Although the MBC was incredibly helpful in bringing the Cappuccino’s boost back up to standard it seemed prone to spiking above safe boost levels at higher speeds, especially as I began to tweak the boost into N1 ECU territory. To get better control over boost levels in general – and to see if I could reduce or eliminate this spiking – I decided to have a look at Electronic Boost Controllers, eventually purchasing a HKS EVC III from JapanDyno (a very useful eBay shop!) for its period looks and relative cheapness.
The plumbing side of fitting the EVC was very simple thanks to the previous MBC installation – the solenoid was mounted in the same place and used the same bracket as the MBC, meaning that no adjustments to the piping to and from the turbo were necessary. The EVC solenoid does requires a third connection to a boost/vacuum source but this is easy to splice off from one of the connections on the intake side of the engine.
It’s also a good idea to purchase filters for each of the lines entering or leaving the solenoid in order to keep everything as clean as possible. They’re not cheap (I paid around £12 per filter) but cheaper than replacing the EVC!
With the solenoid position fixed it was now a case of running the wiring harness through the firewall and into the cabin. Down and behind the battery – tucked right into the passenger-side corner of the engine bay – is an existing wiring loom and hole which will also accommodate the EVC harness without too much trouble. This brings the harness out into the passenger footwell, ideal for me as I’d decided to mount my EVC in the glove box.
To power the EVC I decided to piggyback from the cigarette lighter connections rather than open up the car’s wiring loom – this is much simpler, requiring only a couple of connectors and no cuts into the original wiring.
With the installation complete all that was left was to find a long, straight, and quiet road in order to calibrate the turbo’s characteristics into the EVC memory – basically pulling off in 3rd gear at WOT 3 times, each time waiting for a beep from the EVC before slowing down. Not even moderate speeds are reached but it’s surprising how much road you need to be able to do this!