The 4.0L inline-six is one of the most reliable engines ever put in an off-road vehicle, and standalone ECU support is how you actually tune it.
The 1999 Jeep Wrangler 4.0L has a devoted following for its torque, durability, and tractability, but standalone ECU support has been genuinely limited. The Tuned By Shawn Boomslang PNP Wiring Harness for the Haltech Nexus connects directly to your factory harness without any permanent modifications, giving the Haltech Nexus full standalone engine control. No cutting, no splicing, fully reversible.
Advantages
- Torque delivery that's accurate and consistent at all speeds and loads
- Throttle response that's direct instead of over-dampened by aging factory mapping
- Fuel delivery that stays precise at altitude and in extreme temperatures
- Engine behavior calibrated to your actual modifications and use case
- A foundation for builds that need more than the factory ECU can offer
Features
- Plug-and-play fitment for 1999 Jeep Wrangler 4.0L, all transmission types
- Compatible with Haltech Nexus R3, R5, S2, and S3 ECUs
- No cutting or splicing of factory wiring
- OEM-quality connectors, USA-built by Boomslang Fabrication
- Fully reversible, factory harness preserved
- For competition and off-road use
The Details
Built specifically for this vehicle's connector layout with OEM-spec connectors and correct wire gauge throughout. Your factory harness stays completely untouched and the vehicle can return to stock at any time. In automatic transmission applications, the factory ECU remains in parallel for transmission control while the Haltech Nexus manages the engine.
Kit Includes
- 1x Boomslang PNP wiring harness for 1999 Jeep Wrangler 4.0L
- Haltech Nexus ECU sold separately
Fitment
1999 Jeep Wrangler 4.0L, All Transmission Types.