4AG Engine

4AG Engine

The Toyota 4AG DOHC 16V engine




General Information


Cylinders4
Displacement1587cc
Firing Order1342
Cylinder Orientation (from drivers seat)
Cyl1 closest to timing belt 





Model Variants

4AGE 1st gen Blue Early Big Port - USDM Vane MAF, JDM MAP,  T-VIS @4200rpm, 9.4:1 comp. Batch fire injection, distributor ignition, 182cc injectors, 16 valve head
4AGE 2nd gen Red & Black Late Big Port - As above but all are MAP
4AGE 3rd gen Red Small Port - 10.3:1 comp, No T-VIS, stronger internals,USDM use MAF, 235cc injectors
4AG 20V 4th gen "Silver Top" - Switched inlet cam timing, 3x inlet valves per cylinder, sequential injection, 10.5:1 comp, ITB intake, vane MAF, distributor ignition, 295cc injectors
4AG 20V 5th gen "Black Top" - Switched inlet cam timing, 3x inlet valves per cylinder, sequential injection, 11.0:1 comp, ITB intake, MAP sensor, 
4AGZE Big Port - ECU controlled clutched supercharger, batch fired injection, waste spark ignition, 365cc injectors, MAF.
4AGZE Small Port - As above, MAP sensor




Sensor Information

Distributor

There are a number of distributors found on 4AG engines.
Variants include:
1. 24x with 4x up the top
2. 4x with 1x up the top
3. 24x with 1x up the top
4. 24x with 1x up the top cam sensor (4AGZE)

There has been a variant sited as having just 4x down the bottom, but this is more likely from a 4A and not a 4AG.

Variant 1 can be used but requires 3 of the 4 teeth cut off so the distributor is left with 24x and 1x
Variant 2 is supported and configured as a Generic Standard Full Cycle Sync
Variants 3 and 4 are supported and configured as the Toyota 4AG trigger type


DISTRIBUTOR WIRING

All models use Reluctor sensors. 

Most models have the negative side of the sensors all linked together and connected to Signal Ground (G-).  As such the blue Signal Ground wire should be used and not the Trigger- or Home- wires.  In the ESP software the Ground Reference should then be Enabled. 

4AGE Big Port (24x + 4x after modification)
OEM Wire Colour
Signal Name
Description
Haltech Wiring
Red (24x)
NE +
24x signal positive
Trigger +
White (24x)
NE -
24x signal negativeTrigger -
Red (1x)
G+
1x signal positive
Home +
White (1x)
G-
1x signal negative
Home -


4AG 20V

OEM Wire ColourSignal NameDescriptionHaltech Wiring
Pin D - BlackNE24x signalTrigger +
Pin C - RedG11x signalHome +
Pin B - GreenG21x signal + 360degNo connection
Pin A - WhiteG-Signal GroundSignal Ground


4AGZE

OEM Wire ColourSignal NameDescriptionHaltech Wiring
RedNE24x signalTrigger +
GreenG11x signalHome +
YellowG21x signal + 360degNo connection
WhiteG-Signal GroundSignal Ground

Trigger/Home Wiring Hack

For applications where there is a dual Hall Effect pickup in a CAS or Distributor there is a quick wiring hack that allows the Home+ signal to be incorporated in the Trigger 4-core shielded cable.  This can make the wiring much cleaner and easier.  

To do this we will be relocated the wiring at the ECU Connector so that the unused Trigger- wire is instead placed onto the ECU pin for Home+.  This means that the Trigger 4-core cable now has 12V+, Ground, Trigger+ and Home+ all in the one cable.   The GREEN wire that is labelled at Trigger- is now actually the Home+.

For Elite 550/750/950 models
1. Unplug the Main Connector at the ECU end.
2. Unlock the connector by pushing in the large white tab on the connector until it clicks. This will cause the two smaller white tabs to pop up on the other side.
3. Remove the Yellow Home+ wire from pin 32.  Insulate this wire, it will not be used.
4. Remove the Green Trigger- wire from pin 33 and move it to pin 32.  Push it all the way until you can see the metal pin clearly from the pin side of the connector and it looks the same as all other pins.
5. Lock the connector by pushing back down the 2x white tabs until they click into position.

