I didn't ignore it. It's possible and fine if you want, however, the ECU will retard the timing like I said. This will result in a loss of performance. Also, the ECU will have to detect knock via the knock sensor before it retards the timing, therefore, the motor is already experiencing preignition for the ECU to take corrective measure.

Not going to be a problem under most cases, but why run any risks with detonation to save a few bucks on a $30,000 car? Even if you fill up once a week and let's say the difference in 3 bucks.. 156 bucks a year.. not exactly a large sum of money.

Now if Honda did what Toyota did with the 88-89 MR2 SC's then there'd be a simple solution for running 87 octane.. just flip a switch on the dash (which retarded the timing).. but Honda likely assumed that most owners would just put 91 or higher octane in it.

 

My S2000 has an extra pedal to the left of my brake pedal. Do I HAVE to use it?

 

Dave is correct. It's like tieing your shoes after they've been put on. They have to come undone for you to tie them. You don't just go down and retie them if they don't need it.

Um, yeah something like that

 

Playing devils advocate here... You used to have to change your oil every 3000 miles, now if you buy a BMW, you can go 15000...

In all seriousness, I think it's a little crass to say we're a bunch of rich kids giving the guy a hard time. I think it's fair to say a good percentage of us work pretty damn hard to be able to "splurge" on premium- not to mention afford the car itself.

Look at it this way, it's still about half of what it costs everywhere else. Enjoy $3 a gallon while it lasts.

Edit
If you want to take it EVEN further-- a guys wife called in on last weeks "Car Talk" (National Public Radio show.. Pretty funny, actually) He's a retired engineer. Guess what he does to save gas? Only fill up a quarter tank to save hauling around the weight of the other 3/4 of a tank of gas.... In theory this would work. (Except when you actually factor the stop and go of having to fill up 4 times as often)

To each his own.

 

Dude if you cant afford 2 extra bucks get a different car cheap ass!

 

as people have already stated.

if you put regular in, you have to suffer some detonation before the ECU retards the timing. the ECU is not magical and does not preemptively predict you used 87 octane.

even then, it will continue to "try" and get back to a normal timing mapping, so it will "test" every so often by slightly advancing until it detonates again, and then repeats the cycle.

this will cause the car to lose power, (duh, you're retarding the timing) and also possibly suffer a bit in gas mileage. i've seen burnt pistons from owners who used 87 octane on the car. not a pretty sight.


to answer someone else's question, yes even a stock S2000 on 94 octane will have some timing slightly pulled. it's because our knock sensors/ecu are practically paranoid. however, that doesn't mean that 87 won't cause any detonation before the ECU retards the timing even more.

 

Thanks for the info. I just wanted to say that I wasn't saying that 87 or 89 was OK. My original posts are on the first page of this thread. Can anyone elaborate on how a Honda knock sensor detects detonation, or is that tough to say because it's all proprietery stuff. Thanks again, last question, sorry for hijacking.

 

lol

 

Knock sensors are the same in general. To simplify and provide an example, they are simple piezo devices. They sense the shock caused by pre-ignition and create a signal that is sent to the ECU, the ECU then takes tha signal, processes it and retards the timing. As stated above, the ECU will then eventually increase the timing again until it pings again, then it starts all over.

A real world example is any non-radar alarm system. A lot of alarms use piezo devices for shock sensors, when the alarm brain gets the signal from it it analyzes the sine wave of the signal and determines whether it should give just a alert beep or start it's full wail.

 

My '00 S2K, '02 BMW, and '04 S4 all run fine on 89 octane. I haven't tried 87.
It isn't about what you can afford, it's about what works without paying extra
for no reason. Try it out.