September 14, 2023

Haltech - 1UZ Technical Information

Information on the Toyota 1UZ-FE Engine

Haltech ECU Options

All Haltech ECU models can run the engine. Elite 1000 and higher is required to control the factory stepper motor idle valve. Elite 950, 2000, and 2500 are required for sequential injection upgrade.

General Information

Cylinders	8
Displacement	1UZ 3969cc 242ci 2UZ 4663cc 284ci 3UZ 4292cc 262ci
Firing Order	1,8,4,3,6,5,7,2
Cylinder Orientation	1,3,5,7 on LHS (from drivers seat

Model Variants

There are a number of variants of the 1UZ engine.

1UZ-FE (1989-1995)

4L V8, alloy block, 10.0:1 comp, 12x crank trigger, 1x cam trigger

1UZ-FE (1995-1997)

10.4:1 comp, 12x crank trigger, 1x cam trigger

1UZ-FE VVTI (1998-on)

10.5:1 comp, Variable Cam Timing on Inlet Cams (continuous type), 36-2 crank trigger, 3x cam trigger

2UZ-FE (1998-2005)

4.7L V8, iron block, 36-2 crank trigger, 3x cam trigger

2UZ-FE VVTi (2004-on)

Variable Cam Timing on Inlet Cams (continuous type), electronic throttle, 36-2 crank trigger, 3x cam trigger

3UZ-FE VVTi

4.3L V8, Alloy block, Variable Cam Timing on Inlet Cams (continuous type), 36-2 crank trigger, 3x cam trigger

Common Models

Engine Type	Common Vehicles
1UZ	Soarer SC400 Aristo GS400 Celsior LS400 Crown
2UZ	Land Cruiser (MY98-05) 4Runner (MY99-04) Tundra (MY99-04) GX470 (MY02-04) LX470 (MY98-05) Sequoia (MY00-04)
2UZ VVTi	Land Cruiser (MY05-11) 4Runner (MY05-09) Tundra (MY04-09) GX470 (MY04-09) LX470 (MY05-07) Sequoia (MY04-09)
3UZ	LS430 GS430 Soarer SC430 Crown Majesta Hongqi HQ430

Sensor Information

Crank/Cam Sensor

This engines uses a Crank Position Sensor and 2x Cam Position Sensors (1x per bank).

Early 1UZ

These models use a 12x tooth crank trigger and a 1x tooth cam trigger. Configuration is shown below.

1UZ VVTi and all 2UZ and 3UZ

These models use a 36-2 tooth crank trigger and a 3x tooth cam trigger. Configuration is shown below.

12x on the Left and 36-2 on the Right

Crank Sensor

A Reluctor crank position sensor is used.

Cam Sensor

Reluctor cam sensors are used. 1UZ motors have these located under the cam drive pulley on each bank. The cam pulley has a backing plate with a single tooth.

VVTi models

These use the same sensor arrangement with a 3-tooth backing plate on the cam pulley.

Distributor

The 1UZ-FE has twin distributors. These do not contain any advance mechanism and are simply there to distribute spark to each cylinder.

Ignition Coils and Igniters

Early 1UZ models have 2x igniters and 2x coils. The igniters have the same wiring.

All models use Constant Charge with a Falling output edge.

Direct Fire Coil Models

All models with Direct Fire ignition feature coils with internal igniter modules.

Dwell Time

Distributor Models

Direct Fire Models

DBW Throttle System

Models that have the ETCS-i throttle system are not supported by Haltech.

Models that use a normal cable throttle, or have full DBW (no throttle cable) are supported.

All variants use a single throttle body.

DBW Throttle Wiring

Position Sensors

Pin	Description	Haltech Connection
1	5V+	5V+
2	TPS2	AVI3
4	TPS1	AVI2
5	Signal Ground	Signal Ground

Drive Motor

Pin	Haltech Connection
3	DBW1
6	DBW2

DBW Accelerator Pedal Position Sensors Connection

Pin	Description	Haltech Connection
1	Signal Ground	Signal Ground
2	APP2	AVI5
3	Signal Ground	Signal Ground
4	5V+	5V+
5	APP1	AVI4
6	5V+	5V+

Throttle Position Sensor

Early 1UZ models use a cable throttle with a conventional throttle position sensor.

This engine uses a cable operated throttle body with a position sensor.

OEM Wiring	Haltech Wiring
A	5V+
B	Signal (Spare AVI)
C	Closed Throttle Switch - NOT USED
D	Signal Ground

MAP Sensor

These engines do not come with a MAP sensor.

Use the internal MAP sensor that comes with your ECU. For higher boost levels an external MAP sensor should be used instead, connected to a spare AVI.

Variable Cams

Engines with VVTi have Toyotas Gen 3 continuously variable cam control. The ECU uses a 3x tooth cam sensor on each inlet cam to know the position of the camshafts relative to the crank position. A duty signal is sent to each cam control solenoid. The solenoid regulates oil pressure being fed into the cam control mechanism to advance or retard the cams to their target position using closed-loop. They cannot be sent to a specific position using open loop.

