g4driver

FIRST... In Europe and Australia, an octane rating (such as 96 in Germany) is a direct measurement of the Research Octane Number (or RON) which is measured by running the fuel through a specific engine under very specific test conditions. In the US, Canada and a few other countries, the octane rating on the pump IS NOT the RON. It is derived by summing the RON and the Motor Octane Number then dividing the result by two. The Motor Octane Number is a completely different (and more stringent test) that simulates running the fuel through an engine in more stressful conditions. As a result, the Motor Octane Number is usually 8-10 points LESS than RON for the exact same fuel. Since the octane rating displayed on North American pumps is one half of the sum of the two ratings, the same fuel will have an octane rating displayed of 4-5 points less than what would be displayed in Europe and Australia for the same fuel. So if that German fuel with a 96 RON were brought to the US or Canada, it would be advertised as 91 or 92 octane fuel. I put 93 Octane fuel in my LS-430 and this would be advertised as 97 or 98 Octane in Europe. SECOND... Octane has no direct effect on the deflagration (burning characteristics) of a fuel. In other words, higher octane fuel does not burn faster than lower octane fuel. It's sole effect is on detonation effect and that's because higher octane equates to a higher activation energy - the energy necessary to begin the chemical reaction we know as either combustion or detonation. Since a higher octane has a higher activation energy, it is more resistant to detonation. THIRD... Octane has no effect on the energy per unit volume of a fuel. All other things being equal, one liter of 89 Octane has the same inherent stored energy as one liter of 93 Octane. HOWEVER, most fuel manufacturers formulate the fuel that will go into making a higher Octane fuel with more energy per liter - creating a more powerful and quicker burning fuel. FOURTH... In Russia, the standard octane is 80 RON. Now how'd you like to run your Lexus on that crap??? !!! Cheers

I second the recommendation for a fuel system 'flush'. Similar Codes on my wife's car and the dealer wanted $1200 to replace 2 air sensors and the air meter. They did what sounds like a motorvac on it (flush the system and clean the throttle body) and the engine seems to run well. The light is out now and when I took it to a different mechanic for a second opinion, he actually hooked up a voltage sensor to the different sensors and they were operating normally. The other thing I've instructed my wife to do is run 93 Octane in the engine and see if the pinging that originally signalled a problem is evident. If not, we're gonna step down to 89 and if that's ok run on that for awhile. If you're interested in my thread on the subject (and some real good advice as well as a bit of flaming :o , go to http://us.lexusownersclub.com/forums/index...showtopic=15169

They didn't give me error codes - they ony gave me the worksheet they used to tally the cost: 1.5 hrs Air Flow Meter Bad $325 ($168 parts incl) 1.5 hrs Bank 1, Sensor 1 AF Bad 1.5 hrs Bank 2, Sensor 1 AF Bad $920 ($566 parts incl) <-- both bank sensors The Lights are extinguished (they actually went out before my wife took the car in) I did have them clean and flush the throttle body/fuel system and the car seems to be running well. Keeping my fingers crossed that this was the problem. I'm going to have the sensors re-tested next Wednesday.

SKPerformance, Can you tell me what a motorvac is? Thanks

Thanks guys

Thanks for the comments guys. The Check Engine light has gone out and I plan on monitoring fuel consumption. I also plan on checking into mechanics around my area who are competent if not certified Lexus/Toyota. What I will not do is pay a mechanic $200 an hour plus parts at a 100% markup. Not in this lifetime.

Thanks Hammer! I kinda felt the same way and am royally *BLEEP*ed at the dealership for trying to involuntarily copulate with me! As to the gas mileage, I don't know -- it's the wife's car and she isn't interested in keeping records. She did tell me that she thought that she was filling up more often. Of course her 30 mile commute to her new job might have something to do with that. At any rate, I told her that for the next few months, she has to keep track of the mileage, so I'll report back later. In the meanwhile, thanks for the advice, that's pretty much what I was thinking since the light went out. It might save me a bunch of moolah. If ya get to Baltimore, look me up and I'll buy you a beer or three.

OK Folks, This is my first time on here, so be gentle. Bought my wife a Certified Pre-Owned 2000 ES-300 in 2001 and she has loved this car like no other. It has given her few problems and she loves driving it. The car now has 75,000 miles on it. However, on a recent road trip, she noticed some light knocking from under the hood under load. She thought she might have gotten a bad tank of gas as she had stopped at an EL CHEAPO filling station along the way. At any rate, after filling the tank with a higher octane fuel, the knocking seemed to go away and returned only occasionally and with no discernable pattern. A month later, the Check Engine AND the Traction Control Caution lights illuminated. They went out after refilling the car, but she wanted to have it checked out anyway, so she took it to our friendly Lexus Dealer. They did their magic and diagnosed the car with the following problems: Air Flow Meter - BAD Bank1, Sensor1 Air Flow Sensor - BAD Bank2, Sensor1 Air Flow Sensor - BAD And then they told me what it was going to cost to fix it. Now I need to replace my own personal Head Gasket because (drum roll please)... the quoted price to replace these three sensors is: $1245 US !!! ($283 each for the bank sensors, $168 for the Air Flow Meter, and the rest is labor) I told them to button the car back up, don't do anything to it and I'd get back to them later. I also told the guy he ought to come to my house and paint the damned thing for that kind of money. I think he felt I was being a bit of an !Removed!. At any rate, I've seen some comments about this kind of problem before, but if any of you are experts, I'd appreciate a bit of advice. I'm thinking of farming this problem out to the local Goodyear service center - or even attempting the fix myself. All replies are welcomed. Thanks Much, Al Greene g4driver night56owl@yahoo.com