Introduction

This page details the Toyota 2JZ-GTE engines sequential turbo system.

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Checking 2JZGTE Sequential System

Introduction

I feel that the operation of the 2JZGTE Sequential Turbo system isn't fully understood by many, and when the system malfunctions many people have issues diagnosing the problem.

I've put together this information to hopefully help people to find and fix issues with their sequential turbo system.  

This guide details how to test the VSVs and the Actuators for the Sequential turbo system, a failure of which is usually the cause for low boost / sequential system malfunction.

I won't go into how the sequential system works, there are other places that explain that.
e.g. http://www.max-boost.co.uk/max-boost/supra/turbo.htm

This information is based off TSRM (Toyota Service & Repair Manual) http://www.turbosupras.com/pages/en/pages/technical/a80tsrm.htm and http://www.mkiv.com/manual/index.html for JZA80 for the most part.

Block Diagram

The below figure identifies the items to be tested, and shows locations.

VSV for Wastegate Valve

VSV for Exhaust Gas Control Valve

VSV for Intake Air Control Valve

VSV for Exhaust Bypass

Intake Air Control Valve Actuator

Exhaust Gas Control Valve Actuator

Pressure Tank Testing

Note this can also be tested in a different fashion by achieving boost, and then pulling a boost line that goes to a VSV off, e.g. IACV.  If the pressure tank is working a release of pressure when you remove the line should result.

Wastegate Actuator

Blow Off Valve Testing

Exhaust Bypass Actuator

Advanced Testing Notes

It is possible to test say the Intake Air Control Valve (IACV) without removing the VSV for the IACV.  Below describes how.  This same test method can be used for the Exhaust Gas Control Valve.

E.g.

• Remove Hose from IACV VSV that comes from the Pressure Tank
• Use a small plastic syringe to apply pressure (The IACV should not open with the VSV unpowered)
• Power the IACV and the pressure from the syringe should cause the IACV Actuator to actuate / move (The system should hold pressure / not leak)
• Remove power from the IACV VSV and the pressure should be vented by the VSV and the actuator should close.

System Still Doesn't Work

If the sequential turbo system still doesn't work after checking the above items then there are a number of things that might be wrong still

• No Power to VSVs
• No Engine ECU signal to VSVs (Broken wires / plugs / ECU etc)
• Damaged turbos (I.e. rear turbo with no turbine wheel)
• Damaged IACV, EGCV, Wastegate or Bypass Valve
• Large Boost Leak/s
• Incorrect Hose Routing
• Other

References

http://www.max-boost.co.uk/max-boost/supra/turbo.htm

http://www.turbosupras.com/pages/en/pages/technical/a80tsrm.htm

http://www.mkiv.com/manual/index.html

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