Idle Valve

The cable throttle 1UZ engine uses a Stepper Motor idle valve controlled via the Stepper Outputs. It will not work on Elite 550/750/950 ECU models.

Pin	Haltech Connection
A	Stepper 4
B	12V+ Ign Switch or No Connection
C	Stepper 3
D	Stepper 1
E	12V+ Ign Switch or No Connection
F	Stepper 2

Drive Type: Low Side if 12V+ is connected. Both if 12V+ is not connected

Steps:240 Speed:75

Coolant Temperature

Located near the RHS Distributor.

Wiring is not polarity sensitive

Pin	Haltech Connection
1	Any Spare AVI*
2	Signal Ground

An AVI with a selectable Pullup should be used. If not and external 1k pullup to 5V should be connected.

Calibration: Use "Temperature - xxxxxxx.cal"

Created for Haltech ECUs using a 1k pullup to 5V

Air Temp

An air temperature sensor is incorporated in the MAF Sensor. If the MAF is deleted then an external Air Temperature Sensor needs to be installed in the intake, preferably in the plenum near to where the MAP sensor connects.

Haltech 1/8" NPT Air Temp Sensor

Wiring is not polarity sensitive.

Calibration: Use "Temperature - GM Air Sensor.cal"

Created for Haltech ECUs using a 1k pullup to 5V

Knock Sensor

The 1UZ has 2x resonant style single-wire knock sensors located in the intake valley near the starter motor. Although they can be used they are not as reliable as newer donut style resonant sensors.

Recommended Knock Sensor. Haltech HT-011100

MAF Sensor

Although most users of Haltech ECUs will be deleting the MAF, it is possible to use a MAF if you prefer. It also incorporates an Air Temperature Sensor, so if the MAF Sensor is removed a new Air Temperature Sensor must be installed in the intake.

1UZ Early

The early 1UZ use a Frequency based MAF Sensor. It is not a normal 0-5V signal.

Pin	OEM Wire Colour	Connection
1	Brown	Signal Ground
2	Yellow/Black	Air Temperature (AVI)
3	Yellow/Green	MAF Signal (SPI or DPI)
4	Blue/Red	5V+
5	Brown	Signal Ground

2UZ

Pin	Description	Haltech Connection
1	B+ (Power)	12V+
2	E2G (MAF Ground)	Signal Ground
3	VG (MAF Signal)	SPI or DPI
4	THA (Air Temp Signal)	AVI
5	E2 (Air Temp Ground)	Signal Ground

O2 Sensors

1UZ engines have 4x Narrowband 4-wire O2 sensors. Narrowband sensors are not useful for tuning and are used primarily for catalytic converter efficiency.

O2 Sensor Wire Colours	Haltech Connection
Black (Signal)	AVI 1 or AVI 6
Grey	Signal Ground (Black/White)
White	12V+ Switched
White	Chassis Ground (not Signal Ground) or Spare Output

It is possible for the ECU to supply a duty signal to the Heater Ground, with many OEM ECUs doing this. Haltech ECUs can also perform this task and a spare Injector or Stepper Output should be used.

O2 Sensors can use various wattage heater elements, with 12W and 18W being common. For 18W units it is advised to not supply more than ~50% duty to prevent excessive current being applied to the ECU output.

For post-cat sensors it is advised to not enable the heater ground control until the engine is at full operating temperature. This is to prevent moisture in the exhaust from a cold started engine from damaging the heater element. Many OEM strategies involve not enabling the heater until the engine have been driven above a set speed for a set amount of time.

Adding a Haltech Wideband Kit (highly recommended)

For correct operation a Haltech WB2 kit is highly recommended for this application, with the provided 4.9 sensors replacing the pre-cat sensors. Swapping the sensors is accessed only from below the vehicle. Sensors use a 22mm socket or spanner to remove and replace.

Vehicle Speed Sensor

This engine uses a Reluctor Vehicle Speed sensor.

Reluctor Speed Sensor Wiring

OEM Wiring	Description
Signal +	Any Spare SPI
Signal -	Signal Ground

Injector Data

Early 1UZ engines have only 4x injector outputs from the OEM ECU, run as semi sequential. They are joined in the OEM wiring as 1+7, 2+8, 3+5, 4+6

1UZ VVTi and all 2UZ and 3UZ engines have sequential injection

Flow

The injector flow rate is measured with the injectors held wide open at 100% duty. For fuel systems with a fixed regulator pressure (often returnless systems) that is not referenced to manifold pressure the flow needs to be mapped over Manifold Pressure for accurate tuning.

Early 1UZ-FE have 240cc/min injectors.

Dead Time

When an injector is commanded to open for a certain amount of time, the dead time is the amount of time the injector is not actually open during this period. It covers the time to energise the solenoid and begin to open and the time to close as well. There are also transient periods during which the injector is opening and closing where fuel flow is not at full capacity so this lost peak flow period is also taken into account.

OEM ECU Information

There are a number of different ECU connectors found on the 1UZ, 2UZ and 3UZ ECUs.

1UZ-FE ECU