For Elite 1000/1500/2000/2500 models
1. Unplug the smaller 26-pin Main Connector at the ECU end.
2. Unlock the connector by pushing in the large white tab on the connector until it clicks. This will cause the two smaller white tabs to pop up on the other side.
3. Remove the Yellow Home+ wire from pin 2.
4. Remove the Green Trigger- wire that is in pin 5 and move it to pin2. Push it all the way until you can see the metal pin clearly from the pin side of the connector and it looks the same as all other pins.
5. Lock the 26-pin connector by pushing back down the 2x white tabs until they click into position.






Common 4AG Trigger Issues

It is a common issue to see 4AG Reluctor trigger systems to be biased towards the negative side of 0V, usually crossing at -0.25V. 
To ensure correct operation it is often necessary to use a customer trigger configuration as below.

Trigger Configuration



   
   












Ignition Coil and Igniter Module

For all models the body of the igniter must be grounded to the chassis.

16V Distributor Models

These models have an old old-filled tube coil design with an external igniter mounted to the side of the coil




AE82 Wiring
Wire ColourFunctionHaltech Connection
Black/YellowIGF (Fail Signal)---
Black/BlueIGT Signal From ECUIgnition Output 1 (Yellow/Black)
Black/Orange12V+ Switched---
BlackTacho Signal---
BlackCoil -ve---

AE92 Wiring
PinFunctionHaltech Connection
1IGF (Fail Signal)---
2IGT Signal From ECUIgnition Output 1 (Yellow/Black)
312V+ Switched---
4Tacho Signal---
5Coil -ve---



20V Distributor Models

These use a newer style coil with a higher output and an external separate igniter module.


Pin
Function
Haltech Connection
A
IGF (Fail Signal)
---
B
Signal From ECU
Ignition Output 1 (Yellow/Black)
C
12V+ Switched
---
D
Tacho Signal
---
E
Coil -ve
---




4AGZE Waste Spark Model





6-pin Connector
Wire
Function
Haltech Connection
Brown
12V+ Switched
---
Grey
IGF
---
Pink
IGT Signal from ECU 1
Haltech Ignition Output 1 (Yellow/Black)
Yellow
Tacho Signal
---
---

---
White
IGD Signal from ECU 2
Haltech Ignition Output 2 (Yellow/Red)

2-pin Connector
Wire
Function
Haltech Connection
Light Blue
Coil -ve 1+4
---
Black
Coil -ve 2+3
---
















Throttle Position Sensor

The throttle position sensor has the normal variable voltage output, but also has a closed throttle switch.  This switch is not connected to the Haltech ECU.

PinDescription
Haltech Connection
15V+
5V+ (Orange)
2Signal
Spare AVI (AVI-10 White)
3Idle Switch - Not Used
---
4
Signal Ground
Signal Ground (Black/White)










MAP Sensor


AE92 MAP
PinDescription
1 - BrownSignal Ground
2 - YellowSignal
3 - Light Green/Red5V+

Calibration: Use "xxxxxxxx.cal"









Idle Valve

4AG20V

The 4AG 20V engine uses a dual-solenoid system. This uses 2x ECU outputs and a 12V+ power supply.  One signal opens the valve, the other closes it.  
It is configured in the software as a BAC 3-wire

Pin
Function
Haltech Connection
1
Open Signal
Spare Output
2
Power
12V+ Switched
3
Close Signal
Spare Output










Coolant Temperature Sensor

Located on the rear of the engine above the gearbox bellhousing.

4AG20V Coolant Temp Sensor

Wiring is not polarity sensitive

Calibration: Use "Temperature - Toyota 1FZ-FE Coolant Sensor.cal"
Created for Haltech ECUs using a 1k pullup to 5V









Air Temperature Sensor


Wiring is not polarity sensitive.

Calibration: Use "Temperature - xxxxxx.cal"
Created for Haltech ECUs using a 1k pullup to 5V











OEM ECU Information

AE86/92





  

   



AE101 Silvertop



         






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