Hi gang, been a while. Been a few weeks that my milage has gone down. Getring about 420km on a full tank of gas. I was thinking winter tires on steelies and/or winter gas (here in Canada). It wasn't bad after i put winter tires on, so thinking maybe gas? This is the worst milage to date. Car is running well, no issues. Is tour milage the same? I think i need to sell this car.
fab

 

I'll let you know what my mileage was when I fill up my tank. I'm on my winters now (225/65), but with the stock alloy 17" rims. I've got a failing bank 2 cat and I usually go WOT on the highway at least once a day so that may reduce my MPGs a bit too. So far 200km on the tank and the needle is not close to half yet (Although it's a bit optimistic when the tank is more full I find).

I can get as bad as around 450 if my driving is strictly in the city.

 

wow.. i've gotten between 420-440km max in a full tank of premium fuel lately. It's nuts..between drives i notice the gas needle move quit a bit.
how do you know you have a bad cat? Do you have a CEL light on?

 

I also have to add that I only run 87 in my RX, but I never noticed a diff with premium. I have a CEL for it that can occasionally comes on, it also stinks sometimes like sulfur when I romp it. Other than that, no other lights or issues

 

2004 RX330 174k miles living in Boise so it's been high 20-40 F always running 87 octane still getting a bit over 20 mpg haven't been doing any highway driving lately summer I average 24-25 mpg.

Things I did that helped:
Cleaned throttle body
Sprayed both 02 sensors
Ran water through intake manifold to help with carbon
Reset ECM right after cleaning O2 sensors
Replaced aged cracking vent lines
Keep tires at 38-40 psi

Previously I replaced spark plugs, cleaned my fuel injectors, air filter replaced, alignment done

Note - I don't drive it hard

 

I did the same except cleaning 02 sensors and I keep my tires at 34-35 psi. I get very similar mileage to you. What did you use to clean the 02 sensors? I definitely want to when I replace my entire original exhaust and cats in the summer

 

Electrical contact cleaner to clean O2's, be sure to reset ECM you're starting fresh

 

Leeper...would using a can of "system cleaner", that you add to gas tank, work just as well for the o2 sensors? I know that my fuel trim reading were great just a couple of months ago.

 

Being the dull man that I am, I have recorded all my fuel expenses since purchasing the RX (second hand). First fill on 06 Nov, with the majority of driving in urban stop-start traffic

Located Australia, NSW

 

I do not believe so. I've used Seafoam on several vehicles but did not notice near as much difference as actually cleaning the O2 sensors with electrical contact cleaner and resting the ECM right afterwards. I just don't believe the miracle claims made by marketing companies especially regarding fuel injectors, removing carbon, MAF or O2 sensor cleaning I jsut don't think buring something in the combustion chanber or running a small amount of certain liquids can really do that much isolated improvement I more believe it is really great marketing

I did forget to mention I also sprayed my MAF at the same time so:

O2 sensor - using a 22mm or 24mm open end wrench I believe to remove the O2 sensor, I did not unplug it just turn it enough to allow it to come out, sprayed it with electrical cleaner or MAF cleaner (I believe it is likely the same stuff), once sprayed I "pre-turned" it a few times so that after reinstalling/screwing it back in the wires were straight again. My car is a non-salted road car they came out quite easily even after 171K miles. This procedure only took a few minutes for each of the two O2 sensors probably took longer to jack up the car than to clean the O2 sensors

MAF sensor cleaning - Open hood, MAF is right in front of you just remove the two screws, I sprayed it with MAF cleaner and reinstalled it. Careful to NOT touch the tiny element as that is extremely fragile just spray it. Super quick and easy

Throttle body - if you have not done this semi-recently it would be a good idea to do so. Quite easy you can use the same cleaner on a shop rag or brake cleaner or even Simple Green/Castrol cleaner just wipe down the inlet and butterfly valve it will have crud and gummy stuff on it. This requires removing the airbox so a little bit more involved

Reset ECM - just remove a battery cable for a couple minutes then I like to wipe down the post, apply a very thin film of grease to help with possible corrosion, reinstall termnal connectors

Reset windows, sunroof, rear hatch . Total time probably two hours for everything here

Your car will feel different in terms of shift points and throttle response for maybe 20-50 miles as it relearns your driving style. After doing these thngs I noticed a 20% improvement in MPG (significant). Anyone getting a "new to them" RX I'd highly recommend doing this or as a routine maintenance I'll do mine every 50K miles same with changing trans and diff fluids


Caution - do not touch O2 sensors when the engine is hot, you're messing with exhaust stuff it will burn you

These are not things the dealer or most mechanics will do even with a full tune-up but does make a big difference

 

Leeper....question...what was the best way to get to the rear o2 sensor? Did you have to jack up the car to get to it? I tried to unplug the front one, but couldn't get it unplugged.
also, when you went to reinstall them, did you add a bit of Anti-seize on the threading? Does it need the silver one of copper one?
thanks
fab

 

Upper is accessible from the top, lower I did from underneath yes I had to jack up the car. I did not unplug either one I was able to remove them, clean them, then reinstall without disconnecting them. As mentioned I did rotate them before reinstalling so that once they were tightened the wires were straight again. Mine came off fine so I did not feel anti-sieze was needed though I do have some here

 

I got 16.6 mpg or 14.2l per 100/km this tank (281 km, 40l used). This one was mostly city driving and I was romping on it and enjoying my newly installed limited slip rear diff.

 

I tried to get o2 sensor readings but my basic obd2 scanner doesn't seem to be reading the values.
concerning the o2 sensors, can someone tell me exactly where all 4 are located? Thanks
fab

 

Hi gang, so i was looking around under the hood to see if there was anything off. I noticed that there was a tube, that goes into the (back?) of the throttle body. It seems have started to slide out of the tube that hold it. It hadn't fully disconnected, but i think enough to have a gas/air leak out or suck into the Air intake. I put a clamp on it (circled in red). The line goes into an electric valve or sorts then a long tube (circled green), and goes behind the air box. Any idea what this tube is? Can it affect my milage (i know, maybe pulling at straws)?
Thanks
fab