Nissan 240sx Engine Swap Sr20det

So, you're thinking about an SR20DET swap into your Nissan 240SX, or maybe you've already taken the plunge and are running into some snags. It's a classic upgrade, adding a serious dose of power and performance to an already fantastic chassis. But like any engine swap, it's not always a walk in the park. Let's break down some common issues and solutions, helping you navigate the process and get that SR20DET screaming!

Common SR20DET Swap Issues in the 240SX

The SR20DET is a robust engine, but age and previous abuse can take their toll. Plus, the swap itself introduces new potential problem areas. Here are some of the frequent headaches we see:

Wiring Woes

This is probably the most common issue. Integrating the SR20DET wiring harness into the 240SX chassis harness can be tricky. Differences in pinouts, sensor placement, and even year-to-year variations in the SR20DET harness itself can cause headaches. You might experience:

Engine not starting: Often due to incorrect power supply or ignition signals.
Incorrect gauge readings: Tachometer, temperature, and fuel gauges can be inaccurate.
Check engine light (CEL): Indicating sensor issues or wiring errors.
Idle control problems: Erratic or high idle speeds.

Solution: Patience and a good wiring diagram are your best friends here.

Identify your harnesses: Determine the year and model of both your 240SX and your SR20DET engine/harness. This is crucial for finding the correct wiring diagrams.
Use a reputable wiring diagram: There are several online resources and forums dedicated to SR20DET swaps. Find a diagram specifically for your combination. Don't rely on generic or incomplete information.
Check grounds: Ensure all ground connections are clean and secure. Poor grounding can cause all sorts of electrical gremlins. This is often overlooked.
Consider a pre-made adapter harness: Companies like Wiring Specialties and Chase Bays offer pre-made harnesses that simplify the wiring process considerably. They're more expensive upfront, but can save you a lot of time and frustration. Expect to pay between $500-$1000 for a quality adapter harness.
Professional help: If you're not comfortable with electrical work, don't hesitate to take it to a professional. A qualified mechanic specializing in imports or engine swaps can diagnose and fix wiring issues efficiently. Labor costs will vary, but expect to pay $500-$1500 depending on the complexity.

Tools you'll need: Multimeter, wire strippers, crimpers, soldering iron (optional but recommended for secure connections), wiring diagram, heat shrink tubing, electrical tape.

Fuel System Inadequacies

The stock 240SX fuel system might not be up to the task of feeding a boosted SR20DET, especially if you're planning on increasing the boost. This can lead to:

Fuel starvation: Engine cutting out at high RPM or under boost.
Lean running conditions: Which can damage the engine.
Fuel pump failure: Overworked fuel pump giving out prematurely.

Solution: Upgrade your fuel system.

Fuel pump: A high-flow fuel pump is essential. A Walbro 255 LPH pump is a popular and reliable choice. Expect to pay around $100-$150.
Fuel injectors: The stock SR20DET injectors might be sufficient for a stock engine, but upgrading to larger injectors (e.g., 550cc or 740cc) is recommended for increased boost levels. Used injectors can be found but flow testing and cleaning are highly recommended. New injectors range from $300-$600 depending on size and brand.
Fuel pressure regulator: An adjustable fuel pressure regulator allows you to fine-tune fuel pressure and ensure a stable fuel supply. Aeromotive and Tomei are reputable brands. Expect to pay $150-$300.
Fuel lines: Consider upgrading to larger fuel lines to improve flow. Braided stainless steel lines are a good option.

Cooling System Issues

The SR20DET generates more heat than the stock 240SX engine, so the cooling system needs to be up to the task. Common problems include:

Overheating: Due to insufficient radiator capacity.
Coolant leaks: From old or damaged hoses.

Solution: Upgrade your cooling system.

Radiator: An aftermarket aluminum radiator with increased core thickness is a must. Mishimoto and Koyo are popular brands. Expect to pay $200-$500.
Radiator hoses: Replace all old radiator hoses with new silicone hoses. They're more durable and resistant to heat. A complete set will cost around $50-$150.
Thermostat: Consider a lower temperature thermostat to help keep the engine cooler.
Electric fans: Upgrading to high-performance electric fans can improve airflow, especially at low speeds.

Driveline Weakness

The stock 240SX transmission and differential might not be able to handle the increased power of the SR20DET, especially if you're running increased boost.

Transmission failure: Stripped gears or broken synchros.
Differential failure: Broken gears or axles.
Clutch slippage: Inability to hold the increased torque.

Solution: Beef up the driveline.

Clutch: A stronger clutch is essential. ACT, Exedy, and Competition Clutch offer a variety of options to suit different power levels and driving styles. Expect to pay $300-$800 depending on the clutch type.
Transmission: Consider upgrading to a stronger transmission, such as a Z32 transmission from a Nissan 300ZX. Alternatively, you can rebuild the stock transmission with upgraded gears and synchros. A used Z32 transmission may cost $500-$1000, while a rebuild can range from $500 - $2000 depending on parts and labor.
Differential: A limited-slip differential (LSD) can improve traction and handling. Kaaz, Cusco, and Tomei are popular brands. Expect to pay $800-$1500.
Axles: Upgraded axles can help prevent breakage under high power conditions.

Boost Leaks

Boost leaks can rob you of power and cause drivability problems.

Reduced power: Due to loss of boost pressure.
Erratic idle: Due to unmetered air entering the engine.
Poor fuel economy: Due to the engine trying to compensate for the lost boost.

Solution: Find and fix the leaks.

Pressure test: Pressure test the intake system to identify leaks. You can build your own pressure tester or purchase one online.
Inspect hoses: Check all vacuum hoses and boost hoses for cracks or damage. Replace any worn or damaged hoses.
Tighten clamps: Ensure all hose clamps are tight. Double-clamping is often recommended.
Check intercooler connections: Inspect the intercooler and its connections for leaks.

Idle Control Issues

Often related to wiring, incorrect adjustment, or a faulty idle air control valve (IACV).

High idle.
Low idle.
Surging Idle.
Stalling.

Solution: Troubleshoot and correct idle issues.

Vacuum Leaks: Check again for vacuum leaks as mentioned above. These can significantly affect idle.
IACV Function: Test the Idle Air Control Valve (IACV) resistance and voltage. Consult the FSM (Factory Service Manual) for testing procedures and acceptable ranges. A faulty IACV can cause a high or unstable idle. Replacing an IACV can cost between $100 and $300 for a new unit.
Throttle Position Sensor (TPS): Ensure the TPS is properly adjusted. An improperly adjusted TPS can send incorrect signals to the ECU, leading to idle problems. Use a multimeter and the FSM for correct adjustment.
ECU Issues: In rare cases, ECU problems can cause idle issues. If you've ruled out other possibilities, consider testing or replacing the ECU. A replacement ECU can range from $200 (used) to $800+ (new or aftermarket).
Consult a Specialist: If you've exhausted all other options, consult a mechanic specializing in SR20DET engines for a professional diagnosis.

The SR20DET swap is a rewarding upgrade that can transform your 240SX into a real performance machine. By addressing these common issues proactively, you can ensure a smooth and trouble-free swap. Remember to do your research, be patient, and don't be afraid to ask for help when you need it. Happy swapping!