soloist3

Quick question, I recently picked up an 08 IS350 with 56k miles on it (yes original). Anyway, the dealership gave me a full tank before I picked up the car, "nice" I suppose, though figuring how cheap most dealers are, I assumed they threw 87 (regular) in there. My first thought, ok, better not do any spirited driving until I can empty the tank at least half way. In short, I empty the tank half way and quickly get to a top tier gas station and put 91 in (the highest we have in AZ). About a week later I am driving the car and decide to downshift into 3rd (from 5th) and go nearly wide open throttle, right as the car gets going I hear what I think sounds like pinging for maybe a second right at about 3500rpm. Now I have done partial WOT with the same gas with no issue, so I figured a downshift into 3rd would put the car fairly high in the rev range (3000-3500rpms is nowhere near lugging the engine in 3rd) so I thought I would be totally fine. My first thought is "did I really just hear pinging?", my second thought was maybe with the VDIM off I slightly spun the tires. Either way, this has me fairly well consumed with anxiety, as I haven't heard pinging from a car in probably 10 years (the last time I heard it was going up a steep hill with a 1991 Ford Explorer with 300k original miles on it and 87 in the tank). Anyway, all I can think about are the con-rods and ring lands and the potential damage that was done to this "pristine machine" that is my new IS350. I know engines can handle some amount of pinging, so this is pretty unrealistic, but I am just curious, has anyone ever experienced pinging on their IS350? I thought that the knock sensors were fairly sensitive to pinging and would pull timing in an instant so that you would never really hear pinging in this day and age. In the past I have put 87 in my Acura Legend and subsequent Infiniti I30 in emergency situations (both had knock sensors) with no issue (even on hot 110+ degree days), I guess I am really surprised and just trying to console myself with the delusion that what I heard was perhaps something other than pinging. Ah the stress of owning your "dream car"...yes the 2008 IS350 is my dream car...I LOVE this car.

Last thing, I got through another half of a tank as of yesterday and just filled up with more top tier 91 octane gas, though of course I didn't empty the tank completely, meaning there still might be some 87 in there (if that's what they put in there). Would it be worth putting in some octane booster for peace of mind? If so, what brand/product? I am really leery of putting questionable fuel additives in the car, but if there is something "tried and true" that could get me through this full tank I wouldn't mind springing for it.

cruzinZ

Do you have any modifications to your car? Is it completly stock? Knock sensors only work after detonation has occurred. Knock sensors only prevent further damage to the engine.

soloist3

No mods at all, this is simply the wrong car for modifying IMO :-) Well, of course the knock sensors would work after the knock event, but I guess what I was thinking was that it would likely have picked up on very subtle knocks throughout the week and retarded timing appropriately. To go from no knocking to fairly audible knocking seems odd in this day, especially since what I did was not too far off from what I had done earlier in the week (the occasional downshift to pass, etc..).

cruzinZ

The only time it would retard timing is if it senses knocking. I'm not sure what kind of safety measures were built into the vehicles system for retarding the timing. Some cars will reset after they are shut off and turned back on again. Once the knock sensor is tripped it will retard timing again. Other vehicles have a more sophisticated system that monitors the engine and will adjust the timing back to normal operating parameters.

Glad you realize this is the wrong car to modify. I just had to ask because too many people do stupid things. I've seen it way too many times in the world of turbo cars.

Rereading your first message I don't think you should worry about octane additives. You've pretty much diluted what ever 87 was in there. Just to be sure I would take it easy on the next tank and run it nearly empty. Wait until your light comes on before heading to the gas station. This way the following tank will have 91. At the pump there is only two grades of gas. Low and high. The middle grade is just a mixture of the two that is done at the pump.

If you still have problems after this with a fresh tank of 91 I think you have a different issue & one that stumps me. On a stock engine the only way you'd get pining would be from low octane fuel or an engine that was spec'ed for another region. Europe typically sells 98 and Japan you will find 100 or better.

Hope that your theory of dealer putting in cheap gas solves your issue. Let us know how the next tank of fuel goes.

cruzinZ

One other thing about toyota/Lexus they are very conservative on their factory tuning. They have a reputation to uphold and that is on reliability and longevity. I'm positive they could squeeze out quite a bit more power out of the IS250/350 but it would come at the expense of reliability.

It sucks for the tuners not having an open platform to build upon. But it's great for all of the second hand owners not getting stuck with some prior owners "put back to stock" & ready to blow up. I for one would never want to buy somebody's modified car due to the uncertanty.

UniSlayEX

As one who has the same model with a few more miles, I wouldn't have tried "burning" the fuel. The vehicle will know it has less umph and act accordingly. I had the same fear after the TISB.

The last comment mentioning to wait until the light comes on is exactly what I did and would recommend the same. Furthermore, I think trying to replicate the issue should be avoided until after your 3/4 done with that tank. That way, you can know for sure if the vehicle is experiencing and retardation. By that next tank you should know if something's the matter.

Just my two cents.

soloist3

Yep, that is the plan, I wasn't trying to induce it by doing a close-to WOT. I was just trying to remind myself of why I bought the car, drive a little spirited. I haven't pushed it since but I also haven't slept well with the sound of "could be" knocking in my head. I am going to put in a few gallons of 101 octane after 4-5 gallons is through, just to be on the safe side. Otherwise, I have been driving in snow mode ever since the "incident"...it changes throttle tip-in, timing, and TPS values for me so I don't forget that I am trying to avoid "pushing it" with possible bad gas :-)

Gville350

iTrader: (10)

Make sure it's unleaded 101. Or look into www.race-gas.com

soloist3

Bought 2 gallons of 100 unleaded, haven't heard anything since. I am going to run this tank out before pushing the car hard, but so far it feels faster so it is probably adding more timing advance, which is a good thing.