Larrys Electric - Universal Tuned Port Injection harness Tuned Port Injection stand alone EFI wiring harness . This harness takes care of the headaches involved with installing Tuned port injection on most all SBC engines or swapping a TPI engine into your vehicle, and makes for a much easier installation. Our harnesses are tuned port injection harness | eBay Find great deals on eBay for tuned port injection harness. Shop with confidence. Skip to main content. eBay Logo: 87 Firebird Trans Am TPI engine wiring harness tuned port injection. Pre-Owned. $145. Buy It Now +$25 shipping. 88 vette Tuned Port Injection System With 2 ECM and Wiring Harness. Pre-Owned. $350.