Auto APPLICATION 1UZ VVT-i WIRING

What you can Expect:

⚙️ 1UZ-FE VVT-i AUTO Conversion Wiring – Supported Platform

Starting at $750 — Typical cost: $1000–$1,150 depending on harness condition and connector replacement.

The 1UZ-FE VVT-i is a major upgrade over the non-VVT version, offering more power, better efficiency, and modernized electronics. We specialize in converting OEM harnesses for automatic transmission setups, delivering a plug-and-play solution tailored to your vehicle.

✅ What’s Included in Your AUTO Conversion

✔️ Harness Inspection & Refurbishment We begin with a full cleaning and inspection of your harness. During this process:

Unnecessary wiring is removed for standalone operation
Missing components are added as needed
Brittle or broken split tubing is replaced for long-term durability

✔️ Standalone System Conversion We integrate a fuse box and reroute body wiring into the harness, creating a clean, unified standalone system.

✔️ Simplified Vehicle Integration via Client Plug Your harness includes a client plug with a pigtail connector for easy integration. This plug supports:

Essential startup wires:
- Ignition
- Start signal
- Fuel pump power supply
Dashboard signals:
- Tach signal
- Temp sensor
- Charge light
- Oil pressure light
Optional signals (based on original harness):
- A/C compressor clutch trigger

✔️ Automatic Transmission Support An additional client plug is included for transmission functions:

Park
Neutral
Drive
Overdrive
Three
Two
Low

Cruise control wiring is also included by default—even if unused.

✔️ OBD2 Diagnostics Integration Unlike the older OBD1 system, the VVT-i platform supports full OBD2 diagnostics:

Read live engine data
Diagnose issues with a standard OBD2 scanner
Improve troubleshooting and tuning

📦 Testing & Documentation

Once your harness and ECU are modified, we:

✅ Install your harness on one of our test engines
✅ Record a full walkthrough and test-run video
✅ Share a folder containing:
- Welcome pack
- Client plug pinouts
- Detailed harness images
- Shipping and install info

This ensures full transparency and confidence that your system is wired and tested before shipment.

🔍 Why Choose the VVT-i Version?

Feature

VVT-i 1UZ-FE

Non-VVT 1UZ-FE

Ignition System

Coil-on-plug

Distributor-based

ECU Support

Flashable, OBD2

Non-programmable, OBD1

Diagnostics

Full OBD2 capability

Limited fault reporting

Performance

Improved torque & tuning

Less efficient, outdated

The VVT-i ECU is more reliable and does not require rebuilding—unlike the non-VVT version.

🧾 Pricing Notes

💰 Pricing details are available on the client form. Connector replacement is quoted based on harness condition.

📣 Final Notes

We take pride in delivering clean, reliable wiring solutions for your 1UZ-FE VVT-i AUTO swap. For more on ECU reliability, see our "1UZ VVT-i OEM ECU Reliability" section.

Ready to get started? Contact us today for a hassle-free conversion! 🚗⚡

An example of what you will receive in video:

1UZ VVT-i Automatic Application Test Run Video (youtube.com)

1UZ-FE VVT-i OEM ECU Reliability

The 1UZ-FE VVT-i ECU is a reliable and cost-effective engine control unit that rarely requires replacement. When issues do arise, they are typically caused by physical damage or water exposure, rather than internal failures like those found in older non-VVT ECUs.

💰 Cost of Replacement:

Used ECUs can be found as low as $50 from junkyards
Online sources such as eBay often list them for around $70, often with free delivery

Understanding the Immobilizer System

Virtually all 1UZ-FE VVT-i ECUs come with an immobilizer, which must be addressed before the ECU can function properly in a swap. You have two options:

Immobilizer Bypass ($140) – We remove the immobilizer, allowing the engine to run in any vehicle without security restrictions.
Keep the Immobilizer Functional – If your setup includes the original key, transponder, and immobilizer system, we can wire it in accordingly.

ECU Limitations & Handling Diagnostic Trouble Codes (DTCs)

🔹 Read-Only Memory (ROM): The 1UZ-FE VVT-i ECUs cannot be flashed or reprogrammed, meaning any DTCs related to missing components (e.g., automatic transmission) will remain unless addressed through hardware modifications.

🔹 How to Handle Transmission DTCs in Manual Swaps:

Option 1: Simply ignore the automatic transmission DTCs. These do not affect engine performance.
Option 2: Use a transmission emulator, which tricks the ECU into thinking the transmission is still present. However, this may also introduce EVAP and secondary O2 sensor error codes, which would need to be ignored.

Our recommendation is to disregard transmission-related DTCs when doing a manual swap, as they do not impact drivability or engine performance. This approach provides the smoothest and most hassle-free integration for your 1UZ-FE VVT-i swap.

