Thank you. My scan tool is kind of old and only runs on Windows with limited ability to graph. Which Bluetooth ODB device and app do you recommend?

 

It may sound strange but i have found that the cheaper economy gas stations have gas that may have more alcohol content or lacks the additives that quality gas has.I only use brand name fuel and get about 17.1 MPG.

 

Attached is the best I could do with my current software. I am getting P0171 and P1155 together and the engine idles rough as if it is going to shut down.
Does this provide any hints at what may be causing the rough idle and fuel efficeinecy of around 11 mpg?


The two codes at this time

 

I get around 20-21MPG in my 1999 RX 300. Used to be at 15mpg with previous owners, but since i've had the car i used 91 octane fuel and have also given the car several engine cleaners and switched to a full synthetic oil.

 

That's impressive if it's in city driving. I'm getting around 15mpg in city driving with regular gas. I didn't realize a combination of higher octane/engine cleaners/synthetic oil could boost it by 25%.

 

Well I don't do HEAVY city driving, I'd say light to medium amounts, cause where i live there isn't a whole lot of traffic. Mostly HWY driving. But I don't drive like a granny either. My best guess is that there was a lot of sludge in my engine.

 

rmk9785e,
Focus on P1155 first and ignore P0171 initially (general too lean code usually goes away after you fix P1155).

You should change your Bank 2 sensor 1, that is the one you have easy access from the front of the car. Its electrical (heater) circuit is gone. After that, clear all the codes, drive and see what code comes next, if any. This is your best plan of action. Search this forum and elsewhere, it is not a difficult DIY. There are excellent write-ups on how to fix P1155 (or change B2S1 A/F ratio sensor).

You can buy the Denso A/F ratio sensor (OEM) from Ebay, Amazon, or elsewhere. Don't buy a knockout, buy a Geniune OEM Denso 234-9009, in this case the OEM really does matter due to tight controls on these sensors. I am speaking from the personal experience. Make sure the Toyota or Denso name is on the packaging. Below are some examples, you may find even better deals if you search. (I have no connections to any of the three below, buy at your own risk/reward):

https://www.ebay.com/itm/OEM-AIR-FUE...-/253585820753
https://www.ebay.com/itm/234-9009-De...-/273289772811


[QUOTE=rmk9785e;10157749]Attached is the best I could do with my current software. I am getting P0171 and P1155 together and the engine idles rough as if it is going to shut down.
Does this provide any hints at what may be causing the rough idle and fuel efficeinecy of around 11 mpg?

 

I am still not able to figure out why my car consumes way too much fuel. On a full tank with 50-50 between city and highway, I am getting about 17.5l/100km. That's about 13.44 MPG. Let me add that my car is a 2002 awd European spec. And it has about 183,000 miles on the odo. Any help will be appreciated.

Simon

 

I am getting 15-16 mpg in city driving using regular gasoline with my 2000 RX300 AWD which is at 150,000 miles.

 

 

Your not putting that stuff in the oil I hope, it's supposed to go in your fuel

 

My 2003 RX300 with AWD gets about 18 in the summer in Scottsdale and 20 in the winter. I do notice a slight bump in fuel economy when using the high test from Costco. I do a mix of freeway and sidestreet driving. I drive it like I stole it. Gentle on the accelerator and brake pedal. Still runs strong for a car with only 207k miles on it.

 

I own an RX300 1999, 100k on the odo and have a problem with fuel consumption.
Orginal fuel consumption until recently was 6 km/l which dropped to 3.3 km/l.
Used Toyota diagnostic tool and it showed that one O2 sensor was bad.
Therefore, I changed all three O2 sensors and in addition cleaned all 6 injectors, found a small exhaust gas leak and this was attended too.
Reset the onboard computer. Then the reading starts from 6 km/l and drops again to 3.3 km/l.
Can anyone tell me what could possibly be wrong?

 

Is it still showing any code(s)?

 

I have the 2001 AWD model, and Either everyone else gas sucks or Im just lucky, I easily get the 19 miles per gallon city And even 20 on great no traffic conditions. And on good long out of town highway cruising days I sometimes see 26 mpg or more average. I will say this vehicle cannot compete with my previous 2014 kia optima that was seeing 32 or 34 highway all the time and 28 city, however this vehicle is built similar to a truck and gets similar mileage for some people. I can go through ditches and mud and rain and ice easily and I feel safe. And I cannot drive that way in my car. I deal with the trade off. I do hope you guys can see better fuel economy. I agree these vehicles can drink fuel. My vehicle sticker said 18 to 22, So I knew upfront and most of you guys should at least be getting that. These engines do have great gas mileage, however for the Rx was tuned for more power and the greater weight causes fuel mpg loss.