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.
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.
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.
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.
Since 1996, original equipment manufacturers have been using R-134a in all automotive air conditioning systems. R-134a is now the refrigerant of choice. This short article will help you learn proper safety procedures regarding the use of R-134a. Also, to stress the importance of refrigerant identification for OEM automotive A/C systems, we will explain some of the specific system component changes, and discuss important changes to A/C service equipment.
You may already be familiar with R-134a, A/C retrofits, and proper procedures. If you are confident of your abilities and retrofit knowledge, try answering the 20 question quiz that ends this article. If you are not sure about your R-134a retrofit knowledge, read this article first.
R-134a A/C refrigerant guide for Subaru cars: Since 1996, original equipment manufacturers have been using R-134a in all automotive air conditioning systems. R-134a is now the refrigerant of choice.
What Is R-134a?
R-134a does not contain suspected ozone-depleting chlorofluorocarbons. The chemical compounds and molecular structures of the old refrigerant R-12 and the new refrigerant R-134a are completely different. However, the temperature/pressure relationships of the two are very similar. Automotive publications, equipment manufacturers, and refrigerant suppliers, provide technical specifications and properties for R-134a.
R-134a and R-12 are not compatible. Under no circumstances should they be mixed. Vehicle and service manufacturers have gone to great lengths to prevent cross-charging or contamination of these two refrigerants. For instance, R-12 systems use a small high-side service port, and a large low-side service port. R-134a service fittings are completely different. The high side service port is now the larger of the two. These quick disconnect fittings will not work with R-12 service equipment.
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.
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.
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.
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.
Wheel arch height (vehicle ride height) as well as front and rear wheel alignment should be inspected at 30 month/30,000 mile intervals. Winter driving and its attendant chuckholes may shorten that maintenance interval for some drivers
While inspecting wheel alignment, also check for obvious signs of damage to suspension components, tightness of bolts and nuts and the condition of other under car components.
Check, adjust and/or measure wheel alignment in accordance with the following procedures:
1.) Wheel arch height (front and rear)
2.) Camber (front and rear)
3.) Caster (front)
4.) Front toe-in
5.) Rear toe-in
6.) Thrust angle (rear)
7.) Wheel steering angle
1. Wheel Arch Height
1.) Adjust the tire pressures to specifications.
2.) Set the vehicle under “curb weight” conditions (empty luggage compartment, install spare tire, jack, service tools, and top off fuel tank).
3.) Set steering wheel in a wheel-forward position.
4.) Suspend a thread from the wheel arch (point “A” in figure above) to determine a point directly above the center of the spindle.
Subaru Wheel Alignment: Measure the distance between the measuring point and the center of the spindle.
5.) Measure the distance between the measuring point and the center of the spindle.
6.) Consult the service manual for Wheel Arch Height specifications.
The first versions of the 2.5 liter twin cam engines employed non-hydraulic valve actuation. Like the timing belt, the clearance between the engine valves and the shim and bucket valve actuators does not require inspection and/or adjustment until 105,000 miles have elapsed. However, various circumstances may require an adjustment before that milestone is reached.
Valve Adjustment: Unlike some overhead cam engines that require you to rotate the cam until each cam lobe is facing 180 degrees away from the adjustment shim, Subaru has very specific procedures for adjusting four valves at a time (a pair of intakes and a pair of exhausts).
Clearance is tight and there is little room to work between the cylinder heads and the left and right frame rails. A special tool (ST 49818700) is available for depressing the valves and removing the adjusting shims. Without this tool, the job is impossible to accomplish with the engine in the car. Once again, we had the benefit of working on an engine that had already been removed from the car. Before you can adjust the valves, the engine must be cold. Consult the service manual to determine the parts that will need to be moved or removed to make some room to work.
Unlike some overhead cam engines that require you to rotate the cam until each cam lobe is facing 180 degrees away from the adjustment shim, Subaru has very specific procedures for adjusting four valves at a time (a pair of intakes and a pair of exhausts). The pairs of intakes and exhausts are never for the same cylinder, which makes things rather interesting. This system requires you to turn the crankshaft a total of four times to complete the adjustment procedure.
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