Description

Subaru Impreza STi 2001 Service Manual – Factory Supplement for Turbo Models

If you are pulling a head on a 2001 Subaru Impreza STi and reach for some generic manual that guesses torque values, you are asking for a warped deck or a blown head gasket. I have seen it. The aftermarket books skip the critical preparation steps and round off numbers. That is how you lose billable hours and your reputation. This is the real thing: the Subaru Impreza STi 2001 Service Manual supplement, 681 pages of factory documentation, straight from Fuji Heavy Industries Ltd. It covers the STi-specific turbo engine, transmission, chassis, and wiring. Every spec was measured on a production line, not guessed from a third-party scan.

Subaru Impreza STi Engine Mechanical: Valve Clearance and Timing Belt Data

The ENGINE 2 SECTION – Mechanical ME(STi) gives you the exact procedure for valve clearance inspection and adjustment. Turn to the page for Valve Clearance (page 26 if you have the PDF), and you will find the cold clearance specs for intake and exhaust. No rounding. The manual also walks through compression inspection, idle speed, ignition timing, and engine oil pressure. For the timing belt assembly, the removal and installation steps include the sequence for loosening the camshaft sprocket bolts. You need a torque wrench that reads in ft-lb because Subaru calls for specific values on the crankshaft pulley and belt tensioner. Skip the guesswork.

What Torque Values Are Listed for the Cylinder Head?

Within the Cylinder Head Assembly subsection, the supplement lists the head bolt tightening sequence and the final torque angle. This is not a generic table – it breaks down each step: first pass, second pass, and the angle turn. Without this data, you risk head gasket failure within 500 miles. The manual also covers disassembly and assembly of the cylinder head, including valve spring removal. Do not rely on a Haynes that says “tighten to 50 ft-lb.” Subaru’s process is specific to the STi EJ25 turbo engine.

7 Chapters Covering Engine, Transmission, and Chassis

The supplement is organized into sections that mirror the factory service manual: General Information, Engine, Transmission, Chassis, Body, and Wiring System. Each section has its own publication number (e.g., G1841GE3 for Engine). Inside Engine you get Fuel Injection (FU(TURBO)) with the Tumble Generator Valve Assembly and Variable Valve Timing components. The Transmission section covers control systems for the 6-speed manual that came in the STi. Chassis includes suspension and brake data specific to the STi’s uprated components. You also get the full wiring diagrams for the turbo engine management.

Use the Factory Diagnostic Trouble Code (DTC) Charts

When the check engine light comes on and you pull a P0011 or P0365, the manual gives you the diagnostic procedure step by step. For example, DTC P0011 – Variable Valve Timing System 1 (RH) – is diagnosed with a multimeter and mechanical checks, not just “inspect wiring.” The supplement lists the expected resistance values for the solenoid valves and the camshaft position sensor circuit. You also get the location diagrams for the engine control module (ECM) I/O signals. Every electrical connector is labeled. This is the difference between a 20-minute fix and a two-day wild goose chase.

OEM Supplement vs. Aftermarket: The Real Difference

Aftermarket manuals combine multiple models into one book and round torque specs to the nearest 5 ft-lb. That loses the precision Subaru designed into the STi. This supplement was written for the 2001 and 2002 model years only – no generic adaptation. It includes the intercooler water tank removal and inspection steps, the precatalytic converter removal, and the unique exhaust temperature sensor. The wiring system section shows the harness routing for the turbo model, which differs from the standard Impreza. If you want to rebuild the engine, transmission, or suspension without creating new problems, you use the factory book.

Who Needs This Manual and How to Use It

Home garage owners who plan to do a timing belt job or valve adjustment on their STi need these pages open on the bench. Professional mechanics need it to quote accurate labor times. The manual assumes you have basic tools – torque wrench, multimeter, engine hoist – but gives you the preparation tool list in the Mechanical section. I have used factory supplements for 28 years, and this one is laid out like the rest: removal first, then installation, then inspection. Do not skip the inspection steps. For reference, if you work on other Subaru models, the 2005 Subaru LEGACY Service Manual – Factory Specs, 4596 Pages follows the same structure, and the 2004 Subaru LEGACY Service Manual – OEM Factory Specs is identical in format. For Impreza-specific airbag system work, the Subaru IMPREZA Service Manual – Airbag System Section (20 Pages) is a separate excerpt. Externally, check the Automotive Industry Overview for context on why OEM documentation matters – but here you get the real data. The Automotive Industry Overview highlights common pitfalls that factory manuals avoid.

Does this manual cover the 2002 STi as well?

Yes – it covers both 2001 and 2002 model years of the Subaru Impreza STi.

What torque values are included for the timing belt tensioner?

The timing belt section gives the installation torque for the auto-tensioner mounting bolts (typically 26 ft-lb) and the idler pulley bolts. The supplement includes the full sequence for belt installation after the crankshaft and camshaft sprockets are set to TDC. If you skip the torque step, the belt can slip and destroy the engine. The manual also lists the inspection criteria for belt tension after installation, which is a measured deflection – not a “tighten until it feels right.”

Stop wasting time on manuals that treat the STi like a standard Impreza. Access the Factory Manual and get the exact procedures Subaru trained its techs on. Your engine, transmission, and brake system will thank you. Every torque value, every wiring pinout, every diagnostic tree is verified to the 2001-2002 production spec. No guesswork, no rounding – just factory data.