Bad gas mileage !!!

Reply Subscribe

Thread Tools

Search this Thread

Aug 2, 2020 | 06:08 AM

F16uae

Thread Starter

Driver School Candidate

Joined: May 2020

Posts: 22

Likes: 2

From: Sharjah

Bad gas mileage !!!

So I had a fuel Consumption issue with my 01 430 and it used to average about 21-22 mpg on highway at 55 mph so to improve that I cleaned the maf using carburetor cleaner and the mpg instantly improved to about 27-28 mpg at 60-70 mph it was all perfect till a week and again in started to recieve just 21-23 mpg I cleaned the maf again It improved and back 21-23 mpg !!! Can anyone help me with this
and Yeah I Live in uae And I had searched Various Autoparts stores They dont have any kind of maf sensor cleaners . I got recommendation of using carb cleaner from one Auto maintenance workshop

Aug 2, 2020 | 09:43 AM

Bocatrip

Lead Lap

Joined: May 2006

Posts: 3,680

Likes: 302

Your fuel mileage seems to be fine...With regards to the MAF....I'm not a believer in cleaning it as it is quite delicate. In addition a new OEM Denso replacement is quite reasonable through Rock Auto....($50+). Good luck. FYI....My gas mileage doing 99% city driving is around 14-15 MPG which I think is satisfactory for an aircraft carrier. I don't use the car's computer to calculate the mileage. It can be off by as much a 1 mpg.

Aug 2, 2020 | 12:18 PM

YODAONE

Pole Position

Joined: Nov 2014

Posts: 3,254

Likes: 418

From: CALIFORNIA

Quote:

Originally Posted by F16uae

CRC brand Mass Airflow Sensor Cleaner is the right stuff. If auto parts store unwilling to order or otherwise not available locally, then should be available online.

Here's the thing...on my 1999 LS400, have cleaned MAF sensor with each air filter change.

Recently a MAF trouble code came up and cleaned it again.

The code dissipated, but after 178,000 miles, replaced the 21 year old MAF sensor with new purchased from Toyota/Lexus....$200

However, efficiency has improved appreciably, easily 20% with in city driving.

Not inexpensible, (possibly LS430 costs less), but payback over about 8,000 miles @ $3.00/gallon for premium and average 21 MPG

The rest of the engine is happier too...(catalytic converters, oxygen sensors, engine oil, valves (deposits), emissions, etc.)

Now seeing average 25 MPG. (Highway is 29 - 30 MPG despite LS400 has an LS430 engine transplant.)

Aug 2, 2020 | 01:31 PM

Striker223

Lexus Champion

Joined: Oct 2019

Posts: 17,926

Likes: 1,702

From: Ohio

Well you already found the problem, replace the sensor and perhaps your O2s as well while you are at it so that the main sensors are all new

Aug 2, 2020 | 10:20 PM

F16uae

Thread Starter

Driver School Candidate

Joined: May 2020

Posts: 22

Likes: 2

From: Sharjah

Quote:

Originally Posted by Striker223

Well you already found the problem, replace the sensor and perhaps your O2s as well while you are at it so that the main sensors are all new

when i scanned my obd i got codes for all o2 sensors (p0135 etc etc ) for the o2 heater circuit . Should i just replace the up stream o2 sensors as they control the fuel ratio ?

Aug 3, 2020 | 10:20 AM

bd3471

Driver School Candidate

Joined: Jan 2019

Posts: 26

Likes: 10

From: TX

Quote:

Originally Posted by F16uae

when i scanned my obd i got codes for all o2 sensors (p0135 etc etc ) for the o2 heater circuit . Should i just replace the up stream o2 sensors as they control the fuel ratio ?

I have an '04 and changed both of my upstream O2 sensors yesterday! Only the passenger side showed a code for the heater circuit and I confirmed there was an issue by watching the O2 switching on my techstream. Before I replaced the sensor I was getting 21MPG highway/18MPG combined. After replacing, I got 26MPG highway/23MPG combined!! Although I'm not sure if the ECU is still relearning. I noticed whenever I disconnect the battery, my MPG is higher as the computer relearns. City driving really seems to tank fuel economy. I highly recommend replacing the upstream with Denso from Rockauto ~$40 each. The downstream is considerably more and replacing is a pain bc you have to pull or cut front carpet as it plugs in next to shifter. What i did instead was buy Denso universal downstream sensors and spliced/rewired them to the old connectors

Aug 3, 2020 | 10:42 AM

F16uae

Thread Starter

Driver School Candidate

Joined: May 2020

Posts: 22

Likes: 2

From: Sharjah

Quote:

Originally Posted by bd3471

oh ! So thats why i see square cuts in my carpet near the console . Well i live in Uae and the New Parts are way Too expensive we have to buy it From Junkyard were the bring Japanese imported low mileage RHD cars