Fuel Economy Issues! Please help!
Thread Starter
Driver School Candidate
Joined: Jul 2012
Posts: 7
Likes: 0
From: Australia
Fuel Economy Issues! Please help!
Hi guys,
I am new to the forum and i live in Australia. I have a 2001 model GS300 and its getting extremely poor fuel economy. I am currently getting 338kilometers (210 miles) from a tank of petrol!
I have searched the site for solutions but i haven't had much luck. I tried cleaning the MAF sensor and running some injector cleaner but the fuel economy still has not improved.
The car currently has 120000km (74556 Miles) on the clock and there is no warning lights coming up on the dash.
Would it be wise to replace all 4 oxygen sensors and the MAF sensor?
Any help will be much appreciated!
Regards,
Nav
I am new to the forum and i live in Australia. I have a 2001 model GS300 and its getting extremely poor fuel economy. I am currently getting 338kilometers (210 miles) from a tank of petrol!
I have searched the site for solutions but i haven't had much luck. I tried cleaning the MAF sensor and running some injector cleaner but the fuel economy still has not improved.
The car currently has 120000km (74556 Miles) on the clock and there is no warning lights coming up on the dash.
Would it be wise to replace all 4 oxygen sensors and the MAF sensor?
Any help will be much appreciated!
Regards,
Nav
I recently changed my valve gasket and sparks plugs and noticed better gas. I fill up tomorrow so i'll keep track of the mileage. Lasts 10 days per tank daily driven but i'll reset the trip meter
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Pole Position
Joined: Jan 2012
Posts: 255
Likes: 0
From: Little Saigon, SoCaLi
Where did you get you Petro? From BP?
Just kidding mate, Did you used 91 Octane? Maybe your octane rating is different between Bristish and U.S overrated Octane rating. 
Stop and Go is not going to give you a 24 MPG. Around 14 mpg, if I am not missed -taken LOL.
Stop and Go is not going to give you a 24 MPG. Around 14 mpg, if I am not missed -taken LOL.
Instructor
Joined: Sep 2011
Posts: 1,242
Likes: 24
From: IL
I drive 70% highway, am easy on accel, and I am right now this tank at 340 miles and just a hair under 3/4 of a tank. It is pretty common I get 400 miles to a tank.
Look for fuel loss, leaks or evaporation.
Any check engine light?
Are plugs gapped right?
Does the engine run as smooth as glass or somewhat rough?
Is the alignment right? Look for odd tire wear.
I run 89 octane now and then, other than performance, mpg is unchanged.
Driving uphill all the time?
Is the Torque Converter locking?
Is the Trans getting into Overdrive?
Running it in pwr mode all the time?
Just ideas!
My best is just over 30 mpg with mine. So yes, you CAN get good mpg. Mine's a 98 GS400 with 166k miles (267000 km). I have good old fashioned NGK std plugs in (with 25k+ miles on them), I run a bottle of Chevron Techron thru every 6 months or so. I keep air pressure up to around 35 psi in front, 32 in rear. Nothing special at all.
I am NOT a fan of blindly replacing O2 sensors without some look at from the diagnostic port. If there are no codes, very likely you are simply wasting hard earned cash replacing them. Get a datalogger and monitor the O2 sensor swings, see if it is crossing over 0.45v several times a second. If they aren't leave them alone, if not, if they appear lazy, then consider it. And NEVER blindly replace in pairs. Look at it this way, statistically they will NOT fail in pairs!!! And nor do they need to be replaced in pairs. I have had O2's last 250k miles and still work perfectly.
And NEVER replace rear O2's without a cat convert efficiency code or other related code. Never. They are not primary fuel trim control. Leave them alone.
Look at a OBD2 interface based on this chip (http://www.obdsol.com/obd-interfaces/) not a ELM327. ELM's are lame. Trust me there.
Look for fuel loss, leaks or evaporation.
Any check engine light?
Are plugs gapped right?
Does the engine run as smooth as glass or somewhat rough?
Is the alignment right? Look for odd tire wear.
I run 89 octane now and then, other than performance, mpg is unchanged.
Driving uphill all the time?
Is the Torque Converter locking?
Is the Trans getting into Overdrive?
Running it in pwr mode all the time?
Just ideas!
My best is just over 30 mpg with mine. So yes, you CAN get good mpg. Mine's a 98 GS400 with 166k miles (267000 km). I have good old fashioned NGK std plugs in (with 25k+ miles on them), I run a bottle of Chevron Techron thru every 6 months or so. I keep air pressure up to around 35 psi in front, 32 in rear. Nothing special at all.
I am NOT a fan of blindly replacing O2 sensors without some look at from the diagnostic port. If there are no codes, very likely you are simply wasting hard earned cash replacing them. Get a datalogger and monitor the O2 sensor swings, see if it is crossing over 0.45v several times a second. If they aren't leave them alone, if not, if they appear lazy, then consider it. And NEVER blindly replace in pairs. Look at it this way, statistically they will NOT fail in pairs!!! And nor do they need to be replaced in pairs. I have had O2's last 250k miles and still work perfectly.
And NEVER replace rear O2's without a cat convert efficiency code or other related code. Never. They are not primary fuel trim control. Leave them alone.
Look at a OBD2 interface based on this chip (http://www.obdsol.com/obd-interfaces/) not a ELM327. ELM's are lame. Trust me there.
Last edited by RamAirRckt; Aug 24, 2012 at 09:12 PM.
