Project: 1995 Miata

[Jake]

Post-VIR "Heat Wave" Update: 119,200 miles (1,100 on the swap)

Other than the pain of leaving Northern Virginia at 5 PM on Thursday to go south with everyone else who commutes from too-far-away to work up here, the drive to VIR was pretty pleasant. I ran the AC for the first two hours - very glad I kept it after the swap - and dropped the top in Charlottesville. The motor is rev-happy and feels strong. Over the ~220 mile drive, I managed 29 mpg, even with the AC running part-time. Not bad at all, although five hours of this does get tiring:



Friday and Saturday had everything running great. A few rattles and such, but nothing strange. On the "run from time trials" pace laps, I was able to get up to 105ish easily. Well, as easily as a Miata can Even in the super-hot weather, A/C on or off, it was staying right where it should on the temp gauge:



Maeng went out with me on Sunday in HPDE 3, to evaluate my driving for a Time Trials license (which, I believe I did pass, yay!). We got probably four laps in with some good speed on the straightaways (100+ mph). The fifth lap, I felt a noticeable lack in power and could do just shy of 90, max. Engine temp creeped up by about a needle's width above the center mark. This was around Turn 2, so we had to make a full lap anyway to pull in. At T3, I stopped for a red flag drill. As soon as I stopped (clutch depressed, 0 mph), the engine just gently cut itself off. I restarted it, and the same thing happened. Had to give it throttle (just a quick blip) to make the ECU realize "hey moron, need to you idle here" and then it was idling fine again.

We came in after that red flag drill. I've posted to Reddit and Miata.net, and the common thoughts are "new thermostat" and "different coolant mixture, with Water Wetter added." The T-Stat is lord-knows-how-old -- it came with the 99 motor -- and I'm running 50/50 pre-mix coolant. Someone suggested 70/30 mixture with WW on top of that. He also mentioned that the ECU will automatically retard timing in extreme heat, which is what this felt like.

Track/Miata folks, any thoughts?

The CEL is still on for the EGR shit that I haven't taken care of yet.