horrible. What should I do now? My owners manual says I'm supposed to put 91 or higher. Now it is knocking and chugging along whenever it's running. I'm only have a 1/4 tank left but now my check engine light and the TCS light is on.
Fill the tank ASAP with the highest available octane gas (the highest I've seen is 93). If 93 isn't available, then 91 octane at a minimum. The added fuel will dilute the remaining 87. Whenever there is room for a couple of gallons in the, refill again with 93 or 91 octane gas.
The engine management computer will sort things out after a bit of driving.
A better (more involved) procedure would be to remove the remaining gas from the tank, and then refill it, but that's not really necessary to go to that bother.
The issue with the lower octane gas is that it's not compatible with an engine that runs at a higher compression ratio. It's okay to use gas with an octane HIGHER than specified, but not LOWER.
The issue with the lower octane gas is that it's not compatible with engines that run at higher compression. The engine is pinging (pre-ignition), and the engine management computer is making adjustments to compensate as best it can. The best remedy is to feed the engine fuel with a net octane rating of 91 or higher.
BTW... don't bother adding an "octane booster" (readily available from any auto parts store willing to take your money in exchange for snake oil.) The most suitable "octane booster" to add in your situation would be toluene, also acceptable would be xylene. You can add, but the most important thing is getting a 91 or higher octane into the tank ASAP.
(Note that there are lots of reasons an engine will be "running horrible", other than lower octane gas causing pinging and the engine control module trying to compensate.)
I agree with Jeff, the octane is not your problem it's bad gas I'm sure! Make sure you buy gas somewhere else instead of Goober's watered-Down Gas Station. Go buy yourself a Bottle of cheap Octane Boost and fill your tank up with some good Gas somewhere. Be smart and don't buy Gas at Kwik Shop Stations or at BP stations. You do know that Hydrogen Gs like BP's Gas is watered down, Hydrogen=water (look it up) Today's Vehicles do not benefit Hydrogen so called Gas, maybe in the future but BP's Gas is a FARCE! Also actually look at your owners Manual I guarantee it doesn't say Only burn Premium Only. It's unlawful to sell Vehicles in the United States that Only burn PREMIUM. O and if you need to reset your ECM (Computer) Codes or Lights just unhook your Battery (Negative Post) for 30 Seconds and then Hook it back up. This will clear those Codes, but make sure to fix the Gas problem first.
Just fill up the tank with the correct octane fuel and see if it corrects the problem. Also see what the Check Engine Light code indicated, probably it will refer to the wrong type fuel.
Just fill up the tank with the correct octane fuel and see if it corrects the problem. Also see what the Check Engine Light code indicated, probably it will refer to the wrong type fuel.
Put a 1/4 tank of 93 octane in, this will balance the difference, Yo could also but octane booster but it's more expensive and really is no different, did the same thing with my audi, the 93 cleared it right up, one tank of 87 will cause no long term damage