Modified Car? Here’s Why You Should Be Keeping Records

So you’ve poured your time, money, blood, and busted knuckles into your modified car. Whether it’s a weekend warrior, a street sleeper, or a fully engineered beast — if it’s modified, you need to be keeping records.

Not for the tax man. Not even for resale (though it helps).
For you.

🔧 Why Keep Records?

1. Troubleshooting becomes 10x easier.
When your car won't start, having to guess what injectors, ECU, or sensors are installed is the fast track to wasted time and money. Document what parts were installed, what most recent maps were loaded and what wiring was modified.

2. Future upgrades and tuning.
Want to go from NA to turbo? Upgrade injectors or fuel system. Knowing your baseline specs, wiring changes, and part numbers saves hours plan the next move. It is your blood you know the first change will not be the last.

3. Compliance and engineering sign-off.
Modified vehicles often need engineering reports or mod plates. Engine swaps, transmission swaps and brake upgrades, to name a few— everything is easier to verify and explain with clear documentation and images.

4. Insurance.
Some insurers cover modified cars — but only if you can prove what's been done. Records, receipts, and photos can mean the difference between a payout or a painful denial.

📁 What Should You Be Recording?

Here’s a checklist to help future-you:

⚙️ Hardware

• ECU brand, model, and serial number (serial number especially if it get stolen)
• PDM / Fuse & Relay relocation setups — brand, model, and exact mounting location
• Wideband controller, CAN hubs, dash displays — model and where they’re installed
• Part numbers for key sensors (MAP, IAT, coolant, oil pressure/temp, flex fuel, etc.)
• Injector brand and flow rate (cc/min or lbs/hr)
• Turbo & wastegate specs
• Fuel pump & regulator models
• Wheels, tyres, brakes, suspension specs
• Can drawing or simple MUD maps of custom parts.

📍 Mounting Locations

• Where the ECU is mounted — under dash, behind kick panel, under seat, etc.
• PDM / fuse blocks — front inner guard, cabin, centre console?
• Battery relocations
• Sensor mounting — e.g. IAT in plenum vs intake, flex fuel on return line

Photos are gold here. Take wide and close-up shots when you install things.

🔌 Wiring & Electronics

• Custom wiring diagrams — even a hand-drawn sketch is better than nothing
• Pinouts for custom looms
• CANbus layout or communication map
• Notes on shared grounds, switched power sources, fuse sizes
• Relay and fuse box locations and their assignments
• Splice points or breakout harness info

If you’re using a Link, Haltech, or MoTeC ECU — export a copy of your config/tune file and store it with your docs. Include firmware version and any notes from your tuner.

🧾 Documentation

• Photos of each stage of the build
• Receipts for major parts
• Logbooks, tune revision history, dyno sheets
• Engineering/mod plate approvals if applicable

🏁 Final Thoughts

Building a modified car is part science, part art — and part detective story when something goes wrong. Keeping detailed records isn’t just smart; it’s essential.

You’ll thank yourself when:

• A sensor fails and you need to know the thread pitch or pinout
• Your tuner asks what firmware the ECU has
• You sell the car and want top dollar
• You need to prove your setup for insurance or compliance

Build it right and document it.

#ModifiedCarTips #ECUSetup #KeepRecords #WiringDiagramsMatter #BuiltNotGuessed