After driving the Miata around on a few trips this past week I have come to to the conclusion that the muffler itself is not the cause of the harsh exhaust note at high throttle levels. Maybe we didn’t notice it so much on Donna and my short test drive last weekend because of the already slightly louder note of the Borla. But now it seems to me that it really comes about once the car has gotten totally warmed up.
So while the sound of the Miata at start up in the garage with the Borla muffler is positively sublime, kind of barks a little like the half of a Ferrari V8 it is, I pulled it off and put the Racing Beat back on.
At full operating temperature not only does the sound get ugly, but my uncalibrated butt dyno is telling me that I’m not getting the power I once was at lower RPMs. I’m not sure whether this is an outlier or a further symptom of the Emperor’s problems, but at the last fill-up the gas mileage was just under 21 MPG, which is the second lowest figure ever since I started keeping track back in December of 2012.
The problem has got to be in the VVT system somewhere. A clogged filter or line I’m already working on with the addition of the Italian (Rotella) oil. On the Forum I’ve found some instructions on testing the oil control valve to see if it is working. While I don’t think this is it, because I do get the telltale rev surge at 3500-4000 the first couple of times in the morning when just starting out, it still needs to be done to eliminate it as a possibility.
Miata Top Transitions since 06/25/15: 170
Time for new Miata?
Yeah, probably. But I feel a little like Zira in “The Planet of the Apes” when George Taylor asks to kiss her, when she tells him, “All right, but you’re so damned ugly.”