EXHAUST MANIFOLD W/ TURBOCHARGER SYSTEM DESCRIPTION
This section should be used as a guide for troubleshooting when the turbocharger sub-assembly is suspected as the cause of a problem.
OUTLINE OF TURBOCHARGER SUB-ASSEMBLY FAILURE
State of Turbocharger Sub-assembly Failure Repair
It is well known that turbocharger sub-assembly malfunctions cause many symptoms as shown below. However, the mechanisms resulting in these symptoms that indicate turbocharger sub-assembly malfunctions are not well understood. As a result, many unnecessary turbocharger sub-assembly replacements and other repairs are performed due to lack of knowledge about the turbocharger sub-assembly and turbocharger sub-assembly failure. Therefore, knowing the facts regarding turbocharger sub-assembly malfunctions is useful for making effective repairs and saving time.
Turbocharger Failure Classification
Symptom
Symptom Description
See page
Noise
Whistling noise
Continuous high pitch noise proportional to engine speed
Whining noise
Relatively low pitch noise compared to whistling noise
Oil leak
External oil leak
Oil leak on surface of turbocharger sub-assembly visible from outside of turbocharger sub-assembly
Internal oil leak
Oil leak from inside of bearing housing to inside of either compressor housing or turbine housing through seal ring
White smoke
Oil smoke
Oil smoke is emitted from exhaust pipe
Unburned fuel smoke
Unburned fuel smoke is emitted from exhaust pipe
Black smoke
Black smoke is emitted from exhaust pipe
Lack of power or hesitation
Vehicle does not reach target speed
Poor acceleration
Shock during acceleration
MIL turns on
DTC P1251
Overboost Condition (too High)
DTC P0299
Underboost
DTC P0046
Turbocharger Actuator Movement is Irregular
DTC P0047
DC Motor Malfunction
DTC P0048
DTC P2564
Nozzle Vane Position Sensor Malfunction
DTC P2565
Tip:This table shows only typical problems related to the turbocharger sub-assembly.
NOISE
Table 1. Description Probable Cause
Probable Faulty Component
Turbine shaft imbalance
Turbocharger sub-assembly
Leakage from intake line
Intake line
Gear noise
(Mistaken for turbocharger sub-assembly noise)
Transmission gear
Vacuum pump gear
Tip:It is easy to confirm whether the turbocharger sub-assembly is the cause of the noise or not, and confirming this before inspecting the turbocharger sub-assembly or removing it from the engine is an effective way to reduce troubleshooting time.
Connect the GTS to the DLC3.
Start the engine.
Warm up the engine.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VN Turbo Open.
Powertrain > Engine and ECT > Active Test
Tester Display
Activate the VN Turbo Open
Perform the Active Test and rev the engine up several times.
Check whether the noise is reduced or not compared with the noise when the Active Test is not performed.
Result
Cause of Noise
The noise disappeared or is reduced
Turbocharger sub-assembly
The noise does not change
Not turbocharger sub-assembly (other parts)
Tip:For details regarding the troubleshooting of noise, refer to Turbocharger Noise.
OIL LEAK AND WHITE SMOKE
Table 2. Description Oil Leak Type
Description
Main Trouble Area
Internal oil leak
(White smoke)
Oil leak from bearing housing to either compressor housing (intake side) or turbine housing (exhaust side) through seal rings
This type of oil leak is not visible from outside of turbocharger sub-assembly
If oil leak occurs from turbine side seal, large amount of white smoke is emitted from exhaust pipe
Compressor side seal ring
Turbine side seal ring
Clogging of oil drain
Shaft breakage
Shaft or bearing seizure
Compressor impeller damage
External oil leak
Oil leak from inside of turbocharger sub-assembly to outside of turbocharger sub-assembly
Includes oil leaks visible from outside of turbocharger sub-assembly
FIPG sealing part
Oil pipe flange
Hose connection of intake pipe
*1
Turbine Housing
*2
Seal Ring
*3
Turbine Wheel
*4
Oil Drain (Outlet)
*5
Bearing Housing
*6
Turbine Shaft
*7
Compressor Impeller
*8
Compressor Housing
*9
FIPG Sealing Part
*10
Compressor Inlet
*a
Internal oil leak to turbine housing
*b
Internal oil leak to compressor housing
Tip:When there is an internal oil leak, white smoke is emitted from the exhaust pipe and oil is consumed excessively. However, the cause of white smoke or excessive oil consumption can vary. Therefore, do not assume that the turbocharger sub-assembly is the cause of the failure when there is white smoke emission or excessive oil consumption.
