First, remove air filter. Then, remove mechanical injectors with distributor.
Airflow sensor plate is not needed any more. Remove it, and fix moving part beneath with a plastic strap.
To install injectors properly, you need to cut part of the intake manifold like on photo below
Then, install injector sleeves using engine sealant.
Insert injectors. First - into the fuel rail. Then - into the manifold.
Bend the metal brackets of the rail and drill an hole on each bracket to insert the screw that will hold it to the intake manifold.
The stock air supply scheme from the Idle valve cannot be used.
Install new idle air supply fitting under the throttle. Connect the air supply hose from the idle valve.
Idle valve is left connected to the stock ECU.
Before installing, clean valve internals with carburettor cleaner, and lubricate with the oil. Don't use WD40, it is not lubricant.
MAP sensor location is really important to ensure a good engine operation. Locate MAP sensor exactly as shown on photo.
Drill 13mm hole for the sensor and 8mm for the bolt that will secure it. Cover the drill tip with grease to catch the debris, it is reccomended to clean the intake manifold after drilling the hole to ensure that no metal debris is left in it.
Seal hole with a sealant. Sufficient sealing paste must be applied because the surface of the intake manifold is rough.
Secure sensor with included screw. Apply sealant to the thread, to prevent air leaks and unscrewing.
Never install any sensor with the wires upwards, water will flow off the cable and shortcircuit the sensor.
It is prohibited to install MAP sensor in place of cold start injector.
ECU and wiring
Disconnect battery when working with the electrical system. Connect battery back only when engine have to be started.
ECU is dust and splashproof. It cannot withstand continuous water contact or pressurized water, so it is reccomended to install it in a dry and safe place. Do not install ECU with cable upwards. In this case, water and moisture will flow off the cable into ECU.
Wire colors are subject to change. If wires have text labels - use labels to identify wire purpose.
Wiring harness for 4 and 6 cyl engines is unified. On a 4cyl engine you will not connect 5th and 6th cylinders.
The best spot to install the ECU is next to the stock unit. Stock ECU location:
- W124 - under the hood next to the battery
- W126 - front passenger legs compartment
Pull required wires from the harness. All wires should be connected in parallel to the original ones, otherwise it will be explicitly mentioned.
Connection to the 25pin ECU
- 1 - 12V
- 2 - GND
- 3 - IDLE (optional, read Idle Control section below)
- 5 - K-FULL
- 8 - Lambda - disconnect from the stock ECU
- 13 - K-IDLE
- 21 - CLT
- 25 - AN
Connect DH wire to the ground
Connection to the 55pin ECU
- 6 - GND
- 9 - 12V
- 13 - Lambda - disconnect from the stock ECU
- 16 - CLT
- 23 - IDLE (optional, read Idle Control section below)
- 27 - AN
- 46 - K-FULL
- 47 - K-IDLE
Connect DH wire to the ground
Stock Mercedes IAC controller is working fine, you can leave it as is. If you want to control IAC valve with Invent - disconnect the wire from the stock ECU and connect it to the IDLE wire.
Only 2-wire idle valve is supported. For 3-wire valve, external circuit is needed. For more information, look into additional info section at the end of the document.
Make sure to disconnect the lambda from the stock ECU to avoid interference.
If you don't have lambda sensor, or your sensor is malfunctioning, you should install universal Bosch sensor 0258986507 or 0258006537
- white wires - to the lambda heating connector, or to the fuel pump supply
- black - signal to the ECU
- gray - to the ECU ground
Connect the EXT wire to the gas supply valve, turn on the LPG mode by EXT input in the settings. Now the ECU will adapt to work on gas fuel.
If you have a carburetted LPG system - you do not need to cut the power of gasoline injectors. Check Turn off injection option and fuel will be cut by the signal from the EXT.
Connect EXT wire to the air conditioner clutch wire. It is used for maintaining idle RPM while air conditioner is operating.
