The Nissan SR20DET engine is a high-performance, turbocharged 4-cylinder found in numerous Japanese and European market vehicles. Since the engine was never offered in a vehicle sold in the American market, many enthusiasts purchase preowned SR20DET engines to swap into other vehicles, such as the Nissan 240SX. If yours features a custom SR20DET engine, it's important to perform all scheduled maintenance, which can be found in the Nissan Silvia owner's manual. However, if you are experiencing performance issues from your engine, there are numerous troubleshooting and tune-up procedures you can perform.
Locate the spark plug wires, installed into the top of the engine valve cover. Disconnect the wires by hand. Use a spark plug socket and socket wrench to remove the spark plugs, and check the bottom of each plug. Carbon buildup on the plug terminal indicates a faulty spark plug or ignition system. Alternatively, if all four plugs are carbon fouled, this indicates an overly rich air-to-fuel mixture. If there is oil buildup on the terminal, this generally indicates a damaged internal seal, such as a piston ring. If you discover oil on the plug, use a compression tester device to check the compression of the oil-fouled cylinder. If compression is beneath 128 psi, the cylinder ring must be replaced.
Inspect the air intake filter, located on the right side of the engine bay. If your SR20DET is using the stock intake, unfasten the metal hinge clamps that secure the airbox lid, then lift the lid free to access the air filter. A dirty or damaged air filter will hinder airflow, and thus cause a decrease in engine performance. Replace your worn filter with a performance, high-flow air filter. This will improve airflow compared to a stock or worn unit, which increases engine horsepower and helps ensure reliability.
Inspect the various rubber vacuum lines connected throughout the turbocharger and intercooler system. These lines are used to equalize the turbocharger air pressure. Since the lines are made of rubber, they are prone to cracking over time due to the extreme heat produced in the engine bay. A damaged line will allow turbo boost pressure to leak out of the system, which leads to diminished engine performance. Replace any damaged vacuum lines, and ensure every line is securely connected.
Inspect the intercooler system for damage or loose connections. This is the piping that's routed in front of the engine, connecting the turbocharger outlet to the engine throttle body. Throughout the intercooler system are numerous rubber pipe adapters, which are prone to stretching due to turbocharger heat and pressure. A damaged or insecure pipe adapter allows for a boost pressure leak, which diminishes turbocharger and engine performance. An extensive boost leak may even cause premature engine failure. Ensure that all intercooler pipe adapters are tightly secure and free of cracks, and replace any damaged adapters.
Drive to a safe and legal roadway on which to accelerate your SR20DET to the engine redline at 7,000 rpm. Accelerate the engine at full throttle while listening carefully to the noise of the turbocharger. An excessive turbo whining noise indicates worn turbocharger bearings. A metallic grinding noise indicates excessive shaft play, which allows the turbine to grind against the turbo housing. In either case, have your turbocharger rebuilt or replaced as soon as possible to ensure continued performance.
Look for excessive smoke produced from the exhaust system when the engine is accelerated. Blueish smoke indicates that oil is being combusted in the cylinders, likely caused by a damaged piston seal or other internal gasket. Alternatively, since the SR20DET features an oil-cooled turbocharger, damaged turbo internals may allow oil to enter the intake and combustion system. White exhaust smoke indicates that coolant is being combusted, commonly due to a damaged head gasket. Worn seals and gaskets should be replaced immediately to avoid total engine failure.
