Category Archives: Ej20

2.5RS, AWD, Drivetrain, Ej20, forester, gc8, Impreza, JDM, Old School Subaru, STi, Subaru, UK, USDM, WRX

ABS 5.3 Antilock Brake System for Early Subaru Part 5:

ABS 5.3 Antilock Brake System for Early Subaru Part 5:

 

ABS 5.3 Antilock Brake System for Early Subaru Part 5: Beginning in approximately December of 1996, a new antilock braking system called ABS 5.3 was installed on Legacy vehicles equipped with ABS.
ABS 5.3 Antilock Brake System for Early Subaru Part 5:
Beginning in approximately December of 1996, a new antilock braking system called ABS 5.3 was installed on Legacy vehicles equipped with ABS.

 

Beginning in approximately December of 1996, a new antilock braking system called ABS 5.3 was installed on Legacy vehicles equipped with ABS. This system uses a Bosch hydraulic control unit and a Nippon electronic control unit. ABS 5.3 is a four channel control design which can independently control the front wheels and utilize select low control to control the rear wheels (a system which provides the same fluid pressure control for the two rear wheels if either wheel starts to lock up).

Although similar to other Subaru ABS systems, there have been enhancements to component operation and location. Diagnosis has also improved because of the ability of the 5.3 ABS system to communicate with the Select Monitor. The hydraulic control unit or HCU is located under the hood on the right side of the engine compartment. The size of the HCU has decreased by approximately a third from that of the ABS-2E system, used on previous model year vehicles.

The HCU controls brake fluid flow by utilizing eight solenoid valves. There is an inlet solenoid valve and an outlet solenoid valve for each wheel. Mechanically, the inlet solenoid valve is open during normal braking, and the outlet solenoid valve is closed. The HCU also contains a motor and pump assembly, which operates only while ABS is actively controlling the brake fluid flow–preventing a wheel lock.

Beginning in approximately December of 1996, a new antilock braking system called ABS 5.3 was installed on Legacy vehicles equipped with ABS.
ABS 5.3: Beginning in approximately December of 1996, a new antilock braking system called ABS 5.3 was installed on Legacy vehicles equipped with ABS.

Externally the HCU of the ABS 5.3 has a relay box attached. This allows troubleshooting of the valve and motor relay area to be kept separate from the troubleshooting of the solenoid valves and pump motor. There are four modes of operation for the ABS 5.3 system. They are normal, pressure-drop, pressure-hold and pressure-increase. When wheel lockup is sensed, Mode Two, Mode Three and Mode Four may be activated. They are described as follows:

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Ej20, ej20G, EJ257, exhaust, gc8, Intake, Intercooler, JDM, STi, Subaru, TMIC, Tuning, Turbo, UK, USDM, WRX

Wastegate and Boost Creep FAQ

Wastegate and Boost Creep FAQ

What is Boost Creep?

Boost creep is a situation where your wastegate port is not large enough to allow the exhaust gas to bypass the turbo. What happens is the exhaust gas will choke the wastegate port preventing further gas flow through the port. Then, the exhaust gas has to take the path of least resistance which is through the turbine of the turbo. This will spool the turbo ‘uncontrolled’ beyond your normal controlled max boost level.

Wastegate and Boost Creep FAQ: A stock Subaru turbo with the internal wastegate and stock actuator.
Wastegate and Boost Creep FAQ: A stock Subaru turbo.

The turbo will be spooling past wastegate spring rate pressure even though the wastegate is fully open thus it is uncontrolled. The best way to check for boost creep is to connect the turbo outlet port directly to the wastegate actuator port and go for a drive. In 4th gear you should normally get a stable boost level of about 0.5 BAR, if you have boost creep the boost will hit 0.5 BAR and will continue to rise with rpm until you either back off or hit overboost fuel cut.

Boost creep should only be present on a turbo that has very little restriction. For example a fully de-catted and high flow induction. It’s been found that the fast spooling IHI VF35 is very prone to boost creep. The cure is to remove the turbo and enlarge the wastegate port. Then, fit a stronger actuator 0.75 BAR the reason for this is because you have made the wastegate port larger. The effective size of the wastegate plate acting against the exhaust gas flow is larger which allows the exhaust gas excert more force on the wastegate plate.

This in effect weakens the effectiveness of the actuator. Before the increase in size of your wastegate port the actuator would open at 0.5 BAR, after the increase the actuator would open earlier at 0.3–0.4 BAR. After these changes are made to the turbo either a boost controller or a remap (to adjust solenoid duty cycle) should be sought to control the boost to a safe level.

