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Haltech-1UZ-Technical-Information Goleby's Parts

Haltech - 1UZ Technical Information

Information on the Toyota 1UZ-FE Engine
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

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


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
Soarer SC400
Aristo GS400
Celsior LS400
Land Cruiser (MY98-05)
4Runner (MY99-04)
Tundra (MY99-04)
GX470 (MY02-04)
LX470 (MY98-05)
Sequoia (MY00-04)
Land Cruiser (MY05-11)
4Runner (MY05-09)
Tundra (MY04-09)
GX470 (MY04-09)
LX470 (MY05-07)
Sequoia (MY04-09)
3UZ LS430
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 Configuration

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.
1UZ VVTi and all 2UZ and 3UZ Configuration
12x on the Left and 36-2 on the Right
Tooth Crank Trigger

Crank Sensor

A Reluctor crank position sensor is used.
Crank Sensor
NE Pick Up Coil
Crank Angle Sensor

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.
1UZ Cam Sensor
Cam Position Sensor

VVTi models

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


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

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.
Toyota 1UZ-FE Ignition

Direct Fire Coil Models

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

Dwell Time

Distributor Models
Dwell Time Distributor Models
Direct Fire Models
Dwell Time 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+
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
3 Signal Ground Signal Ground
4 5V+ 5V+
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.
Throttle Position Sensor
OEM Wiring
Haltech Wiring
Signal (Spare AVI)
Closed Throttle Switch - NOT USED
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.
MAP Sensor
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.
Haltech - 1UZ
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.
Idle Control Motor
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.
Haltech - 1UZ
Wiring is not polarity sensitive
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 -"
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
Haltech - 1UZ
Wiring is not polarity sensitive.
Calibration: Use "Temperature - GM Air"
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.
Haltech - 1UZ
Recommended Knock Sensor.  Haltech HT-011100
Haltech - 1UZ
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.
Haltech - 1UZ
Haltech - 1UZ
OEM Wire Colour
Signal Ground
Air Temperature (AVI)
MAF Signal (SPI or DPI)
Signal Ground
Haltech - 1UZ
Haltech - 1UZ
Haltech Connection
B+ (Power)
E2G (MAF Ground)
Signal Ground
VG (MAF Signal)
THA (Air Temp Signal)
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.
Haltech - 1UZ
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.
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.
Haltech - 1UZ

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
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.
Haltech - 1UZ
LS400 (MY98-00)
Haltech - 1UZ   Haltech - 1UZ

Soarer UZZ30
Haltech - 1UZ   Haltech - 1UZ
Haltech - 1UZ   Haltech - 1UZ


Haltech - 1UZ   Haltech - 1UZ
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