Category Archives: USDM

2.5RS, Drivetrain, Ej20, ej20G, EJ25, EJ257, forester, gc8, Impreza, Legacy, Old School Subaru, STi, Subaru, USDM, WRX

Knock Sensor diagnosis for Subaru

Knock Sensor diagnosis for Subaru:

This is a simple overview on diagnosing knock sensor issues with your Subaru Impreza/Forester/Legacy/Etc.

The knock sensor is designed to sense knocking signals from each cylinder. The knock sensor is a piezo-electric type element which converts knocking vibrations into electrical signals.
The knock sensor is designed to sense knocking signals from each cylinder. The knock sensor is a piezo-electric type element which converts knocking vibrations into electrical signals.

The knock sensor is designed to sense knocking signals from each cylinder. The knock sensor is a piezo-electric type element which converts knocking vibrations into electrical signals. The electrical signal is sent to the ECM, which changes the ignition timing to reduce the engine knock or ping. For this system to work correctly, the knock sensor must first hear the engine ping. The driver of the vehicle may also hear a small engine ping. A delay of approximately 1-2 seconds is normal, depending on the fuel quality, engine load, air temp, etc. At this time, the ECM will retard the timing.

This function can be viewed on the Select Monitor RTRD mode. When the knock is eliminated, the timing is gradually advanced to the specified setting. If engine ping is heard again this process is repeated. This will continue until the knock sensor no longer hears the engine knock or ping.

Note: This is a normal operation of the knock sensor. Do not try to repair it.

The next page will discuss asking the right questions on diagnosing knock sensor failures.

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Drivetrain, Ej20, EJ257, gc8, Impreza, JDM, Legacy, STi, Subaru, Turbo, USDM, WRX

Cool Down WRX Turbo Procedure

Cool Down WRX Turbo Procedure:

It is not necessary to perform a cool down/idling procedure on Subaru WRX turbo models, as was recommended with past turbo models. “The current 2.0 liter turbo engine has a far greater cooling capacity and, coupled with technology advances, makes this practice no longer necessary. This explains why information about a cool down is not included in the Impreza Owner’s Manual.

Cool Down WRX Turbo Procedure: It is not necessary to perform a “cool down/idling” procedure on Subaru WRX turbo models, as was recommended with past turbo models.
Cool Down WRX Turbo Procedure: It is not necessary to perform a “cool down/idling” procedure on Subaru WRX turbo models, as was recommended with past turbo models.

The heat contained in the turbocharger begins to vaporize the coolant at the turbocharger after the engine is stopped. This hot vapor then enters the coolant reservoir tank, which is the highest point of the coolant system.

At the same time the vapor exits the turbocharger, coolant supplied from the right bank cylinder head flows into the turbo. This action reduces the turbocharger temperature. This process will continue until the vaporizing action in the turbocharger has stopped or cooled down.

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2.5RS, Drivetrain, Ej20, EJ25, EJ257, forester, Impreza, STi, Subaru, Turbo, USDM, WRX

Engine noise when cold (Winter is coming)

Engine Noise When Cold:

Beginning with the 1997 model year, the 2.2 and 2.5 engines were made more fuel efficient, more powerful, and were given a flatter, more usable torque curve than in previous years. To achieve these objectives, it was necessary to make improvements and modifications to the Subaru engine lineup. The following are some of those improvements:

• Mechanical valve lash adjusters (reduces friction).
• Lightweight pistons (reduces inertia).
• Short skirt, Molybdenum coated pistons (reduces friction).
• Increased compression ratio (improved power output).
• Improved cylinder head design (improved cooling).
• Improved induction system (improved breathing).

Engine Noise when cold: As a result of these enhancements, some Subaru engines may exhibit some engine noise during the warm-up period after a cold startup.
Engine Noise when cold: As a result of these enhancements, some Subaru engines may exhibit some engine noise during the warm-up period after a cold startup.

As a result of these enhancements, some Subaru engines may exhibit some engine noise during the warm-up period after a cold startup. This engine noise is a consequence of the engine improvements and is not, in any way, an indication of any engine problem.

