So on to the base map tuning and our dyno results... we
used Scott Siegel's 1990 ex-Spec Miata for this purpose, which is nearly bone
stock with the exception of a Racing Beat intake, and still has the factory
flapper AFM in place. With the stock ECU in place we advanced the timing
to 14 degrees base timing and did a couple baseline pulls on the stock ECU which
netted the best power we were able to get from it. I wanted to compare the best
the MS could do with the best the stocker could do, not some skewed 8 degrees of
timing versus a perfectly dialed in map to make it look spectacular. Keep
in mind stock timing for a manual tranny 1.6 car is 10 degrees and going from
10-14 degrees makes a little difference on these cars when N/A, so if you're
running stock timing you'd see even 'slightly' bigger gains than what we'll show
Everything was done on 93 octane pump gas.
Next comes the MegaSquirt-- I spent about 20 minutes installing it, we set the base timing and started dialing it in. We steady state tuned both the fuel and then the ignition map, then we started the ramp runs to dial in WOT. Long story short... 8ft/lbs-tq gains in the low rev range, 2-4 everywhere else. 95ft/lbs peak tq versus just under 91 on the stocker. As for WHP, 1-5 whp gain everywhere in the rev range, from idle to redline, with a 5whp increase at peak. 105 versus 100 on the stocker.
You'll notice on the chart a dip at 4500rpm... what you're really seeing there is not a dip, but a big spike just before that at 3700rpm that makes it look like a dip afterwards. Scott had seen this on other Miatas and thought nothing of it because of that. At any rate later in the day we pulled off the AFM to see what kind of difference it would make... Wow... Let's just say you're going to want to pull off your AFM. First off that 3700 torque peak goes away the second you pull it off and turns into a nice linear torque curve up to the real peak at 5700. If you liked that first bump that may sound bad at first, but your torque everywhere else, particularly down low just off idle just JUMPS up a few more points and it stays higher across the board. That's going to do a LOT more for the overall performance of the car than that spike at 3700 that quickly disappears. I didn't grab a chart of this because we didn't tune it in yet and it would need to be tuned for since the torque spike disappearing caused a big rich spot in that area of the map where we had tuned for that torque spike at 3700. We'll go back and tune another map for that soon and make it available. Regardless of it getting a bit rich at 3700 though I drove home in the loaner Miata with the AFM removed on our new tune and it's night and day different from before -- compared to the stock ECU this thing really moves now... Since then we've run this map on several different cars including on our own '91 Miata that we've been daily driving and autocrossing... our results have been great, we strongly encourage you to dial it in for your car to make sure it's perfect for your situation however.
So is this the 'base map' that we're giving out with the ECU? Almost... we made a couple adjustments to err on the side of caution as we can't be sure you'll be able to run the same quality pump 93 octane we have, and we don't have any way to know the condition of your motor or what mods you might have. But do a little fine tuning and the power is there...
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