Reduced engine power is a mode which slow down your car and limits the acceleration as well. Problem of engine power reduce could be happened due to multiple reasons. As in car engine there are many sensor and actuator which is used to increase engine power. When anyone sensor or actuator did not function or stop functioning in proper manners than problem of reduced engine power can be seen.
Sensor & actuator that are used in engine:
Air mass sensor: air mass sensor measure the amount of air entering into combustion chamber. It can be found after the air filter body from where air enter into combustion chamber.
Manifold absolute pressure sensor: manifold absolute pressure sensor is use to monitor the pressure of air entering into combustion chamber. Most of time it is located on the intake manifold body from where air enter into combustion chamber.
Intake manifold runner: intake manifold runner is located at the intake manifold, from where air enter into combustion chamber. It open or close the butter fly valve of intake manifold according to the engine requirements.
Oxygen sensor or lambda sensor: there are two types of oxygen sensor one is installed at before catalytic converter and the other one is located after catalytic converter. Oxygen sensor is use to monitor the air fuel mixture presence in exhaust gas.
Exhaust gas recirculation sensor: exhaust gas recirculation sensor is located at the body of exhaust gas recirculation valve. It monitor the amount of exhaust gas entering into combustion chamber.
Exhaust gas recirculation valve: exhaust gas recirculation valve is use to take exhaust gas return into combustion chamber according to the engine requirement. It is located between exhaust gas and intake manifold to pass the exhaust gas from exhaust to combustion chamber.
Turbo charger actuator: turbocharger actuator is use to open or close the turbo charge fins. With the help of which turbo speed is maintain according to engine power requirements. It is located near the turbocharger and it is control by the nuematic or electronically.
Camshaft sensor: camshaft sensor is located according to the engine manufacture. But it is always present at the place from where it can measure the rotational speed of camshaft. Send this signal to engine control module, according to its signal engine control module control engine starting and fuel injection operation.
Crankshaft sensor: crank shaft sensor is present at the lower position of the engine. As crankshaft sensor of the engine is at lower position of the engine. It monitors the speed of crank shaft rotation and send this signal to engine control module. Engine control module use this signal to control the starting and fuel injection into combustion chamber.
Fuel rail pressure sensor: fuel rail pressure sensor is present at the end of fuel rail. From where fuel directly injected in to combustion chamber. Fuel rail pressure sensor is use to monitor the amount of fuel pressure in the fuel rail. Send this signal to engine control module according to which engine control module maintain the pressure of fuel from high pressure fuel pump.
Knock sensor: Knock sensor is present at the middle position of the engine block. It is a round circle shape sensor with hole in the middle of it. Knock sensor monitor the knocking of the cylinder knocking in the combustion chamber.
Catalytic converter sensor: it is located at the middle position of catalytic converter. It monitor if catalytic converter is block or not. If catalytic converter get block it send signal to engine control module. Because when catalytic converter get block, exhaust gas face trouble to pass throught it.
These are the different types of sensors and actuator’s which is used in engine to control the power, boost of engine. All these sensor and actuator work simultaneously according to the requirement of engine to create power.
How to trouble shoot reduced engine power:
Engine power reduce problem can be happen due to multiple reasons, like failure of sensor and actuators. If there is a problem of engine power reduce than you need to check all the above sensor and actuators. As this is not possible to check all the sensor and actuator one by one. In this situation you need to hook up scan tool to find out the actual faulty sensor or actuator.
For example, if fault code store in scan tool show problem regarding air entering into combustion chamber. Like if there is fault of air mass sensor, manifold absolute pressure sensor, exhaust gas pressure sensor etc. Than it means that there is some problem at air entering into combustion chamber. In this situation you need to check which fault code is store in control module in current position.
Like if air mass sensor fault code is store in engine control module in current position. Than it means that there is some problem at air mass sensor. Check air mass sensor reading while engine is start. If there is no reading is showing of about air mass sensor.
Than it means that sensor is not working. There could be some other problem also accept faulty air mass sensor. You need to check power supply at air mass sensor. Remove the connector of the sensor and check power supply, ground and reference voltage at sensor. If there is any thing missing than find damage wiring harness of the sensor or blown fuse of the sensor.
