Category Archives: WRX

Subaru Turbocharger Explained Part 1

Subaru Turbocharger Explained:

Turbochargers are fairly simple in concept, but adapting the system to modern vehicles can be quite complex. This primer for those new to servicing turbos and review for veterans lays out the function and operation of turbocharging in Subaru vehicles.

Subaru Turbocharger: Starting with 2004 models, the WRX STi incorporates a water spray system to help cool the intercooler, thereby further cooling the intake air.
Subaru Turbocharger: Starting with 2004 models, the WRX STi incorporates a
water spray system to help cool the intercooler, thereby
further cooling the intake air.

The return of turbocharging in the 2002 Impreza WRX marked an absence of nearly a decade for Subaru vehicles. While the new generation has been around for half a decade, not everyone understands the function and operation of Subaru turbocharging systems.

Naturally, everyone knows these blowers are designed to get the maximum power out of engines by packing more air and fuel into the cylinders to get the biggest bang possible. Just how that is accomplished, however, may be a bit of a mystery to you. Here’s a primer on turbocharging and how it applies to Subaru vehicles.

Subaru Turbocharger Explained:

A Brief History of Turbochargers

Turbochargers were originally invented to increase the volume of air pushed into the cylinders of internal combustion engines, and, along with increased fuel, raise the level of energy produced by the combustion process

Historical references indicate that Swiss engineer Alfred J. Buchi adapted the turbines from steam engines to diesel engines as a method to improve air induction, and, therefore, smoother operation in internal combustion engines. In 1905, Buchi’s idea of powering the forced air induction by exhaust flow was granted a patent. Good idea or not, the fairly crude engines of the day could not sustain even or adequate boost pressures. Buchi worked another ten years before he could produce a working model of a turbocharged diesel engine. By that time, other companies had also produced turbocharging systems

The massive building boom of internal combustion engines to supply ships, trucks and airplanes for World War I saw technologies take a giant leap forward. The first turbocharged diesel engines for ships and locomotives appeared around 1920. Shortly thereafter, European car manufacturers began incorporating them into factory race cars and a few sporty luxury models.

The next milestone for turbocharging came with the military build-up for World War II, when turbo systems were fitted to fighter planes and bombers to allow them to fly at higher altitudes where the thinner air could be compacted into the engines to provide sufficient combustion. However, direct-driven superchargers quickly proved more reliable, efficient and more easily controlled, leaving turbochargers by the wayside.

It wasn’t until the mid-1950s when turbochargers started appearing on diesel trucks that modern turbos began to make a dent in the automotive market. Today, the vast majority of truck engines are turbodiesels.

When turbocharged vehicles began to dominate the international racing scene in the 1960s, car manufacturers began to use them in sporty models to appeal to performance-oriented drivers. By the 1980s, turbochargers for cars were a bona fide success, particularly in Subaru vehicles, due to improved metallurgy, intercooling and efficient boost controls.

The main components of a Subaru turbocharger system are a water-cooled turbocharger, an air-cooled intercooler, a wastegate control solenoid valve, sensors and a controller. Let’s review the individual components and the role they play in the system.

Subaru Cold Weather And Driveability

Subaru Cold Weather And Driveability:

The Winter season brings cold weather to many parts of the country, and with it the traditional driveability problems.

Subaru Cold Weather And Driveability: The Winter season brings cold weather to many parts of the country, and with it the traditional driveability problems.
Subaru Cold Weather And Driveability: The Winter season brings cold weather to many parts of the country, and with it the traditional driveability problems.

Before you push the panic button on Subaru cold weather and driveability problems, remember:

• No vehicle runs as well when it is cold as it does when it is at normal operating temperature.

• You have been operating the vehicle in more moderate temperatures and has gotten accustomed to the way it has been running. Now it is colder and things are not working the same.

• Some areas of the country may be using gasoline blended for warmer temperatures. These fuels normally do not atomize as well in cooler temperatures.

• Oxygenated and reformulated fuels that are in use in many parts of the country are normally harder to ignite in cold cylinders.

• Many drivers get their gas at one station because it may be close to home or work. Question them about this and if this is true, suggest they try a different brand of gas. It may take a couple tanks before any improvement is noticed. Different manufacturers blend their fuels differently.

• The 4EAT has a temperature sensor in the ATF and the Transmission Control Unit (TCU) will not allow an up-shift into 4th gear until the ATF has reached a specific temperature. This 4EAT design characteristic may be interpreted as a driveability problem by a driver who is not familiar with 4EAT operation.

