The ECU is only one part of the job. The harness choice, wideband placement, air temp sensor, ignition setup, flex fuel goals, and year-specific wiring details matter just as much as the part number on the ECU.
Race use note
Haltech products and standalone ECU conversions should be treated as race/off-road use planning unless your local rules say otherwise.
Suggested Paths By Year Group
91-93
Early first-gen cars
Start with the correct early-car harness direction. Good fit for a clean Elite 2500 or Nexus S3 style standalone plan, wideband control, IAT conversion, and coil-on-plug if the ignition system is being modernized.
Match the adapter to the engine harness, not just the model year on the title.
Confirm crank/cam signal strategy before wiring.
Plan wideband extension length before mounting the controller.
94-95
Transition years
These cars need extra attention because drivetrain, ECU, and harness combinations are often swapped. The right answer depends on what is actually in the car now.
Verify ECU plugs and engine harness before ordering.
Confirm MAF delete, speed density, and IAT location.
Add flex fuel and boost control only after the core install path is clear.
96-97
OBD2-era planning
Later cars usually benefit from a cleaner plan around gauges, diagnostics, and how much factory behavior you want to keep. This is where accessory wiring notes become important.
Document factory sensor retention before the install.
Choose CAN gauge or dash options early.
Plan boost, knock, and wideband channels around the final tune goal.
98-99
Late second-gen cars
These are lower-volume cars, so assume nothing. Verify the harness, ECU plugs, emissions equipment, and any prior swaps before buying the adapter or universal wiring path.
Send photos of ECU plugs and engine bay wiring when in doubt.
Universal wiring may be smarter for heavily modified builds.
Bundle sensors and connectors so the install does not stall mid-job.
