Engine Reinstall & ECU Upgrade! Complete Wiring Harness Build for the Volvo 242 5 Cyl Turbo Swap

In today’s episode, we’re making a huge leap forward in the Volvo 242GT project. With the freshly rebuilt 5-cylinder engine waiting, it’s time to swap out the outdated Megasquirt MS3x ECU for a modern MaxxECU Race setup with a fully custom wiring harness. I’ll walk you through each step of this critical upgrade, from designing a custom wiring plan to building and routing a top-tier engine harness using high-quality components. Here’s what we’re tackling:

1. Planning the ECU Conversion: We'll dive into the wiring schematics, planning out each connection for the harness.
2. Building the Harness: Using Raychem shrink tubing, Kapton tape, and military-spec connectors, we’re creating a harness built to last. This isn’t just about connecting wires—it’s about reducing failure points and ensuring easy serviceability.
3. Installing the Engine and New Wiring: With everything in place, we’ll finally get this engine back where it belongs, making strides toward the first start.

This upgrade to MaxxECU has been a long time coming, and it’s a massive step forward for the car. Stick around to see the engine’s transformation and the meticulous process that goes into making a custom wiring harness that’s both functional and clean.

Hit Subscribe to stay up-to-date on the next steps, where we’ll be fabricating, tuning, and inching closer to getting this Volvo back on the road!

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Heatshrink I used:

Raychem DR-25 heatshrink - The go-to heatshrink used everywhere in the engine bay to protect wiring. Extremely flexible--I've not yet encountered anything else comparable.
Raychem ATUM heatshrink - Adhesive-lined heatshrink that comes in large sizes. Not very flexible, so I would use this sparingly only where you need adhesive.
Raychem SCL heatshrink - Adhesive-lined heatshrink that comes in smaller sizes and is ideal for sealing ends of Raychem DR-25 or connectors. Very rigid.

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