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Auto APPLICATION 1UZ VVT-i WIRING
What you can Expect:
The 1UZ VVT-i engine is an excellent upgrade from the 1UZ non-VVT, offering significantly more power. We specialize in converting the OEM harness on these engines to facilitate easy installation into any vehicle.
Our process begins with a thorough cleaning and inspection of the harness. During this stage, we remove any additional wiring that is not required and add any necessary components not present in the stock harness. We then inspect and replace, where necessary, the harness split tubing, which can become brittle and break over time.
We incorporate a fuse box into the harness and route the wires that used to go into the original body through the harness, creating a unified standalone system. This system includes a single connector with a pigtail for the client to connect to their vehicle to get the engine running. This connector, referred to as a client plug, consists of three wires essential for the operation of the engine: Ignition, Start signal, and Fuel pump power supply. The same connector also provides dashboard signals such as rev counter signal, engine temperature, charge light, and oil pressure light. Depending on the original harness sent in for modification, you may also receive the air conditioning compressor electric clutch trigger.
For automatic configurations, you will receive an additional client plug dedicated to the transmission functions. This plug includes Park, Neutral, Drive, Overdrive, three, two, and low. As an automatic, we also wire in your cruise control as a standard, whether you use it or not. With the 1UZ VVT, you will have an OBD2 port built into the harness, allowing you to read live data and check diagnostics on your system. This is a valuable feature to have in your system.
We charge a base price of $690 for a 1UZ VVT automatic configuration. This price is solely for the wiring modifications and does not include connectors or immobilizer bypass. Connectors vary from harness to harness and can’t be calculated until the harness has been inspected. They vary in price but on average run around $6 per connector installed.
The immobilizer has an additional cost of $90 to be removed from your ECU.
Once the modifications have been made to the harness and ECU, we install your harness onto one of our test engines. We create a walkthrough and test run video for your records, as well as a welcome pack, client plug pinouts, and images of the harness, along with shipping information. This is shared with our client through a shared folder link. This gives everyone peace of mind that things have been done correctly and there can be no mistakes on the system. We take great pride in our work and hope it will bring pleasure to our client for many years to come. Please refer to the “1UZ VVT-i OEM ECU Reliability” section for more information regarding the ECUs in these systems.
An example of what you will receive in video:
1UZ VVT-i Automatic Application Test Run Video (youtube.com)
1UZ VVT-i OEM ECU Reliability
The 1UZ-FE Original Equipment Manufacturer (OEM) Engine Control Units (ECUs) are known for their exceptional reliability. They seldom require replacement, and when they do, it’s generally due to physical damage or water damage. The cost of replacement is quite reasonable, with units available for as little as $50 from a junkyard or around $70 on eBay, including free delivery.
It’s important to note that virtually all 1UZ VVT ECUs come with an immobilizer. This would either need to be deleted or made functional depending on the specific requirements of your setup.
These ECUs have read-only memory and cannot be flashed. While this does not affect performance, it can impact the Diagnostic Trouble Codes (DTCs) when opting for a manual application. Transmission-related DTCs for these ECUs can be disregarded. If you prefer to remove the DTCs, there is an option to utilize a transmission emulator. This device tricks the ECU into believing the transmission is present, but it may also result in error codes for the EVAP and secondary O2 sensors. Our recommendation is to simply ignore the DTCs that are not relevant to your engine swap. This approach ensures a smoother transition and optimal performance for your engine.
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
Lexus V8 Enignes LLC
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