When there is an external oil leak, the sources of the oil leak are limited to the points listed in the table above. If oil leaks from a FIPG sealing part, replace the turbocharger sub-assembly. If oil leaks from an oil pipe flange or a hose connection, do not replace the turbocharger sub-assembly, but check and repair the flange or hose.
For details regarding the troubleshooting of oil leaks and white smoke, refer to Turbocharger Oil Leak and White Smoke.
BLACK SMOKE
Malfunctions are classified into 2 types as shown below.
Table 3. Description Malfunction
Main Fault
Intake air volume shortage
Insufficient mass air flow due to, for example, excessively low boost pressure, which results in fuel injection volume being relatively excessive with respect to mass air flow
Excessive injection volume
Excessive injection volume or incorrect injection timing due to fuel system trouble
Main Components Related to Black Smoke
Probable Faulty Component
Main Fault
Turbocharger sub-assembly
Abnormally low boost pressure
Intake system
Leakage between turbocharger sub-assembly and intake manifold
Fuel system
Excessive fuel injection volume
Incorrect fuel injection timing
EGR valve
Stuck or does not close completely
Diesel throttle
Stuck or does not move smoothly
Tip:The components listed above are only the main ones. Not all the components potentially related to black smoke are listed. For details regarding the troubleshooting of black smoke, refer to Black Smoke Emitted.
Relation between Turbocharger Sub-assembly and Black Smoke
If the boost pressure is lower than normal due to a turbocharger sub-assembly failure, black smoke may occur due to a lack of mass air flow. However, abnormally low boost pressure can be caused by the failure of various components, such as intake lines, the EGR valve, etc. Therefore, do not assume that the turbocharger sub-assembly is the sole cause of abnormally low boost pressure, but check all the components possibly related to abnormally low boost pressure. Components related to abnormal boost pressure are shown in a chart (Click here). For simple and effective troubleshooting, refer to the chart before starting troubleshooting.
LACK OF POWER AND HESITATION
Malfunctions are classified into 2 types as shown below.
Table 4. Description Malfunction
Main Fault
Intake air volume shortage
Insufficient mass air flow due to, for example, excessively low boost pressure, which results in fuel injection volume being restricted
Abnormal injection volume
Abnormal injection volume or timing due to fuel system trouble
Main Components Related to Lack of Power and Hesitation
Probable Faulty Component
Main Fault
Turbocharger sub-assembly
Abnormal boost pressure
VN does not move smoothly
Intake system
Leakage between turbocharger sub-assembly and intake manifold
Clogging or blockage of intake line
Fuel system
Abnormal injection volume
Incorrect fuel injection timing
EGR valve
Stuck or does not close completely
Diesel throttle
Stuck or does not move smoothly
Exhaust system
Clogging of exhaust line
Tip:The components listed above are only the main ones. Not all the components potentially related to lack of power and hesitation are listed. For details regarding the troubleshooting of lack of power and hesitation, refer to Lack of Power or Hesitation.
If an obvious malfunction (lack of power) can not be reproduced, perform a test drive of another vehicle, which is the same model and has the same engine, and compare the engine operation and performance. If a great difference is not present in engine performance, explain to the customer that abnormal operation was not noted.
Relation between Turbocharger Sub-assembly and Abnormal Boost Pressure
If the boost pressure is lower than normal due to a turbocharger sub-assembly failure, lack of power could occur due to an intake air volume shortage. However, abnormal boost pressure can be caused by the failure of various components, such as intake lines, the EGR valve, etc. Therefore, do not assume that the turbocharger sub-assembly is the sole cause of abnormal boost pressure, but check all the components possibly related to abnormal boost pressure. Components related to abnormal boost pressure are shown in a chart (Click here). For simple and effective troubleshooting, refer to the chart before starting troubleshooting.
MIL TURNS ON
If a DTC related to a turbocharger sub-assembly malfunction is stored, refer to the troubleshooting section for each DTC.