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But if power supply, ground and reference voltage is present in and still there is a fault code store in control module. Than it means that air mass sensor is faulty. Replace that faulty sensor so that fault code could be erase. Like this if there is any other fault code store in control module related to any other sensor. Which is related to problem of air entering into combustion chamber.
Other problem in this situation is that it could be possible that there is some leak at the intake manifold. From where extra amount of air enter into combustion chamber. Because when extra amount of air will enter into combustion chamber. Than air fuel mixture ratio will not proper. In result which engine may start missing, knocking due which also engine power reduce problem can be seen.
Also check actuator like intake manifold runner. Because if intake manifold runner actuator will not open intake manifold butter fly. Than air will mix proper in the engine combustion chamber. In result which engine may start missing, knocking, black smoke etc.
The second reason behind engine power reduced is low fuel pressure in the system:
This could be happen due to multiple reasons like faulty low pressure fuel pump, block fuel filter, high pressure fuel pump, fuel rail pressure sensor, failure of injector.
When scan tool show fault code of about low fuel pressure in fuel supply system. Like low fuel pressure in the system, fuel rail pressure sensor etc. In this situation you need to check fuel supply system from the start.
Start checking fuel supply system from low fuel pressure sensor. Check if low fuel pressure pump is working in or not. If it does not work than replace it, but it work than check the pressure of fuel from pump. Fuel pressure should be according to the engine requirements.
Than check fuel filter, if it block with dust particles of fuel. Than replace that fuel filter.
After this check fuel pressure after high pressure fuel pump. Most of the time this is main reason behind the low fuel pressure in the system. Check pressure of after if it match the required amount of pressure according to the engine control module. Than it is fine but if does not match the require pressure than replace that high pressure fuel pump.
If fuel pressure after after high pressure fuel pump is good. Than go to check the fuel rail pressure sensor if it faulty or not. If there is any damage wiring harness found than repair that wiring harness so that problem can be solve. Check power supply ground and signal wire on fuel rail pressure sensor. If all these is present at the sensor than it means that sensor is faulty. Replace faulty fuel rail pressure sensor. So that problem of low fuel pressure can be solve.
Mechanical fault due which problem of reduced engine power can be seen:
Compression leak: Compression leak is know as leak of compression from combustion chamber. It could be happen due to broken piston ring, bend head valve, leak from injector area. If there is no any electrical or mechanical fault at engine than check leak of compression. if found leak of compression close the leak from where compression get leak.
Low level of engine oil: engine control module monitor the pressure of engine oil circulating around combustion chamber. When engine control module monitor low pressure of oil from oil pressure sensor. Than it slow down the engine power to secure the engine from major damage in internal engine due to low pressure of oil.
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Block exhaust gas line: When exhaust gas line will block, than require amount of exhaust will not flow through exhaust line to combustion chamber. Exhaust gas sensor will monitor this and send signal to engine control module. When engine control module will recieve this signal, it will slow down the injection of fuel into combustion chamber. Due to which engine will loose it power and pickup.
Broken fins of turbo core: Turbocharger revolve at very high speed due to the pressure of exhaust gas. With the help of this pressure turbo charge inject air into combustion chamber in pressure. But when turbocharger core fins will broken and it will not be able to make the require pressure of air into combustion chamber. In result which engine power will reduce, it will not power up when accelerator is pressed.
Block intercooler: Intercoonler is connected with turbocharger, turbocharger take air from air filter. When turbocharger revolve at high pressure to make pressure, air get heat due to high speed of turbocharger fins. That is why a intercooler is connected with turbocharger and intake manifold. Hot air enter into intercooler, temperature of air change and than it enter into combustion chamber.
Solution of reduced engine power:
- Replace faulty sensor and actuator.
- Repair damage wiring harness of the sensor.
- Replace blown fuse of the sensor.
- Repair leak in the intake manifold from where extra amount of air enter into combustion chamber.
- Replace faulty low or high pressure fuel pump.
- Repair or replace leak fuel pipe line.
- Replace clogged fuel filter.
- Replace faulty actuator.