"I recently purchased a '02 9.5 Linear with 80K on it. I'm friends with the previous owner and know for a fact that she's never put anything but regular (87 octane) gas in it and experienced no performance problems save one time when it surged momentarily in 5th gear (it's a standard). In the two weeks that I've had the car, the surging, or hiccupping, or whatever you might call it has come on strong. It's always had regular maintenance, oil changes every 3K, and I just changed the oil myself last week. I know - now that I looked at the damned thing! - that the book says to use at least 90 octane gas, which I will if I absolutely have to, but does the condition described above sound like it was caused, all of a sudden, by improper gas usage? I just put my first tank of 89 octane gas - hoping for the best - in this morning and see no changes. Yet.
Opine, please."
Many opinions ensued. I uprgraded my gas (alternating between fill-ups of midgrade and premium) and I did change the plugs to the NKG, or NGK, or whatever it is, brand. The surging abated somewhat, but not entirely, and I also experienced some fairly enthusiastic high speed chugging and bucking which, as we were about 150 miles from the ancestral home, gave my wife and I quite a thrill. That passed - the chugging and the bucking, I mean... the thrill ain't gone - but I'd still get the occasional power surge/hiccup until, prior to giving the car to my son (I've picked up an '02 9.5 Aero), I brought the car in to the dealer for some much needed brake work.
When I came to pick up the car with my first born, they told me that they also replaced the DIC at no charge for one reason or another. And guess what? She's run smooth as buttered silk ever since. The boy even managed to get stopped for doing 49 in a 30 about two miles from the dealership.
We'll still run it with the good gas and proper plugs but I do believe that the chugging/surging/bucking problem lied in the cassette.
Fingers are crossed, and I thank all for their earlier input.
Cheers,
Michael