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2.5RS, AWD, Drivetrain, forester, gc8, Impreza, Legacy, STi, Tuning, Turbo, USDM, WRX

OBD-II Subaru Diagnostic Systems

OBD-II Subaru Diagnostic Systems:

The Environmental Protection Agency (EPA) now has regulations in place that establish requirements for on-board diagnostic (OBD-II) systems on light-duty vehicles and light-duty trucks. The purpose of the OBD-II system is to ensure proper emission control system operation for the vehicle’s lifetime by monitoring emission-related components and systems for deterioration and malfunction.

OBD-II Subaru Diagnostic Systems: The Environmental Protection Agency (EPA) now has regulations in place that establish requirements for on-board diagnostic (OBD-II) systems on light-duty vehicles and light-duty trucks.
OBD-II Subaru Diagnostic Systems:
The Environmental Protection Agency (EPA) now has regulations in place that establish requirements for on-board diagnostic (OBD-II) systems on light-duty vehicles and light-duty trucks.

There’s a big difference between detecting only hard faults (OBD-I) and having the ability to actively monitor the system for proper operation, deterioration or a malfunction (OBD-II).

Engines in today’s vehicles are largely electronically controlled. Sensors and actuators sense the operation of specific components (e.g., the oxygen sensor) and actuate others (e.g., the fuel injectors) to maintain optimal engine control. An on-board computer, known as the “powertrain control module,” controls all of these systems.

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forester, gc8, Impreza, Legacy, STi, Subaru, USDM, WRX

Part Number Decoder Subaru

Part Number Decoder:

For those of you who are interested, this is how Subaru breaks down a part number. This could help you guess a part number if one that you found on a part is missing digits or is damaged.

Part number decoder for Subaru: For those of you who are interested, this is how Subaru breaks down a part number.
Part number decoder for Subaru: For those of you who are interested, this is how Subaru breaks down a part number.

Genuine Part Classification Codes

A = Part Description Code
B = Part Sequential Code
C = Part Category Code
D = Specific Code
E = Modification Code
F = Color Code

Description of Genuine Part Classification Codes

A. Part Description Code: Identifies part name and function. If the first position is an alpha, it identifies an accessory.

B. Part Sequential Code: Sequential number system assigned to the part number by Fuji Engineering Division.

C. Part Category Code: Key position of the part number in determining the logic of the numbering system:
A = Engine and Transmission Parts
K = Engine and Transmission Parts
X = Some Automatic Transmission Parts
G = Body Parts

D. Specific Parts: Identifies specific characteristics of parts with the same part description code and designated sequences from A00. The specific code is assigned by the Fuji Engineering Division for internal use only.

E. Modification Code: Identifies an engineering change to the part. For example:
0 = original
1 = 1st modification
2 = 2nd modification
3 = 3rd modification

F. Part Color Code: Identifies color coded parts for digits 11 and 12. Digit 11 = color and digit 12 = degree.
Code E or F in the 12th digit is for Fuji Heavy Industries (FHI) internal purposes only.

Note: Code E or F in the 12th digit is for Fuji Heavy Industries (FHI) internal purposes only.

For example look at these rare 22B parts with their part numbers.

Part Name Part Number Quantity
22B Bolt Subaru 57728FA041 2
22B Bush B (L/Link) 20251AA050 1
22B Bushing Transverse Link Front ST2022044000 1
22B Bushing Transverse Link Rear ST2022044010 1
22B Clip Subaru 57728FA020 6
22B Fender 57110FA050 1
22B Fog Lamp Cover Set (LH and RH) S075580070 1 Set
22B Front Bumper Assembly S075580080 1
22B J Nut 57738KA000 2
22B Lateral Link Assy-F S075580140 1
22B Lateral Link Assy Rear RH S075580150 1
22B Lateral Link Assy Rear LH S075580160 1
22B License Plate Bracket S075580210 1
22B Pillow Ball Bushing 20252PA000 1
22B Seat Right Front 64101FA680 1
22B Seat Left Front 64101FA690 1
22B Seat Rear Cushion 64401FA410 1
22B Seat Rear Seatback 64451FA810 1
2.5RS, Drivetrain, Ej20, ej20G, EJ25, EJ257, forester, gc8, Impreza, JDM, STi, Subaru, Turbo, UK, USDM, WRX

Subaru Engine Block Piston Size Identifier:

Subaru Engine Block Piston Size Identifier:

The picture below of this paragraph shows the location of piston size and main journal size information on all Subaru engines. As the figure illustrates, it is possible to have more than one piston size in the same engine.

