I was very specific in saying that we can't reduce this debate to "My car has 210,000miles on it, can I use 87 octane?" While 137k isn't a LOT you obviously had other sensor issues. The same applies to dang near anything with cars. "Can I use a 50shot of nitrous?" - "As long as your injectors work right." - "Can I use 1.9 rockers?" - "As long as your springs work right." la de da..see what I'm saying? This only applies to a properly working engine.

If your MAF was malfunctioning and you were detonating chances are you were running lean, overheating the cylinder, and detonating from that. While higher octane would help SOME, it wasen't the fault of the octane and hence is not relevant to our debate.

"Another one bites the dust...dun dun dun...Another one bites the dust...dun dun dun..."

Man, I'm getting good at this thread killing thing aren't I?

DrJay,

You didn't kill the thread. It'* just in limbo right now. I'm in the process of doing my experiment, but it takes a long time between fillups for me (about 3 weeks). I already know 87 will reduce performance. I'm checking now to see how it affects my mild city driving gas mileage. I will report back in about 3 weeks. If I get pinging on my daily hill climb, I'll report on that too, sometime next week.

I love my Bonnie.....So I use quality filters, quality Oil. have her serviced, wash it every week, hand dry, wax once a month, service the transmission and change oil in the Superchager. Hell I even change the boost control solenoid filter every three months.

Now, after all of that.....why in the f*&^(^*%*k would I use crap gas in my pride and Joy? You want'a FLY, pay the price

ken

yclops:

I started my experiment with 87 octane, and so far, it still runs smooth. I didn't push it too hard, but I drove up a fairly steep hill at 50, and with the TCC locked up, I let it lug the engine until it shifted up, and I didn't hear any audible pinging or knocking. However, I also had my scantool hooked up, and it did detect a large amount of knocking , and appropriately cut the timing. This was on a very hot day as well, around 100. I also noticed that the idle timing was around 19 degrees, whereas with 91 octane, idle was at 25 degrees. This might be in part due to the temperature, which was much higher than when I did the reading with 91 octane.

Anyway, I will let it run to the next fillup before I report again, since my goal is really to see how it affects my MPG. I have a feeling with the cut timing, it may turn out to be a wash. Stay tuned, and check back in about 3 weeks.

I've done it. Depending on the driving conditions, it can vary. In hills and mountains, 87 octane gave me worse mileage. On the freeway at mild speeds, it was a wash. Never did 87 give me better mileage. Keep in mind that with my mods, particularly the chip, my car requires 92-93 octane now, 91 isn't enough any more. This was confirmed by Jet on the phone.

Hi Will,

That'* cool, but in my area, I can't find anything higher than 91. Anyway, with 91 I had a trickling of knocks when I went up that hill, but 87 gave me more of an avalanche of knocks, so it definitely makes a difference. Still, it was inaudible, so it sounds like the PCM is doing its job.

isn't slight spark knock under load advantageous?

Never.