Second Generation Toyota MR2 Modifications
DIY Fuel Cut Defenser
Saturday, June 5th, 2004View the Online Guide
Cost: $15
Time: 30 minutes
Theory: There are two things that protect a turboed engine: a wastegate and fuel cut. A wastegate is supposed to regulate the amount of air that the turbo can spool up (for instance, it might allow 10psi and prevent it from going above that). What happens if the wastegate malfunctions? The turbo could spool up exponentially. Toyota realized this and set the ECU to provide a fuel-cutoff. If too much pressure is sensed (such as 12.8psi), the ECU stops providing fuel to the engine, effectively killing it. This is great to save an engine that won't be modified, but you want to modify this if you intend to increase boost. By creating a Fuel Cut Defencer (FCD) you modify the amount of power that gets to the ECU circuit which triggers fuel cut. By providing resistance, less power gets to the ECU, so it will not cut the engine off at that lower level.
Opinion: This is absolutely necessary when trying to gain more power from an MR2. You can easily eliminate fuel cut, but that can cause some serious problems if your wastegate malfunctions. Since companies like HKS sell their FCD for $125 or so, a homemade one is definitely a much cheaper alternative.