lexus114

I had a strange thing happen to my rx today,not too long ago I tried a little experament with regular fuel.Some of you may have read the results i came up with.Anyway,since returning to the premium fuel,it was a whole lot better,but somehow still not quite like it was before.Today it felt like it was really (what i like to call,holding back power).Now,i remember reading somewhere on another site,that when the computer retards the timing for regular fuel,you have to actually clear the computer,when you go back to the premium.The computer will eventually re-set it,but how long does it take?So,I went in with my hand held scanner to see if their was any pending codes(no cel)Their was no pending,or hard codes.While i was in their,I cleared(reset)the computer.went out for a drive,Presto! runs great again.:> could really feel the variable valve timing kick in,and no more holding back feeling.Now,what exactly caused this,not totally certain.Only thing i can think of is,after i used the regular fuel,it may not have advanced the timing all the way back to where it belonged.When you reset the comp.it goes off the pre-programed prom,for its information.just a little something to ponder out their.

Lexmex

Will take note of this on the weekend, as I will move back to Premium down here after a week's experiment on regular.

TampRX300

why are you going back to premium? Found bad results? I filled up with regular when I purchased the RX just because, whatever... well, on the way home it felt weird and as some of you might know, the CEL was missing so I didn't know of a code until I went in and replaced the light. I got P1135 and P0125. Well, last night I filled up with premium and the weirdest thing happened today. The CEL light turned off for about 30 miles of driving or so and the RX felt really smooth for that time. Now the light came back on, with the same codes plus and it's semi-stalling and sputtering too much. I wonder if the fueling change had anything to do. I'm waiting to do the a/f sensor to re-set the thing and start using premium once and for all. Good notes..

bob2200

I'd guess that you have a borderline problem that should be solved before it gets worse. I have used regular gasoline (87 octane) in my RX300 100% since new and I think it runs just fine. I've had two O2 sensors burn out in 60,000 miles, but I don't that's particularly unusual.

lexus114

In response to Tamprx300,yes i found that my RX was not herself on regular unleaded.As i had previously mentioned before (joking of course) it felt like driving a Grand Torino with a 200 cid 6 cylnder under the hood.As you may know,not quite that bad,but was not as strong pulling hills, Freeway entering, mid range power,etc.And down where you are,in Florida,i would definately use premium fuel.Of course i consider myself some what of a performance driver,and that makes a difference too.If you drive like an old pappy,you may never notice the difference.(just havin a little fun here :>)

19psi

yes, the computer takes a while to give full timing back after it sees a pre ignition event for engine safety.
read this: https://www.clublexus.com/forums/sho...d.php?t=334846

Lexmex

Regular gas has other issues down here beside lower octane: high sulphur and I contend it is quite dirty.

TampRX300

Speaking of performance, I'm really used to high end power like 600+ RWHP and over 700 FtLbs of torque (can't beat nitrous on torque), so either way the RX feels like a shopping cart to me in that sense, BUT, I do feel the difference with the change of fuel grade. I guess the VVT has a huge impact on it, or vice-versa. I also noticed the with the fill up of 87, I only got 260 miles out of the tank as opposed to 287 with 93. Might be worth the extra pennies, but remember I'm driving with a bad A/F sensor right now...

lexus114

You just have a bad heater element in the sensor,right?

lexus114

Lex,how much of a difference did you notice on regular?And sulphur is what makes the fuel burn in the first place,right? Here in the northeast,Our fuel is a low sulphur formula(not very good oxygenated crap)u.s fuel might be cleaner,but still not what it should be, due to emissions restrictions.

mikey00

That was an excellent explanation of 87 vs. 93 in the link provided. Just remember, that when you are on that link and reading about the benefits, they are discussing the LS, which requires premium not the RX. I have used nothing but 87 in my 2000 RX and now for 125K in my 2001 RX, other than for a few experiments with premium. If the car went any faster with premium it was only because my wallet was lighter.
I just pulled the plugs at 125K yesterday and they are in excellent condition. I have also never had a valid CEL. Regular vs. premium has been discussed many times in the past here. Even a survey was done. You can get this with search if you are interested.

lexus114

Treuly,i know this is off topic,but i dont run regular unleaded in anything.Even my cub cadet lawn tractor,runs smoother,and starts up better on 89 octane.To me,regular is the cheapest gasoline a motor can function on,and that is about all.Just enough octane to run on.I`m not trying to start beating a dead horse again,but over the years,this is what i have personaly observed.Just my opinion :>,thats all 10-4?

TampRX300

I believe so, code P1135.

lexus114

Well,i guess its not as urgent then.But i would still replace,and reccomend doing both a/f sensors go to www.OxygenSensors.com