lazersharp Posted October 2, 2011 Posted October 2, 2011 ONLY WHEN I WAS PICKING UP MY NEW 2012 RX 350 AWD A FEW DAYS AGO, THE SALESMAN TOLD ME THAT 2012 INGINE IS TUNED FOR REGULAR GAZ. IT WAS LIKE IF HE GAVE ME YET ANOTHER BONUS OF A COUPLE OF THOUSAND DOLLARS. (SAVINGS ON GAZ OVER A LIFE TIME OF THE CAR) WHAT A PLEASANT SURPRISE! I THINK IT WILL INCREASE SALES OF RX BIG TIME!
jaswood Posted October 2, 2011 Posted October 2, 2011 For about the last decade or more ALL EFI engines have been "tuned" for regular gas. Fuel a high compression engine that "requires(***)" premium fuel with regular and the ECU will automatic adjust, enrich, the A/F mixture under acceleration to abate even the slightest(***1) level of engine knock/ping. *** "requires" only for rated HP/Torque. ***1 New wideband non-resonant knock/ping sensors.
lazersharp Posted October 2, 2011 Author Posted October 2, 2011 I wonder, why only 2012 Lexus RX350 among all the other luxury brands came out with recommended regular gaz. As far as I am concern, it is a great selling tool enabling to sell more cars. I guess the others will follow now? Regular or premium, it's a great car. Smooth drive, muffler sounds sweet, comfortable, not mentioning the utility. I really like the tires it came with, Michelin Latitude HP 235/60/18 So far there is nothing I don't like about the car.
Ferns Posted October 6, 2011 Posted October 6, 2011 ONLY WHEN I WAS PICKING UP MY NEW 2012 RX 350 AWD A FEW DAYS AGO, THE SALESMAN TOLD ME THAT 2012 INGINE IS TUNED FOR REGULAR GAZ. IT WAS LIKE IF HE GAVE ME YET ANOTHER BONUS OF A COUPLE OF THOUSAND DOLLARS. (SAVINGS ON GAZ OVER A LIFE TIME OF THE CAR) WHAT A PLEASANT SURPRISE! I THINK IT WILL INCREASE SALES OF RX BIG TIME! I have a 2010 RX 350 and have been using regular gas all this time. Vehicle has no problems at all. Smooth ride as expected.
GDixon Posted October 7, 2011 Posted October 7, 2011 From what I have read, and IF the salesperson is correct, the engine would be "de-tuned" for regular gas. Earlier models de-tune themselves when regular gas is used by sensing engine knock. Jaswood explained this in post #2 of this thread. Believing a salesperson, whose job depends on moving cars off of the lot, may not be the best source of engine tuning facts. You thinking that it will increase the sales of the RX "big time" would be a motivating factor for a salesperson to put out this information to potential customers. Then the question arises, "Why did the salesperson wait until you picked up the RX to tell you this revelation?". Your manual should indicate the gas to use and/or a call to the service department may clarify the situation.
jaswood Posted October 7, 2011 Posted October 7, 2011 From what I have read, and IF the salesperson is correct, the engine would be "de-tuned" for regular gas. Earlier models de-tune themselves when regular gas is used by sensing engine knock. Jaswood explained this in post #2 of this thread. Believing a salesperson, whose job depends on moving cars off of the lot, may not be the best source of engine tuning facts. You thinking that it will increase the sales of the RX "big time" would be a motivating factor for a salesperson to put out this information to potential customers. Then the question arises, "Why did the salesperson wait until you picked up the RX to tell you this revelation?". Your manual should indicate the gas to use and/or a call to the service department may clarify the situation. "de-tuned" seems a little harsh. The engine/transaxle control ECU firmware will automatically adjust the fuel mixture according to the need. Due to the compression ratio one could say that the engine is "tuned"/DESIGNED for premium, which it undoubtedly is, but will self-adapt when/if regular is used. Use of regular will therefore adversely impact peak HP and FE. Since the A/F ratio only need be "adjusted", enriched, with high cylinder fills, or if lugging the engine (a rarity with automatics), the decline in FE will be negligible
GDixon Posted October 7, 2011 Posted October 7, 2011 From what I have read, and IF the salesperson is correct, the engine would be "de-tuned" for regular gas. Use of regular will therefore adversely impact peak HP and FE. Hmmmm....seems like the definition of "de-tuned". It may not be PC to state it that way but retarding the timing will influence the areas you mentioned. If the 2012 RX has the same HP rating and FE, along with the same engine designation, then my opinion is that the salesperson is misinformed. But maybe tweaking the ECU could produce what is claimed with out degrading performance. Without a declaration from Lexus corporate it is all conjecture.
jaswood Posted October 7, 2011 Posted October 7, 2011 From what I have read, and IF the salesperson is correct, the engine would be "de-tuned" for regular gas. Use of regular will therefore adversely impact peak HP and FE. Hmmmm....seems like the definition of "de-tuned". It may not be PC to state it that way but retarding the timing will influence the areas you mentioned. If the 2012 RX has the same HP rating and FE, along with the same engine designation, then my opinion is that the salesperson is misinformed. But maybe tweaking the ECU could produce what is claimed with out degrading performance. Without a declaration from Lexus corporate it is all conjecture. The way it was explained to me by a factory engineer is that the timing is not changed, with sub-standard fuel the A/F mixture is enriched when the engine is under heavy load, WOT, etc, to prevent/alleviate detonation.
