The heart of any vehicle is the engine. It’s what makes it go. Anything that jeopardizes the operation of the engine can have disastrous effects and result in extensive repairs. If the engine is the heart of the vehicle, then surely the cooling system is the “circulatory system” that keeps the engine operating at optimum temperatures. If it doesn’t, bad things are going to happen.
Subaru engines are modern masterpieces of technology and precision. Manufactured of multi-alloy metals and exotic materials, these engines contain more components, weigh less, produce more power and torque and are more durable than the old iron engines of 40 years ago. However, even these high-tech engines can be damaged or destroyed by excessively high internal temperatures.
Though more energy efficient than ever before, the combustion of fuel and air in the cylinders that produces the power that propels the vehicle still creates an enormous amount of waste heat. This is carried away from the cylinders either by venting it out through the exhaust system or via the cooling system. If either of these systems fail to keep the engine at normal operating temperatures, an overheating condition occurs. Of the two, the cooling system is most vulnerable.
The cooling system can easily be contaminated or compromised by anyone putting the wrong products into the radiator or reservoir. Often, Subaru owners or service facilities that are not aware of the specific needs of the vehicle will put incorrect chemicals into the system. In fact, according to figures published by the U. S. Department of Transportation, coolant-related problems are the primary cause of mechanical breakdowns on the highway. Many of these breakdowns could have been avoided by the use of proper coolant and the right additives.
A major component of the Subaru OBD-II system is the system’s ability to monitor the evaporative emissions system. Today’s vehicles are producing very low emissions from the tailpipe, so it has become increasingly important to monitor and contain emissions from other vehicle sources.
A potentially large source of emissions is the vehicle’s fuel system. If not properly contained, vapors escaping from the fuel tank could produce a larger quantity of harmful emissions while the vehicle was standing still than what would be emitted via the tailpipe when the engine was running and the vehicle was driving down the road.
The Subaru OBD-II system monitors the evaporative emissions system by drawing the system to a negative pressure. If the system holds vacuum, it passes the test. If the system fails to hold vacuum for the prescribed period, it fails and a diagnostic trouble code (DTC) P04440 is stored in the ECM memory. The malfunction indicator light (MIL) also comes on in the dash to alert the driver to the problem.
The charts that follow were collected through the data link connector using the New Select Monitor (NSM), during the diagnosis of a DTC P0440 on a 1997 Subaru Legacy 2.5 liter. We’ll begin with a description of system operation under normal operating conditions.
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 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.
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).
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.
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.
All late model Subaru four cylinder engines employ a “waste spark” ignition coil system. Each time the ignition coil fires, it provides a spark to two cylinders at exactly the same time. Since only one of the two cylinders is on the compression stroke when the coil fires, the spark to the second cylinder (which is on the exhaust stroke) is “wasted. ”
The ignition coil sits on top of the intake manifold and is divided into two halves. One half provides the spark to the number 1 and 2 cylinders, and the other half provides the spark to the number 3 and 4 cylinders. Instead of the familiar single secondary coil terminal, this coil has four secondary coil terminals.
Testing methods for this type of coil are slightly different from what you might be accustomed to as well. Using an accurate DMM, inspect the following items, and replace the ignition coil if it is found to be defective:
• Primary resistance
• Secondary resistance
Caution: If the resistance is extremely low, this indicates the presence of a short circuit.
(03/98 – 08/98)
In 1998, Subaru of Japan produced a widebody, 2-door, Impreza called the 22B STi. The 22B was used to commemorate both Subaru’s 40th anniversary as well as the 3rd consecutive manufacturer’s title for Subaru in the FIA World Rally Championship. On the release of the sales, all 399 sold out from 30 minutes to 48 hours, depending on the report.The cars had the starting VIN code of GC8E2SD. Another 25 were produced for export markets – see the 22B Type UK below.
The 22B had the EJ22 engine as opposed to the regular EJ20 engine. Note: internal Subaru material states the block comes from a V3 EJ20G NOT the EJ22G as most think. Also the intake manifold and heads were from the V4 EJ20K. This means the displacement was increased from 1994 cc to 2212 cc. The block is a closed-deck design. The heads (valves, valvetrain and such) were lifted from the STi Version 4 engine. It produce 350 PS (260 kW; 350 hp) at 6000 rpm and 363 N·m (267 ft·lbf, 37.0 kgf·m) of torque at a lower engine speed of 3200 rpm. The redline was lowered from 8000 rpm to 7000 rpm. The compression is an 8.0:1. The turbocharger is an IHI RHF 5HB (the internal company usage code is VF23).
This car was given a unique color of blue and had fender flared widebody taken from the Peter Stevens designed WRC car, thus widening the width by 80 mm (3.15 inches) for a total of 1,770 mm (69.7). During assembly, a WRX Type R chassis was taken off the line. The fenders were replaced with the 22B STi fenders. The car’s curb weight is 1,270 kg (2,800 lb). The suspension is provided by Bilstein. The brakes were standard 4-piston/2-piston brakes. However, the color is red and the Subaru name cast on the brake calipers and painted white.