ssgi4in12

I recently bought a 2002 Rx 300 European model with 46,000km. But the car computer shows around 26l/100km. I do mostly city driving with heavy traffic lasting for 30mins sometimes. The least I saw as average on the car computer was 24l/100km. I need help on how to reduce my fuel consumption

salimshah

Welcome to Club Lexus.

Have you looked at the sticky thread "I have bad gas milage..."

Salim

6.0PSD

Welcome to my world of bad fuel economy... That sticky salimshah pointed out does have a lot of good info... Take your time and read it through carefully as it may contain what you need to help you figure out what is going on with yours, not every vehicle has same issue but it will be great info to help you diagnose your current or future fuel economy issues...

​​​​If I did the math correctly then you are getting about 9 miles to the gallon... That was me about 2,000 miles ago... I have been just adding cans/bottles of all types and brands of expensive fuel additives to the tank for just about a year and have slowly made my way up to about 12 miles to gallon... I don't drive the rx much so I just kept adding those "mechanics" in a can to it and have yet to get the fuel economy under control... I am currently diagnosing it with a scanner to hopefully get to the bottom of it... Mine is now more than likely pointing at an A/F (O2) sensor at bank 1 sensor 1 and I just recently ordered one to see if it will finally fix it... The only code I have been getting was P0171 and just recently got it again so I did not clear it this time to see if any other codes pop up in the next few weeks.

Is your check engine light on? If so, do you have a way to read the codes?

​​​If you are getting any codes then it is best to post them here to better help you...

ssgi4in12

Thanks to you guys for your response. Initially I got three codes p0505, p0174, P0420. Then I had a leaking exhaust and rough idle. I managed to fix the leaking exhaust and cleaned the IACV and cleared the codes. After about 120km the only code that returned was the p0174. New info is that I did a 70km journey on the high way and the average number is reducing to 18l/100km.

JAB

Where is the 'Abia State?' You're likely to get more meaningful feedback from this forum if you convert your data to miles per gallon.

ssgi4in12

Additional info. I did a 52km trip after refuelling and the computer showed 12.3l/100km that's about 19mpg after driving upward of 80km/h. I had to scan the system again with autel obd scanner and saw code P0420 that had something to do with the catalyst converter bank 1. How do I solve this problem and increase my mpg. Meanwhile, I live in Nigeria.

ssgi4in12

Here is a picture of the scan tool freeze frame data of the car. Can someone help me understand it pls.

ssgi4in12

Thanks Salim..
In trying to identify what the culprit is really, I had to purchase a new scan tool for better understanding.

I had to read the voltage of the oxygen sensor bank 1 sensor 2 and the two af sensors. The voltage if the two af sensors are mostly similar. But when I press the throttle, it is always around 3.1 and 3.2 and when I decelerate, they went up to 4. 1 some time. The 02 sensor bank 1 sensor 2, is usually at 0.1v at idle and can climb up to 0.9v when I match th the throttle.

Does these readings point to a bad cat or what other tests should I run to identify the actual culprit?

I did a mod 6 test and I am attaching the pictures too. I had the P0420 cleared this morning and it came back after about 15km drive.







​​
​

salimshah

Sorry bud, I am not an expert in interpreting the real time values from the scanner.

Maybe some other member can guide you better.

I can offer help at basic level ..

free roll/drag ... brakes hanging, bearings binding etc.
Getting into over drive ... engine rpms at say 65mph (please convert for me)
Operating temo ... temp gauge near 1/2
Air filter
Plugs [oem-pregapped]
idle rpm in drive with foot on the brake
Smoke color
tire condition/alignement

Salim