For car enthusiasts seeking to boost their vehicle’s performance, engine swaps can be a thrilling, albeit challenging, endeavor. This article details a comprehensive 4G93 engine swap project into a 1999 Mitsubishi Lancer GLXI, offering insights into the process, hurdles encountered, and key takeaways for anyone considering a similar upgrade. The focus here is not just on the mechanical aspects but also on the electronic integration, particularly concerning the 4g93 Obd2 system and ensuring seamless functionality.
The Motivation Behind the Swap
The journey began with a desire for more power. The original 1.5-liter 4G15 engine, while reliable, lacked the punch that the owner craved. After years of dedicated maintenance and self-servicing, the engine’s increasing oil consumption and declining performance signaled it was time for a significant upgrade. A rebuild was considered, but the allure of enhanced power led to the decision to swap in a more potent engine – the 4G93.
Donor Engine and Vehicle Details
The chosen donor was a 2002 Mitsubishi Lancer MR Coupe, equipped with a 1.8-liter 4G93 SOHC 16V MPI engine. This engine offered a significant step up in performance and, importantly, featured an OBD2 (On-Board Diagnostics II) system, which is crucial for modern engine management and diagnostics.
Here’s a comparative breakdown of the vehicles:
- My Car: 1999 Lancer GLXI 1.5l Coupe 2D Manual
- Original Engine: 4G15 SOHC 12V MPI, Distributor Driven, Five Bolt
- Donor Car: 2002 Lancer MR 1.8l Coupe 2D Automatic
- Rebuilt Engine: 4G93 SOHC 16V MPI, Coil Pack Driven, Seven Bolt
Parts and Rebuild Highlights
The 4G93 engine sourced from the donor car underwent a meticulous rebuild, ensuring reliability and optimal performance. Key components used in the rebuild included:
- JUN Valve Stem Seals
- Hastings Piston Rings (81.0mm)
- JUN Crankshaft & Conrod Bearings
- NOK Crankshaft & Camshaft Seals
- Valve Cover Seal
- NGK Iridium Plugs
- Gates Timing Belt Kit
- Gates Alternator & AC Steering Pump Belts
- Exedy Heavy Duty Clutch Kit
- 7 Bolt Manual Flywheel From The US (215mm)
- Ryco Fuel & Oil Filters
- FeelPro MLS Head Gasket
Alt Text: Assortment of new engine components including gaskets, seals, and bearings prepared for the 4G93 engine rebuild.
Beyond just replacing parts, significant extra work was performed to enhance the engine’s condition and performance:
- Precision Measurement: Clearances were meticulously measured using the PlastiGauge method on all crankshaft and piston mating surfaces to ensure proper tolerances.
- Surface Refinement: All mating surfaces were resurfaced to eliminate imperfections and scratches from old bearings, ensuring optimal sealing and component longevity.
- Cylinder Head and Block Work: The cylinder head and engine block mating surfaces were resurfaced and checked for warpage, correcting any deviations to guarantee a perfect seal with the head gasket.
- Porting and Polishing: Intake and exhaust ports on the head were carefully grinded and ported to improve airflow, and intake and exhaust manifolds were gasket-matched to the head for seamless transitions.
- Valve Refacing: Valves were grinded and mated into their seats using Permatex valve grinding compound, followed by manual leak testing to ensure perfect valve sealing.
- Thorough Cleaning: Every engine component underwent a thorough degreasing and cleaning process. The engine block, head, and pistons were acid bathed and degreased. The engine block was repainted, along with the valve cover and sump, to give a fresh and clean look.
- Assembly Lubrication: Mitsubishi-specified sealants and STA assembly lube were used during reassembly to ensure proper sealing and reduce friction during initial engine startup.
- Gearbox Servicing: The gearbox was cleaned internally and externally, synchronizers were inspected, and the unit was resealed after checking for any metal shavings indicative of wear.
- Engine Bay Preparation: The engine bay was thoroughly cleaned before the new engine installation.
- Ancillary System Cleaning: Internal AC components like the radiator box, blower motor, air vents, and heater element were also cleaned for a comprehensive refresh.