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Additional Information

The Toyota 1UZ-FE 4.0L Engine: Specifications and Reliability

The 1UZ-FE, the first in the UZ engine series, was a 4.0-liter V8 gasoline engine featured in Toyota and Lexus luxury and sports cars from 1989 to 2002, before being replaced by the 3UZ-FE engine. It succeeded Toyota's older V family engines, which were used from the 1960s through the 1990s. The 1UZ-FE engine is characterized by an aluminum cylinder block with thin cast-iron cylinder liners and a 90-degree angle between the cylinder banks, offset by 21 mm. It features six main bearings and a forged steel crankshaft with eight counterweights. To minimize rotational mass, it includes lightweight forged steel connecting rods, aluminum pistons, and induction-hardened connecting rod pins. In late 1994, the 1UZ-FE received updates such as a lighter crankshaft, connecting rods, shorter piston pins, and redesigned pistons. Its quiet and smooth operation is largely due to liquid-filled compound engine mounts. In 1997, it was further refined with a more rigid cylinder block to enhance quietness.

The 1UZ engine is engineered more like a racing powerhouse than your typical road car engine. It's equipped with an eight counterweight crankshaft, and its components are designed to be lightweight. The bore and stroke dimensions are almost perfectly square, which is quite unique. But the standout feature has to be the DOHC 32-valve aluminum cylinder heads. This is a stark contrast to the older V8 engines, which usually had a single camshaft in the cylinder block and OHV heads with just two valves per cylinder. The 1UZ-FE, on the other hand, features two camshafts per head—one for intake and one for exhaust, with four valves for each cylinder. The intake camshafts are belt-driven, while the exhaust camshafts are gear-driven by the intake ones. Instead of using hydraulic lifters, this engine uses solid aluminum alloy valve lifters and steel outer shim type valve adjusters. Initially, the valve stem diameter was 6.0 mm for both intake and exhaust valves, with the intake valves being 33.5 mm in diameter and the exhaust valves 28.0 mm. But in a late 1997 update, the valve diameters were increased to 34.5 mm for intake and 29.0 mm for exhaust, and the stem diameter was reduced to 5.5 mm.

The initial design of the 1UZ-FE engine showcased a simple ignition system, comprising two distributors along with two ignition coils. This engine initially employed multi-port fuel injection (MFI) technology until 1994, which was then upgraded to sequential multiport fuel injection (SFI). The Non-VVT-i variant came with a mechanical throttle body and was fitted with an aluminum intake manifold. Additionally, it featured an Exhaust Gas Recirculation (EGR) system, which was responsible for redirecting a portion of the exhaust gases back into the combustion chambers. These gases were cooled by the engine's coolant system located at the rear before re-entry. However, the EGR system was phased out in 1997. As for the exhaust configuration, it boasted stainless steel headers and monolithic-type three-way catalytic converters.

Engine Specifications:

- Manufacturer: Tahara plant

- Production Years: 1989-2002

- Cylinder Block Material: Aluminum

- Cylinder Head Material: Aluminum

- Fuel Type: Gasoline

- Fuel System: Fuel injection

- Configuration: V

- Number of Cylinders: 8

- Valves Per Cylinder: 4

- Valvetrain Layout: DOHC

- Bore: 87.5 mm (3.44 in)

- Stroke: 82.5 mm (3.25 in)

- Displacement: 3,968 cc (242.1 cu in)

- Engine Type: Four-stroke, naturally aspirated

- Compression Ratios:

- 10.0:1

- 10.4:1 (since late 1994)

- 10.5:1 (since 1997 for VVT-i engines)

- Power Output:

- 251-261 hp (191-195 kW) at 5,400 rpm (non VVT-i)

- 290-300 hp (216-224 kW) at 5,900-6,000 rpm (with VVT-i)

- Torque:

- 260-269 lb-ft (353-365 Nm) at 4,400 rpm (non VVT-i)

- 300-310 lb-ft (407-420 Nm) at 4,000-4,100 rpm (with VVT-i)

- Engine Weight: 364 lbs (165 kg)

- Firing Order: 1-8-4-3-6-5-7-2

- Engine Oil Weight: 5W-30

- Engine Oil Capacity:

- 5.0 liters (0.3 for oil filter) for 1989-1994 models

- 5.1 liters (0.3 for oil filter) for 1994+ models

- Oil Change Interval:

- 6,000 miles (10,000 km) or 12 months for 1989-1994 models

- 9,000 miles (15,000 km) or 12 months for 1994+ models

- Applications: Lexus GS 400, Lexus LS 400, Lexus SC 400, Toyota Aristo, Toyota Celsior, Toyota Crown, Toyota Soarer