There are many reasons for Subaru cold weather and driveability issues during cooler weather. Spending a few minutes with your Subaru and look over the points listed above should eliminate misconceptions about the Subaru cold weather performance and driveability characteristics of Subaru vehicles.

 

SI-Drive 2008+ STi Explained:

SI-Drive 2008+ STi Explained:

The 2008 Subaru Impreza WRX STI has a heritage of power and control. Previous models have been the foundations for countless racing victories and championships. The new WRX STI promises the same with it’s 305- horsepower, turbocharged, intercooled Boxer engine and a six-speed manual transmission.

SI-Drive: he new WRX STI promises the same with it's 305- horsepower, turbocharged, intercooled Boxer engine and a six-speed manual transmission.
SI-Drive: he new WRX STI promises the same with it’s 305- horsepower, turbocharged, intercooled Boxer engine and a six-speed manual transmission.

Power and control incorporate enchanced technology. As suggested by new switchgear on the dashboard and center console and my markings within the instrument cluster’s center-mounted tachometer, a driver has some things to learn before wringing out the most from the car.

Today’s electronics now allow the driver to tinker with engine response characteristics, the manner in which All-Wheel-Drive system fights for traction, and the degree to which braking and engine management help maintain vehicle stability. These capabilities are made possible by standard Vehicle Dynamics Control (VDC), Driver Controlled Center Differential (DCCD), and Subaru Intelligent Drive (SI-Drive).

Battery Charging Subaru:

Battery Charging Subaru:

Batteries low in voltage (below 11.6 volts) need to be specially charged. A battery at this voltage is heavily sulfated and needs either a very long, slow charge, or a very high initial charge voltage.

Battery Charging Subaru: Batteries low in voltage (below 11.6 volts) need to be specially charged. A battery at this voltage is heavily sulfated and needs either a very long, slow charge, or a very high initial charge voltage.
Battery Charging Subaru: Batteries low in voltage (below 11.6 volts) need to be specially charged. A battery at this voltage is heavily sulfated and needs either a very long, slow charge, or a very high initial charge voltage.

The battery should be left on the battery charger for at least two days. Since the acid in the battery will mostly be stratified, it needs sufficient overcharge to mix. Even after a two day charge, the battery still may only come to 60-80 percent of capacity and may need to be cycled to come to full charge. If possible, once the battery is fully charged by this method, it’s advisable to finish with a constant 1 amp for an additional 24 hours.

A battery that is below 11.6 volts can also be hydrated. This means there is lead sulfate in the separator that will form lead shorts once the battery charges. Because of these shorts, the battery may self discharge once the battery has been recharged.

Emission Testing State Subaru

 Emission Testing Subaru:

Emission testing of a Full-Time 4WD or all-wheel-drive vehicle must never be performed on a single two-wheel dynamometer, nor should a state I/M program inspector or its contractors install the FWD fuse in the engine compartment. Attempting to do so will result in uncontrolled vehicle movement and may cause an accident or injuries to persons nearby.

State Emission Testing Subaru: Emission testing of a Full-Time 4WD or all-wheel-drive vehicle must never be performed on a single two-wheel dynamometer
State Emission Testing Subaru: Emission testing of a Full-Time 4WD or all-wheel-drive vehicle must never be performed on a single two-wheel dynamometer.

Resultant vehicle damage due to improper testing is not covered under the SUBARU Limited Warranty and is the responsibility of the state I/M Program or its contractors or licensees.

The 1990 Clean Air Act Amendments require the Environmental Protection Agency (EPA) to implement programs to reduce air pollution from motor vehicles. Certain states are required to adopt either a “basic” or “enhanced” vehicle Inspection/Maintenance (l/M) Program, depending on the severity of their air pollution problem.

The ‘enhanced’ I/M emission testing simulates actual driving conditions on a dynamometer and permits more accurate measurement of tailpipe emissions than the ‘basic’ I/M test, which measures emissions only during engine operating conditions at idle and 2500 RPM. The ‘enhanced’ l/M test also includes a pressure check to identify evaporative emissions leaks in the fuel system.

Evaporative Emissions Testing Subaru

Evaporative Emissions Testing Subaru:

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.

Evaporative Emissions Testing Subaru: A major component of the Subaru OBD-II system is the system’s ability to monitor the evaporative emissions system.
Evaporative Emissions Testing Subaru: A major component of the Subaru OBD-II system is the system’s ability to monitor the evaporative emissions system.

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.

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.

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.