Subaru Engine Block Piston Size Identifier: The picture on the bottom shows the location of piston size and main journal size information on all Subaru engines. As the figure illustrates, it is possible to have more than one piston size in the same engine.
Subaru Engine Block Piston Size Identifier:
The picture on the bottom shows the location of piston size and main journal size information on all Subaru engines. As the figure illustrates, it is possible to have more than one piston size in the same engine.
2.5RS, forester, gc8, Impreza, STi, Subaru, UK, USDM, WRX

Electrical Grounding System inspection

Electrical Grounding System inspection:

The importance of checking electrical ground connections during any electrical troubleshooting cannot be over stressed. For example, a poor electrical ground at the radiator support or fender (depending on the affected Subaru model) may cause any or all of the following problems:

• The door ajar indicator light dims when the brake pedal is applied.

• There is a loss of communication with the Automatic Transmission side of the New Select Monitor when the vehicle is put into gear.

• The engine starts running poorly after driving only a few feet.

• There is a loss of communication with the Anti-lock Brake side of the New Select Monitor when the brake pedal is applied.

Vehicles that have been involved in accidents should be inspected especially closely. In the example below, a Subaru Legacy had been involved in a front end collision.

During reassembly of the vehicle, the electrical ground wire behind the left front headlight that fastens to the radiator support had not been reinstalled (refer to photo). This electrical ground is attached to the left front fender on Subaru Impreza and Forester models. After reinstalling this ground wire, all of the affected systems returned to proper working order.

Electrical Grounding System inspection: The importance of checking ground connections during any electrical troubleshooting cannot be over stressed.
Electrical Grounding System inspection: The importance of checking ground connections during any electrical troubleshooting cannot be over stressed.

 

2.5RS, AWD, Drivetrain, exhaust, forester, gc8, Impreza, Legacy, STi, Subaru, Suspension, Transmission, Turbo, UK, USDM, WRX

Maintenance Inspections for Subaru:

Maintenance Inspections for Subaru:

Subaru vehicles are more reliable than ever before. To assure their continued reliability, a schedule of inspection and maintenance (I & M) services is prescribed by Subaru of America for every Subaru vehicle sold. A copy of this schedule can be found in the Warranty and Maintenance Booklet located in the vehicle glove compartment.

Maintenance Inspections for Subaru: Subaru vehicles are more reliable than ever before. To assure their continued reliability, a schedule of inspection and maintenance (I & M) services is prescribed by Subaru of America for every Subaru vehicle sold.
Maintenance Inspections for Subaru:
Subaru vehicles are more reliable than ever before. To assure their continued reliability, a schedule of inspection and maintenance (I & M) services is prescribed by Subaru of America for every Subaru vehicle sold.

Subaru vehicle maintenance inspections services are divided into recommended intervals beginning with three months or 3000 miles (whichever comes first). Each additional level in the maintenance schedule (7,500/15,000/ 30,000 miles) adds more maintenance and inspection steps to the process. The 15,000 (15 month) and 30,000 mile (30 month) services are ‘major’ services, and include the most comprehensive range of component checks, part replacements and adjustments.

If you are already familiar with Subaru vehicles, you may have developed a routine when performing a vehicle safety maintenance inspections. Following a set routine allows you to start at one end of the vehicle and end up at the other end, having performed all of the necessary safety inspection steps along the way.

Repetition of the safety inspection may also allow you to commit the steps to memory, but a checklist can be a helpful addition that leaves nothing to chance (or memory). Checking items off the checklist provides a written record that can be shared with the customer and retained for your service records as well.

Recommended steps in a Subaru Safety Maintenance Inspections  are also spelled out in the owner’s Warranty and Maintenance Booklet. Some of the steps overlap services performed during the scheduled maintenance program. It could be argued that any scheduled maintenance should always include a Safety Inspection. Most of the Safety Maintenance Inspection steps are based on common sense, but it’s surprising how frequently these simple suggestions are ignored.

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