BRIEF OUTLINE OF TURBOCHARGER SUB-ASSEMBLY OPERATION AND CONSTRUCTION
A turbocharger sub-assembly is a component used to supply a larger air volume to the cylinders by recovering exhaust gas energy using a turbine coaxially connected to a compressor.
Principle of Turbocharging
Boost pressure is proportional to turbocharger sub-assembly speed, because the intake air is accelerated by centrifugal force generated by the rotation of the compressor and the increased kinetic energy, the velocity of the intake air, is converted to pressure energy by the diffuser located around the outlet of the compressor impeller. The compressor is driven by the turbine connected coaxially to the turbine shaft. The turbine is driven by exhaust gas energy. Therefore, when the turbocharger sub-assembly begins boosting the intake air, a larger air volume is supplied to the cylinders and more fuel can be injected. As a result, more exhaust energy is available and the turbocharger sub-assembly boost increases.
*1
Compressor
*2
Turbine
*3
Air Cleaner
*4
Exhaust Manifold
*5
Intercooler
*6
Intake Manifold
*7
Diffuser
-
-
*a
See HINT below
*b
Intake Air Flow
Tip:*a: If sufficient exhaust gas energy is not available, the turbocharger sub-assembly cannot generate the required boost pressure even when the turbocharger sub-assembly does not have a malfunction.
Considering the fact that the turbocharger sub-assembly is driven by exhaust gas energy, if sufficient exhaust gas is not available due to abnormal injection volume, etc., the required boost pressure will not be available even when the turbocharger sub-assembly does not have a malfunction. Therefore, when boost pressure is abnormally low, checking all the related components using the correct troubleshooting procedure is necessary for simple and effective repair.
Boost Pressure Control
The amount of energy the turbine can obtain from the exhaust gas is proportional to the expansion ratio, which is defined as the ratio of the turbine inlet exhaust gas pressure to the pressure at the turbine outlet. To control boost pressure, a Variable Nozzle (VN) is used just upstream of the turbine wheel inlet, and controls the expansion ratio. If the VN is closed, the gap between neighboring vanes is narrowed and the turbine inlet exhaust gas pressure, and correspondingly the expansion ratio, increases. Therefore, when the VN is closed, the turbine receives more energy, and the turbine speed and boost pressure increase. On the other hand, if the VN is opened, the turbine inlet exhaust gas pressure decreases and the turbine speed and boost pressure decrease.
*1
VN (Variable Nozzle)
*2
Turbine Wheel
*3
Narrow Gap
*4
Wide Gap
*a
VN Closed
*b
VN Open
*c
Exhaust Gas Flow
-
-
Tip:If the VN becomes stuck open, the required boost pressure will not be not available. If the VN becomes stuck closed, overboost will occur.
Mechanical Construction of Turbocharger Sub-assembly
*1
DC Motor
*2
VN Actuating Rod
*3
VN (Variable Nozzle)
*4
Bearing Housing
*5
Turbine Wheel
*6
Turbine Housing
*7
Turbine Shaft
*8
Turbine Side Seal Ring
*9
Radial Bearing
*10
Thrust Bearing
*11
Compressor Side Seal Ring
*12
Compressor Impeller
*13
Compressor Housing
*14
Oil Drain
*a
See HINT below
*b
See HINT below
*c
See HINT below
-
-
Exhaust Gas Flow
Intake Air Flow
Tip:*a: The clearances of the radial bearing and thrust bearing are on the order of 100 μm, and for the accurate measurement of these clearances, an accurate process and accurate tools are essential.
*b: A certain amount of oil mist from PCV gas is contained in the intake air. Therefore, a certain amount of oil at the inlet of the compressor is normal and is not due to an oil leak.
*c: The seal rings are C-shaped rings, like piston rings, and have a gap. Therefore, complete sealing is impossible by the seal rings alone. The oil is sealed in with the aid of the boost pressure in the compressor housing and the exhaust gas pressure in the turbine housing. These pressures prevent oil from exiting the bearing housing through the gap of the seal rings. Therefore, if the turbine shaft is inclined from horizontal, oil may flow out through the gap of the seal ring. This should not be interpreted as an oil leak due to seal ring failure.