GDixon Posted October 8, 2011 Posted October 8, 2011 Thanks for the clarification. Obviously you are better informed than am I.
lazersharp Posted October 9, 2011 Author Posted October 9, 2011 Whatever term you guys use, tuned or de-tuned makes no difference. The fact is that 2012 manual says: Recommended fuel - Regular
BCRCornet Posted October 12, 2011 Posted October 12, 2011 If the 2012 RX has the same HP rating and FE, along with the same engine designation, ... Note that the 2010 and 2011 RX 350 were rated at 275 HP. The 2012 RX 350 is rated at 270 HP.
lazersharp Posted October 12, 2011 Author Posted October 12, 2011 If the 2012 RX has the same HP rating and FE, along with the same engine designation, ... Note that the 2010 and 2011 RX 350 were rated at 275 HP. The 2012 RX 350 is rated at 270 HP I much prefer to pay 10¢ less for each liter of gaz (in Montreal) than have an extra 5 HP
jaswood Posted October 14, 2011 Posted October 14, 2011 If the 2012 RX has the same HP rating and FE, along with the same engine designation, ... Note that the 2010 and 2011 RX 350 were rated at 275 HP. The 2012 RX 350 is rated at 270 HP I much prefer to pay 10¢ less for each liter of gaz (in Montreal) than have an extra 5 HP On the other hand that extra 10 cents/liter may buy you more than 10 cents (15?) worth of additional gas mileage. Lexus didn't raise the bridge they lowerer the river. Simply enriched the mixture in order to run regular in a high compression engine without fear of detonation. If gas prices should go down substantially (fat chance) they'll go back to "Premium recommended".
SW03ES Posted October 15, 2011 Posted October 15, 2011 Yeah no changes have been made to these engines, they're simply adjusting the performance numbers so that they can market them as running on regular fuel. If gas prices go down (I don't see that happening) I agree they'll go back to recommending premium,
LexBob2 Posted October 16, 2011 Posted October 16, 2011 quote name='SW03ES' timestamp='1318690877' post='441826'] Yeah no changes have been made to these engines, they're simply adjusting the performance numbers so that they can market them as running on regular fuel. If gas prices go down (I don't see that happening) I agree they'll go back to recommending premium, There was a Q&A with a Toyota/Lexus engineer in the paper when the current gen ES350 came out, and was recommending premium fuel. He said premium was recommended "to achieve the advertised horsepower". At the time this was 272hp in the Lexus vs. 268-270hp in various Toyota applications.
lazersharp Posted October 16, 2011 Author Posted October 16, 2011 Can anybody see the difference between 168HP and 172HP? Does it really mean anything?
jaswood Posted October 16, 2011 Posted October 16, 2011 Can anybody see the difference between 168HP and 172HP? Does it really mean anything? Porsche says they are allowed plus or minus 10% on the final engine dyno test just prior to installation. 300 HP rating can mean 270-330 HP. So..no.
gosallygo Posted November 22, 2011 Posted November 22, 2011 Has anyone experienced problems using regular gas in a 2010 RX 350? I accidentally used filled the car up with regular (long day, don't ask) and am petrified that I have caused long-term damage. I know if I take the car in, someone will tell me I need some incredibly expensive replacement.
jaswood Posted November 22, 2011 Posted November 22, 2011 Has anyone experienced problems using regular gas in a 2010 RX 350? I accidentally used filled the car up with regular (long day, don't ask) and am petrified that I have caused long-term damage. I know if I take the car in, someone will tell me I need some incredibly expensive replacement. Since about 2000 the engine control ECU has had the ability to adjust the fuel mixture via EFI dutycycle to combat/alleviate problems resulting from low octane fuel in a high compression engine.
gosallygo Posted November 22, 2011 Posted November 22, 2011 Thanks! Crisis averted. Has anyone experienced problems using regular gas in a 2010 RX 350? I accidentally used filled the car up with regular (long day, don't ask) and am petrified that I have caused long-term damage. I know if I take the car in, someone will tell me I need some incredibly expensive replacement. Since about 2000 the engine control ECU has had the ability to adjust the fuel mixture via EFI dutycycle to combat/alleviate problems resulting from low octane fuel in a high compression engine.
BadBrad Posted November 27, 2011 Posted November 27, 2011 Has anyone experienced problems using regular gas in a 2010 RX 350? I accidentally used filled the car up with regular (long day, don't ask) and am petrified that I have caused long-term damage. I know if I take the car in, someone will tell me I need some incredibly expensive replacement. Have been using 87 octane in my 2010 for more than 2 years. No issues.
The G Man Posted December 6, 2011 Posted December 6, 2011 If there is no change to the engine in 2012, why havent Lexus change the octane requirement for all 3rd gen RX. It will lower the cost of ownership and make the CPO 3rd gen RX more marketable. My guess as to why is that there is a change in the 2012 engine rather it is a sofeware or hardware change, I am not sure. Also, 91 octane is require for the 2010 and 2011 RX, not recommanded. According to the owner's manual, it is ok to use 87 octane only when 91 is not available.
BadBrad Posted December 17, 2011 Posted December 17, 2011 The premium fuel "requirement," (the actual words are "required for best performance" and not "required or your warranty is void") is nothing but a marketing ploy to ensure the high priced Lexus makes something like 3.59 more horsepower than the lower priced Toyota pedestrian trash. If you are concerned that you car is slower in the quarter-mile for running 87 octane then lose 30 lbs. Run 87 all day, all year, and all decade. Your wallet will thank you.
skywagon Posted December 18, 2011 Posted December 18, 2011 Yeah no changes have been made to these engines, they're simply adjusting the performance numbers so that they can market them as running on regular fuel. If gas prices go down (I don't see that happening) I agree they'll go back to recommending premium, Purchase a couple of cans of Bushe's beans and you will have all the Gaz you need lol!
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