Hey gang,
every time temperature get over 83 degrees out side the engine pings for a second between random gear shifts. I'm run 91 octane and even if i have octane booster it still pings. I'm running 38/36 psi front/ rear tires, and the only mod i have is the k&N factory air filter replacement. I have heard of the MAF sensor getting gummed up but i don't have a decrease in gas millage or a loss of performance. My valves are quiet and engine runs smooth, so i don't think it needs a valve job yet...but i do have 25,000 miles. If any one has heard any thing please let me know.

where are you buying your gasoline? it could be cheap low grade spot gas. or maybe your injectors are clogging, so they aren't getting enough fuel and running lean, maybe run some complete fuel system cleaner through your engine.

spark knock from the 91 octane advance the ignition timing a bit, or add a little gap to your plugs or just go back to 87

that doesn't make sense, but your tire pressure is WAY to high. Check the driver door for the proper pressue...

i had the same problem in my mustang when i ran a 93 octane the timing wasnt advanced enough for the high octane and it pinged like crazy

i had the same problem in my mustang when i ran a 93 octane the timing wasnt advanced enough for the high octane and it pinged like crazy We cant mess with our timming, like you were able to on older cars. Everything on our cars are too computerized :ponder:

true, thats why I gave other solutions

Okay lets see her, I'm Cali ( so i know the gas is the worst here) but i buy Mobil 91 cuz i found that the car runs smoothest and strongest with it. about the plugs im going to check them and check the gap size cuz that could be a possibility. Ill try and fill up with 87 next week and see if it helps, but i hate it cuz last time i ran 87 the engine vibrated a lot and lost Torque. Tire pressure well i do a lot of canyon runs and have experimented for months trying to find a perfect pressure. found that this tire pressure with the tires i have are perfect.

ps thanks for the great reply guys

try a mid grade if 87 isnt making the engine run well, since it is just in the shifts

...your tire pressure is WAY to high. Check the driver door for the proper pressue...
No, it's not. Guess you've never done any 'performance' driving and/or had better tires than stock. You should try it sometime, then try it again with more air than what the door sticker specifies, as you'd be surprised how much the performance can improve with a bit more pressure. I generally run 36F/32R on the tC, it sticks better and the tire wear is still even across the tread. The door sticker is a recommendation by Toyota/Scion, and a good guideline for peeps that don't know what they're doing.

I am having the same pinging noise under load (in gear and accelerating). I have used octane booster, fuel cleaner, 91 octane, 87 octane....only buy from Shell, chevron and 76. Any other ideas...it's really getting to worry me to be frank.

pull your plugs and check for a lean condition