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Manual Application 1UZ-FE Wiring
What you can Expect:
Our service is designed to be adaptable and versatile, capable of being implemented in any vehicle. It essentially creates a standalone system that can even be initiated on the garage floor by simply connecting two wires and a fuel pump.
We integrate a fuse box into the engine harness to mimic the wiring found in the original vehicle. This fuse box houses all the necessary relays and fuses for the system. For non-VVT engines, we incorporate diagnostics via an LED in the fuse box that will flash out codes for diagnostics as it operates on OBD1. For non-VVT engines from 1995 onwards, you will have access to OBD2, which can be read via a phone or diagnostic tool through an OBD2 diagnostic connector. This provides a code description of the system. On non-VVT engines, there is no immobilizer, with the exception of the 1997 model. We go through the harness and remove any unnecessary circuits like EGR, unless you would like to keep it, but most clients prefer it removed.
When we construct the fuse box, we replace any connectors you would like to have replaced and tape the entire harness with a cloth tape. The harness is then tested on one of our test engines to ensure everything is functioning properly. We document this process with a video and pictures of the harness, which we send to you through a shared folder. This folder also includes the welcome pack, client plug pinouts, return shipping label, and any other information you may require.
We wire in a client plug in the form of a pigtail for you to connect to your vehicle. The client plug houses three wires to get the engine to run: ignition, fuel pump power supply, and start signal. It also houses four wires for your cluster: charge light, rev counter signal, oil light, and temperature gauge.
We require the engine harness and the ECU for our services. You can also send the starter harness and front harness in the case of non-VVT if you would like them serviced. We have a turnaround time of two to three weeks to complete the job, depending on the queue we have in the shop at the time of arrival.
We charge $590 for LS400 and $690 for SC400 for performing the wiring modifications on the harness. SC harnesses are more complex and require a total reconstruction to tidy them up and make them suitable for engine swaps. The decision to replace the connectors is up to you. The quantity varies from harness to harness. Some clients want them all replaced as they can become old and brittle, while others have a great harness that doesn’t need any replacements. Others only want damaged connectors to be changed. They cost on average around $6 each installed.
If you have the connectors that went from the ECU to the body harness, then please send them along. We look forward to assisting you with your engine modification needs.
An example of what you will receive in video:
1UZ-FE Manual Setup Wiring (Scott's S13 Engine Swap) (youtube.com)
1UZ-FE OEM ECU Reliability
We would like to inform you that the service for modifying 1UZ non-VVT engine harnesses will soon be discontinued. This decision has been made due to the fact that the ECUs for these engines often require a rebuild, which can lead to unforeseen expenses for the customer. We do not offer computer rebuilding services, and unfortunately, ECU rebuilders cannot guarantee that your rebuilt ECU will function as expected.
As an alternative, we recommend opting for aftermarket engine management for non-VVT 1UZ engines. This approach eliminates the risk of unexpected costs and provides you with a programmable ECU. It’s important to note that the OEM non-VVT 1UZ ECUs have read-only memory and cannot be modified. This makes aftermarket solutions a more flexible and reliable choice for managing your engine’s performance.
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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