Electrical System Integration: Navigating the OBD2 Transition
One of the most complex aspects of the 4G93 engine swap was the electrical system. Moving from the older 4G15’s system to the 4g93 OBD2 setup required meticulous attention to wiring and ECU compatibility.
- Harness Matching: Both wiring looms from the original and donor cars were carefully disassembled and matched plug by plug. Each plug was inspected for wear and tear, and all contacts were cleaned to ensure reliable connections.
- Loom Modification: The wiring looms were meticulously modified to bypass unnecessary components from the donor car (like cruise control, factory alarm, and auto ECU) and to integrate the manual transmission setup. The automatic transmission ECU was carefully removed from the 4G93 loom, and the wiring was rerouted accordingly.
- Pin Rerouting and Secure Connections: ECU pins were rerouted to match the requirements of the manual transmission and the 1999 Lancer’s electrical system. All soldering joints were crimped and heat-shrinked for robust and insulated connections.
- Loom Resealing: Wiring looms were resealed with tape and plastic channels to maintain factory-like protection and appearance.
Alt Text: Detailed view of the meticulously reorganized and resealed wiring loom within the Mitsubishi Lancer’s engine bay after the 4G93 OBD2 engine swap.
The ECU reprogramming was crucial. Since the key barrels and key from the donor car were unavailable, the original ECU had to be reprogrammed to recognize the existing key, ensuring immobilizer functionality was maintained.
Current Challenges and Troubleshooting the 4G93 OBD2 System
Despite the successful mechanical and electrical integration, some issues surfaced post-swap, primarily related to fuel management. These problems suggest potential areas for further investigation within the 4g93 OBD2 system:
- Rich Running Condition: The car is suspected to be running rich, indicated by exhaust popping during deceleration.
- Exhaust Popping: Noticeable popping in the exhaust manifold during deceleration, resembling an anti-lag system, but unintended and indicative of an issue.
- Fuel Pump Behavior: The fuel pump runs continuously when the ignition is in the IGN position and doesn’t shut off after a few seconds as expected when the engine is not started.
- Poor Fuel Economy: The suspected rich running condition is understandably leading to worse-than-expected fuel economy.
The owner suspects the following potential causes and raises key questions:
- ECU Mapping for Auto vs. Manual: Could the 4G93 ECU, originally from an automatic vehicle, be optimized for low-RPM torque in an automatic transmission setup, potentially limiting top-end performance in the manual conversion? Is there a difference in ECU mapping between automatic and manual transmission 4G93 applications that could be contributing to the issue?
- Need for ECU Reflash/Tuning: Is an ECU reflash or custom tuning necessary to properly optimize the 4G93 for the manual transmission and address the rich running condition? Could a Tactrix OpenPort 2.0 or similar OBD2 diagnostic tool be used to log data and potentially reflash the ECU?
- Injector Size Mismatch: Could the injectors from the original 4G15 (166cc) be swapped in for testing to see if leaner fueling resolves the rich condition, without requiring immediate tuning? The 4G93 injectors are 210cc.
- OBD2 Diagnostics: Despite using a universal OBD2 scanner and finding no DTCs (Diagnostic Trouble Codes) and seemingly normal live data readings, the problems persist. Are there specific 4g93 OBD2 diagnostic procedures or tools that might provide deeper insights into these fuel-related issues?
Community Input and Next Steps
This detailed account of a 4G93 engine swap into a Mitsubishi Lancer highlights the complexities and rewards of such a project. The current challenges emphasize the importance of fine-tuning the 4g93 OBD2 system for optimal performance and efficiency after a swap.
For those with experience in similar 4G93 engine swaps or expertise in Mitsubishi ECU tuning and OBD2 diagnostics, any insights, advice, or recommendations for troubleshooting these fuel-related issues would be greatly appreciated. Specifically, information regarding ECU compatibility between automatic and manual 4G93 applications, recommended diagnostic tools for the 4g93 OBD2 system, and potential solutions for the rich running condition would be invaluable.
This project serves as a valuable case study for DIY mechanics and car enthusiasts contemplating engine swaps, particularly those involving OBD2 systems. It underscores the necessity for meticulous planning, attention to detail, and a problem-solving mindset to overcome the inevitable challenges that arise when pushing the boundaries of automotive customization.
