O2 sensors work again.

One more question, does your fusebox feel hot after a 40 min ride?
Many thanks.

[bowen.chau]

One more thing, my garage man has swapped his MAF sensor from his Echo to mine. Still no changes. Is the MAF sensor on Echo different from mine? They look really the same.