GUIDE TO FITTING
1 Technician Marius sets to work strapping down the car on the rolling road and aiming a fan at the front of the car. First job was to establish what power the car produced with its standard ECU. It usually takes three runs to establish if all is OK (power should be within one or two bhp), but peak power was all over the place, from 106.6bhp to a high of 115.2bhp after seven runs. The cam angle sensor was checked – if loose it can cause the power to fluctuate – but all was well.
2 This car had been subject to a 14-degree timing modification, a popular tweak but one that we’ve been advised to not bother with. This was reset to standard and instantly cured some running problems, with three consistent runs at a peak 117.6bhp, or a 2.4bhp improvement, but still 15.4bhp less than the 133bhp the 1.8-litre car should have had when new in 1997. Resetting the timing also removed some flat-spotting.
4 Drill two holes in the ECU’S protective casing for the vacuum line that reads manifold pressure and the lead to plug into your laptop. If you turbocharge or supercharge your car you’ll need to know manifold pressure at all times. When Mazda built the car it put a vacuum pipe outlet on the manifold because it knew aftermarket tuners would fit turbochargers.
6 Matt Thorne (boss of Motorsports Electronics) takes over and adjusts the ECU’S basic settings on a laptop. The cable for the laptop lives inside the footwell with the new ECU (or, should you need more regular access, inside the glovebox). Note that it’s not currently compatible with a Mac laptop.
3 Now that we had an initial power figure, the ECU was removed from the passenger footwell. Access is simple – unscrew the door sill trim, pull up the floor carpet and reveal the footrest. We’re now ready to install the new ECU.
5 The ECU slots straight in and with the base map already set up, it’s ready to drive without any tuning. However, our plan is to take advantage of some of the tuning possibilities afforded by the ME221.
7 If your car is to remain naturally aspirated, then the minimum requirement to make the most of the replacement ECU is a cone air filter on the end of a simple pipe and a four-into-one exhaust manifold. As our photographic car is likely to be turbocharged in the future, there wasn’t any point fitting manifold and filter just for the purposes of this story. The compromise was to remove the existing air filter’s piping, resulting in an increase of peak power to 124bhp. Power was up right across the rev range, with a surge between 3000 and 4500rpm, giving 10bhp and 15lb ft of torque extra over standard, developed at 3500rpm. Matt estimates the car would achieve 125–130bhp with a cone air filter and the four-into-one manifold fitted.