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Ej20, ej20G, EJ25, EJ257, gc8, Intake, Intercooler, JDM, STi, Subaru, TMIC, Turbo, UK, USDM, WRX

Boost control systems on a Turbo Subaru:

Boost control system on a Turbo Subaru:

This guide covers most  boost related issues including a short introduction on how your boost systems work. This information is based on the Classic Impreza’s, but will cover the newer WRX/STi cars to a certain extent.

Safe boost levels:

When modding your car without mapping (full de-cat and high flow induction etc) you increase the efficiency of your turbo which could result in engine damage due to lean running at high rpm / max boost. To prevent damage always try and keep your boost level as close to standard as possible until your car is mapped for the increase in boost pressure.

TLDR: Don’t screw with your boost levels until you get the car tuned by someone who knows what they are doing. Otherwise you’ll probably end up with a blown up Subaru.

Boost Issues:

Is the boost control system connected correctly:

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2.5RS, AWD, Ej20, ej20G, forester, gc8, Impreza, JDM, Legacy, UK, WRX

ABS for Early Subaru Part 4:

ABS Brake System for Early Subaru Part 4:

Troubleshooting Process:

To troubleshoot ABS systems, it’s best to follow a step-by-step procedure like the one on the 1992 Legacy ABS-2E Service Manual Supplement. Enter the flow diagram with the symptom reported on the repair order.

ABS Brake System for Early Subaru Part 4: The Subaru Legacy RS was known for using this ABS System.
ABS Brake System for Early Subaru Part 4: The Subaru Legacy RS was known for using this ABS System.

The diagram calls that Trouble Occurs. The first step in the procedure is “Basic Checks.” This calls for a visual inspection to look for obvious problems and includes the following items:

• improper battery voltage
• low brake fluid level
• brake fluid leaks
• brake drag
• condition of the brake pads and rotors
• size, type, and condition of the tires (Check the tires to confirm that they are the correct tires for the vehicle, that they are in good condition, and that they are inflated to the correct pressure).

If you find something wrong at this stage, correct it and see whether it eliminates the reported symptom. If not, continue to Step 3. Step 3 is Self-diagnosis. At this time, put the ECU into self-diagnostic mode, and monitor the ABS warning lamp for trouble codes.

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AWD, Ej20, ej20G, forester, gc8, Impreza, Legacy, Subaru, UK, USDM, wrc, WRX

Antilock Brake System for Early Subaru Part 3:

Antilock Brake System for Early Subaru Part 3:

Damping Oscillations:

An additional benefit of this arrangement is that the mechanical valve damps out some of the unwanted oscillation in the brake pedal as the ABS pump runs. Because of this, the F valve used on the ABS-2SL system is no longer needed and has been eliminated from the circuit.

Antilock Brake System for Early Subaru Part 3: The Legacy RS rally car benefited greatly from having a superior ABS unit.
Antilock Brake System for Early Subaru Part 3: The Legacy RS rally car benefited greatly from having a superior ABS unit.

 

ABS Operating Modes:

To illustrate the four operating modes of this ABS system, we’ll assume that the ECU is operating only the solenoid for the right rear brake circuit. Recall that this circuit also affects the left rear brake circuit through the mechanical valve.

Normal Braking:

• Driver depressing pedal

• ECU passive (monitoring)

• Zero current in solenoid valves

• Pump off

• Plunger piston full right, pressure port open

• Master cylinder pressure supplied to all wheel cylinders

Pressure-Reduce:

• Pump pressure raising pedal

• ECU controlling solenoid valves and pump

• Full current in the right rear solenoid valve

• Pump running

• Plunger piston moves left, closes pressure port; system balances the two rear wheel cylinders.

Pressure-Hold:

• Pedal firm

• ECU controlling solenoid valves and pump

• Half current in the right rear solenoid valve

• Pump Off

• Pressure port closed

• Plunger piston is stationary, maintains reduced pressure in the right and left rear wheel circuits.

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Ej20, EJ25, EJ257, STi, Subaru, USDM, WRX

Alternator Replacement Subaru WRX/STi:

Alternator Replacement Subaru WRX/STi:

This is a step by step guide in replacing a alternator on a EJ series engine on a 02-07 Subaru WRX/STi.