Thread Starter
Driver School Candidate
Joined: Jul 2012
Posts: 7
Likes: 0
From: Australia
RamAirRckt thanks for the helpful information! I got my car scanned today and the mechanic said its coming up with faulty o2 sensor but he said he didn't know which one needed replacing.
I was unsure what you were trying to say here:
"And NEVER replace rear O2's without a cat convert efficiency code or other related code. Never. They are not primary fuel trim control. Leave them alone."
I think that means the sensors which are near or behind the cats don't need to be replaced?
How would i go about diagnosing which one it is? As far as i know there are 4 sensors which are:
Bank 1, Sensor 1
Bank 1, Sensor 2
Bank 2, Sensor 1
Bank 2, Sensor 2
https://www.clublexus.com/forums/att...components.pdf
Should i be replacing "Bank 1, Sensor 1 and Bank 1, Sensor 2"
If the ODB scanner is throwing an oxygen sensor code?
I'm sorry for my long posts! I'm not the most mechanically minded person
Regards,
Nav
I was unsure what you were trying to say here:
"And NEVER replace rear O2's without a cat convert efficiency code or other related code. Never. They are not primary fuel trim control. Leave them alone."
I think that means the sensors which are near or behind the cats don't need to be replaced?
How would i go about diagnosing which one it is? As far as i know there are 4 sensors which are:
Bank 1, Sensor 1
Bank 1, Sensor 2
Bank 2, Sensor 1
Bank 2, Sensor 2
https://www.clublexus.com/forums/att...components.pdf
Should i be replacing "Bank 1, Sensor 1 and Bank 1, Sensor 2"
If the ODB scanner is throwing an oxygen sensor code?
I'm sorry for my long posts! I'm not the most mechanically minded person
Regards,
Nav
Pole Position
Joined: Jan 2012
Posts: 255
Likes: 0
From: Little Saigon, SoCaLi
V8 gets better MPG than Inline 6
I drive 70% highway, am easy on accel, and I am right now this tank at 340 miles and just a hair under 3/4 of a tank. It is pretty common I get 400 miles to a tank.
Look for fuel loss, leaks or evaporation.
Any check engine light?
Are plugs gapped right?
Does the engine run as smooth as glass or somewhat rough?
Is the alignment right? Look for odd tire wear.
I run 89 octane now and then, other than performance, mpg is unchanged.
Driving uphill all the time?
Is the Torque Converter locking?
Is the Trans getting into Overdrive?
Running it in pwr mode all the time?
Just ideas!
My best is just over 30 mpg with mine. So yes, you CAN get good mpg. Mine's a 98 GS400 with 166k miles (267000 km). I have good old fashioned NGK std plugs in (with 25k+ miles on them), I run a bottle of Chevron Techron thru every 6 months or so. I keep air pressure up to around 35 psi in front, 32 in rear. Nothing special at all.
I am NOT a fan of blindly replacing O2 sensors without some look at from the diagnostic port. If there are no codes, very likely you are simply wasting hard earned cash replacing them. Get a datalogger and monitor the O2 sensor swings, see if it is crossing over 0.45v several times a second. If they aren't leave them alone, if not, if they appear lazy, then consider it. And NEVER blindly replace in pairs. Look at it this way, statistically they will NOT fail in pairs!!! And nor do they need to be replaced in pairs. I have had O2's last 250k miles and still work perfectly.
And NEVER replace rear O2's without a cat convert efficiency code or other related code. Never. They are not primary fuel trim control. Leave them alone.
Look at a OBD2 interface based on this chip (http://www.obdsol.com/obd-interfaces/) not a ELM327. ELM's are lame. Trust me there.
Look for fuel loss, leaks or evaporation.
Any check engine light?
Are plugs gapped right?
Does the engine run as smooth as glass or somewhat rough?
Is the alignment right? Look for odd tire wear.
I run 89 octane now and then, other than performance, mpg is unchanged.
Driving uphill all the time?
Is the Torque Converter locking?
Is the Trans getting into Overdrive?
Running it in pwr mode all the time?
Just ideas!
My best is just over 30 mpg with mine. So yes, you CAN get good mpg. Mine's a 98 GS400 with 166k miles (267000 km). I have good old fashioned NGK std plugs in (with 25k+ miles on them), I run a bottle of Chevron Techron thru every 6 months or so. I keep air pressure up to around 35 psi in front, 32 in rear. Nothing special at all.
I am NOT a fan of blindly replacing O2 sensors without some look at from the diagnostic port. If there are no codes, very likely you are simply wasting hard earned cash replacing them. Get a datalogger and monitor the O2 sensor swings, see if it is crossing over 0.45v several times a second. If they aren't leave them alone, if not, if they appear lazy, then consider it. And NEVER blindly replace in pairs. Look at it this way, statistically they will NOT fail in pairs!!! And nor do they need to be replaced in pairs. I have had O2's last 250k miles and still work perfectly.
And NEVER replace rear O2's without a cat convert efficiency code or other related code. Never. They are not primary fuel trim control. Leave them alone.
Look at a OBD2 interface based on this chip (http://www.obdsol.com/obd-interfaces/) not a ELM327. ELM's are lame. Trust me there.
him
I get around 315-330 miles on a full tank, combined Highway/City. And that is after all the major tuned up. Before 240 miles.
Last edited by GS714; Aug 25, 2012 at 08:59 AM.
Just hit 101.8 miles with 3/4 tank of gas left. 4days on a quarter tank... 1 day freeway the rest city
Instructor
Joined: Sep 2011
Posts: 1,242
Likes: 24
From: IL