Normally, you will use Bluetooth interface to connect to the ECU. In rare cases, BT connection is unreliable, so you can use K-Line instead.
To connect K-Line cable, you should prepare 3 wires:
Pinout of the K-Line cable:
Pinout of the car OBD2 connector
There are other wires, not mentioned in this manual. They are reserved for future use. Isolate and hide unused wires into the harness.
Stock ECU pinout
- 1 - Main relay power (Yel)
- 2 - Ground (Brn)
- 3 - Idle speed control valve control (Red/Wht)
- 4 -
- 5 - Full load throttle (Gry/Yel)
- 6 - Speed sensor (Grn/Yel)
- 7 - Ground/Return for cool. sensor (Brn/Wht)-Coolant sensor return for MY 1988 California version
- 8 - Oxygen sensor input (Grn)
- 9 - Fuel pump relay A/T (Grn/Blu)
- 10 - Electro-hydraulic actuator control(Brn/Blk)
- 11 - Altitude sensor (Blu/Red)
- 12 - Electro-hydraulic actuator supply (Brn/Blk)
- 13 - Closed throttle (Brn/Yel)
- 14 -
- 15 - Check engine indicator (Red/Grn)
- 16 - Ignition switch (Vio)
- 17 - Air flow sensor Input (Blu/Wht)
- 18 - Air flow sensor reference (Blu/Grn)
- 19 - A/C compressor (Blu/Yel)
- 20 - Ground (Brn/Red)
- 21 - Coolant temperature sensor (Grn/Red)
- 22 -
- 23 - Diagnostic
- 24 - Deceleration micro-switch input (Gry/wht)
- 25 - TD signal (Grn/Yell)
- 1 - Supply Battery voltage
- 2 - Purge valve
- 3 - 02 sensor heater voltage
- 4 - Idle speed control valve (+)
- 5 - Intake Air temperature sensor
- 6 - Chassis ground
- 7 - Impulse readout, malfunction memory
- 8 -
- 9 - Supply voltage
- 10 - Deceleration fuel shut-off microswitch
- 11 - Start signal
- 12 -
- 13 - 02 sensor signal
- 14 - Intake air temperature sensor
- 15 -
- 16 - Coolant temperature sensor
- 17 -
- 18 - Diagnostic signal 02 sensor heater
- 19 - Ground ECU
- 20 - Start valve activation
- 21 -
- 22 -
- 23 - Idle speed control Valve (-)
- 24 - Check engine warning lamp
- 25 -
- 26 - Data exchange with EZL ECU
- 27 - RPM signal
- 28 - Selector lever position
- 29 - Speed signal
- 30 - Lambda output, on/off ratio
- 31 - Air flow sensor supply voltage
- 32 - 02 sensor wire shielding
- 33 -
- 34 - Air flow sensor ground
- 35 - Ground
- 36 -
- 37 - Electro hydraulic actuator (+)
- 38 - EGR valve
- 39 - Transmission shift point control
- 40 -
- 41 - Supply voltage
- 42 - Air pump control signal
- 43 -
- 44 -
- 45 - A/C compressor engagement signal
- 46 - Full load throttle signal
- 47 - Closed throttle signal
- 48 -
- 49 -
- 50 -
- 51 -
- 52 - Air flow sensor input signal
- 53 -
- 54 -
- 55 - Electro hydraulic actuator (-)
MAP sensor pinout
Invent Jetronic ECU pinout
View at the ECU connector
|B||+12V||CLT||TPS||AN||KLINE||EMUL||IDLE SW||FULL SW|
(*) - АС input is available starting from ECU version 2.3
3-wire IAC valve
It has two windings - one for opening and the other for closing.
To connect this valve, an external circuit is required. A MOSFET with a current of >5A and a voltage of >55V is used.
The dotted line indicates the IAC.
- MAP - absolute pressure sensor
- TPS - throttle position sensor
- IAT - sensor air temperature
- CLT - coolant temperature sensor
- DH - Hall sensor
- AFS - airflow sensor