GTA IV Complete Modding Setup Guide with FusionFix (Tested & 100% Working)

Grand Theft Auto IV still holds up as one of the grittiest open-world games ever made, but the PC port is rough. Broken physics above 60 FPS, missing songs, random crashes — Rockstar never fixed it. The community did. This GTA IV modding setup guide with FusionFix walks you through the exact process we use on our test rigs. Tested & 100% Working on the Steam Complete Edition and retail copies.

What Is FusionFix and Why Every GTA IV Player Needs It

FusionFix is a community plugin by ThirteenAG that patches GTA IV's worst problems: broken cutscene cameras, busted recoil, flickering shadows, and the infamous high-FPS physics bugs. It also adds borderless windowed mode, proper FOV sliders, and gamepad improvements. If you install only one mod, make it this one.

What You Need Before Modding GTA IV

• A clean GTA IV install (Steam Complete Edition 1.2.0.43 or downgraded 1.0.8.0)
• Ultimate ASI Loader (from ThirteenAG's GitHub)
• The latest FusionFix release
• DXVK 32-bit build (optional, massive FPS boost)

Pro tip: back up your entire GTA IV folder before touching anything. Five minutes now saves a full reinstall later.

How to Install FusionFix in GTA IV (Step-by-Step)

1. Install the Ultimate ASI Loader. Download it and drop dinput8.dll into your main GTA IV folder, right next to GTAIV.exe or LaunchGTAIV.exe.
2. Extract FusionFix. Copy the plugins folder from the archive into the same directory. That's the core install — extract and play.
3. Tweak the INI. Open GTAIV.FusionFix.ini inside the plugins folder. Set your frame limit, enable borderless windowed mode, and turn on the fixed cutscene FOV.
4. Launch the game. Skip the launcher intro videos and load a save. If Niko walks out the door without a crash, you're golden.

Boost FPS with DXVK

GTA IV runs on ancient DirectX 9, and modern GPUs hate it. Drop DXVK's 32-bit d3d9.dll into the game folder to translate calls to Vulkan. On our test machine, stutter vanished and average FPS jumped 20–30%. Pair it with FusionFix's frame limiter for smooth, tear-free gameplay.

Common GTA IV Modding Errors and Quick Fixes

Best Mods to Install After FusionFix

Once the base is stable, level up Liberty City with Various Fixes, Console Visuals for that classic look, and the IV SDK for script mods. Install one at a time and test between each — no crash issues that way.

Follow our simple step-by-step guide and Liberty City runs better than Rockstar ever shipped it. Got a mod combo you love? Drop it in the comments here at AllTypeHacks.