The Boost Test for normal boost pattern and a method of testing is as follows:

Note this was originally developed for Mazda dealers, and has since been slightly modified as per feedback/questions from various people that have used this.

1) Steps should be done in order. Failure of any step will require further inspection prior to continuing.

• WOT = wide open throttle
• KOKO = Key On Key Off

2) Verify engine is at operating temperature.

• Remove Double Throttle Actuator vacuum line
• At operating temperature, no vacuum should be present with engine idling.
• Re-attach hose

3) Check engine vacuum at idle

• Vacuum reading should be above 15 inHg with Air Conditioner OFF. Typically 17 inHg to 19 inHg for a stock engine, and for a ported engine the vacuum readings are more in the 16 inHg range.

4) Check no-load operation of Primary Turbocharger, (note that the best way to test the car for boost is step 7, but you need to pass this test/step to be able to perform test 6).

• Briefly accelerate engine to WOT in neutral, (From idle, punch the gas [WOT], get the RPMs above 5,000 but less than redline), about +4 psi should be obtained as you pass from 3,000 to 4,000 RPM.
  • If you do not get this you most likely have a leak of the boosted air. Go through the Primary Turbocharger troubleshooting section.
• If get about +4 psi, then have another person watch the Turbo Pre-Control Actuator rod for movement during this test.

5) Check vacuum chamber's storage ability with engine off

• Pull off vacuum hose at Charge Relief Actuator
• Should hear air entering hose vacuum, re-attach hose
• Start engine - briefly accelerate engine to WOT in neutral again
• Turn engine off - KOKO 6 TIMES
• Watch Charge Control Actuator work each time
• Watch Turbo Control Actuator work each time, (need to crawl under the car to see this one)

6) Check Pressure Tank's pressure storage ability with engine off

• Pull off one of the hoses of Pressure Tank
• Should hear air leaving tank (pressure), re-attach hose.
  • There is a one-way check valve between the pressure tank and the Primary Compressor housing that feeds the pressure tank, this one-way check valve or a leaky hose or solenoid valve will cause Pressure Tank leakage.

7) Road test with boost gauge

• Drive to third gear with normal acceleration
• Accelerate from 35 MPH at WOT until passing 4,500 RPM
• A slight and smooth increase in power should be felt at approximately 4,500 RPM. This will be about 65 MPH.

These readings indicate normal operation. Readings will vary with altitude and temperature,

(i.e. lower temperature = higher boost / higher altittude = higher boost).

If you are having intermittent problems when hot, then try driving the car hard, parking the car, allow it to heat soak for a minute or two, perform these tests with everything very hot.