Alternator Replacement Subaru WRX/STi: The Alternator cover needs to be removed.
Alternator Replacement Subaru WRX/STi: The Alternator cover needs to be removed.

1.) Open up the hood and disconnect the battery. Note: This is important. If you fail to disconnect the battery, you will be grounding out your tools and making all sort of popping noises and sparks. It can destroy your electrical system. So ensure that your battery is disconnected. It’s best to just remove the battery itself from the car.

2.) Take the plastic cover off that sits over the belts on the front of the EJ series engine. There are a couple of 10mm bolts. The bolts are pretty easy to get off. On your WRX and STi there is also some clips that will come off. The best way to get them off the cover is to use a needle nose pliers on the bottom side to undo the clips.

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2.5RS, AWD, Drivetrain, Ej20, forester, gc8, Impreza, JDM, Legacy, Subaru, Suspension, UK, USDM

Antilock Brake System For Early Subaru Part 2:

Antilock Brake System for Early Subarus:

ABS Service And Brake Bleeding Procedures:

Antilock Brake System for Early Subarus: The first Subaru rally car the Legacy RS relied upon the bousch/nippon ABS units to perform on the WRC circuit.
Antilock Brake System for Early Subarus: The first Subaru rally car the Legacy RS relied upon the bousch/nippon ABS units to perform on the WRC circuit.

Always check the fluid level of the master cylinder and bleed the wheel cylinders following the procedure listed in the service manual. When the HCU has been removed and/or replaced, the fluid must be drained. Replace the cone screws with bleed screws and attach a hose to drain fluid to a container.

Antilock: ABS Service And Brake Bleeding Procedures: A early Subaru Nippon ABS unit ECU.
Antilock: ABS Service And Brake Bleeding Procedures: A early Subaru Nippon ABS unit ECU.

Use extreme care when performing this procedure to prevent damage to the internal components of the HCU. Do not apply AV signal for more than 5 seconds for each application. If no AV signal is received, it is not necessary to close bleed screw between brake pedal applications.

Antilock Brake System Notes and Cautions:

The ECU on early Subaru ABS systems can only display one trouble code–the lowest numbered code. Correct the fault indicated by the trouble code and recheck ECU for another code. Repeat the self-diagnostic procedure listed above, and the next highest code will be displayed. Refer to the appropriate model year service manual for the trouble codes and corrective actions. While the ABS ECU is in the fault mode, the ABS will go to fail-safe and remain passive under all braking conditions. The brake system will function as a conventional power-assisted system without ABS.

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2.5RS, AWD, Drivetrain, Ej20, EJ25, forester, gc8, Impreza, STi, Subaru, Transmission, UK, USDM

Maintenance:Subaru Periodic Maintenance Part 3:

Maintenance: Subaru Periodic Vehicle Maintenance Services:

Brake Fluid:

Many late model Subaru vehicles are equipped with ABS braking systems. The added complexity of these systems provides an additional incentive for following the recommended brake fluid replacement interval of 30 months or 30,000 miles. Brake fluid accumulates water and other contaminants over time. These contaminants can attack the internal parts of the brake system, compromising its performance and possibly causing brake failure.

Maintenance: Subaru Periodic Vehicle Maintenance Services: Make sure to replace brake fluid at least every 30 months of 30,000 miles. At least once a year if the Subaru sees heavy track use.
Maintenance: Subaru Periodic Vehicle Maintenance Services: Make sure to replace brake fluid at least every 30 months of 30,000 miles. At least once a year if the Subaru sees heavy track use.

The brake master cylinder has a semi-transparent reservoir, making it possible to check the fluid level without removing the reservoir cover. This minimizes the exposure to outside air and limits the amount of moisture that can reach the brake fluid. The fluid level will drop as the brake shoes and pads wear, but the reservoir is large enough to compensate for these changes. If the fluid level is very low, it’s a sure sign the brake pads or shoes are nearly worn out, or there is a leak in the brake system.

Note: When the brake fluid level in the reservoir tank is lower than the specified limit, the brake fluid warning light in the combination meter will come on.

Subaru warns against mixing brake fluids from different manufacturers. Doing so may degrade the quality of the fluid. Only DOT 3 or 4 brake fluid should be used in any Subaru vehicle preferably Subaru brake fluid if you are not going to do a track day build. Consult the service manual for vehicle specific brake bleeding procedures.

Subaru OEM Brake Fluid:

Subaru SOA868V9220 Brake Fluid – 1 Pint

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