Hey folks,
This one sure has me scratching my head. Every now and then I've decided to try running my 91 Loyale wagon (Fuel injected, SPFI, EA82) on 93 octane gas as opposed to the 87, and there's a noticeable loss in power with 93. Not too much (my butt dyno estimates about 5-10 HP), but it's there.
I'd have expected it to be no different or a little better, but after I got a faulty O2 sensor replaced in the y-pipe a while ago, last night I decided to see if there was any change. . nope. . car is still sluggish (well more than usual) on 93.
Any thoughts? The manual for the car says to use 87 octane *or higher*.