Invent Jetronic setup manual

Invent-Jetronic Commander overview

Initial setup

Connections check

Sensors setup

Injection calibration

Idle adjustment


Setting up VEZ ignition advance

Invent-Jetronic Commander overview

Initial setup

Set COM port number of your USB adapter and press ON

Commander will read all calibrations from ECU

If you see “commander version not corresponding to firmware version” warning - don’t change any calibrations! You should update firmware in ECU in order to proceed. Download firmware from our website.

Turn on autosave

Parameters - Firmware tab

Fill ECU name field. This name is used in log and calibration filenames. For example - enter your nick name.

In Description field you can enter any text you want. It will be stored in ECU.

Parameters - Main tab

Enter cylinder count

Enable TPS sensor if installed

Enable Phased injection if distributor is prepared.

Connections check

Idle and full load switches

Fully press and release throttle several times and check if appropriate lamps will lit for pressed and released pedal.

Press pedal gently, and check that Idle switch will turn off at the early beginning of pedal travel.


Enable test for each injector and listen. Injector will click approx. once a second. Check wiring if no sound produced.


Check if air and engine temperatures are displayed correctly.

Start engine and check manifold pressure. Pressure on idle should be around 30-45 kPa.

If pressure is 100 kPa - check vacuum hose connection

If pressure is 50-60 kPa - check vacuum hose, camshaft positioning, valves, ignition angle.

Sensors setup

Throttle position sensor (TPS)

If TPS is installed, you should calibrate it

Open Parameners - Sensors tab.

Press pedal gently, and check that TPS voltage increase linearly and smoothly according to pedal movement. Should be no dead zones, voltage decrease, harsh signal, etc. If you mentioned a problem - possible that sensor is out of operating angle. You should turn sensor case to fix the problem.

Release pedal. Enter sensor voltage into 0% field, but with small gap. Gap is needed to guarantee that TPS position will always set to 0% upon pedal release. For example, if sensor voltage is 0.352, you should set 0% to approx. 0.36. Then press pedal several times and check that TPS position will set to 0% on pedal release.

Fully press pedal. Enter sensor voltage into 100% field

Injection calibration

Don’t forget to connect vacuum to fuel pressure regulator.


Warm up motor.

Set normal idle RPM using manual positioning

Open Injection - AFR. Check that idle zone is set to 14.7 (see picture). If not - set it to 14.7.

Enable lambda control.

Clear adaptation.

Wait until lambda correction value start changing

We will adjust 2 parameters: Injection time multiplier and Light load correction

You should watch lambda correction digits. Big digit is fast correction, small digit is slow correction. Total correction = fast+slow.

correction > 0  =  lack of fuel  = increase calibration

correction < 0  =  too much fuel  = decrease calibration

Calibration procedure

  1. Motor is idling. Adjust Light load corr. to achieve near zero lambda corrections.
  2. Drive on road. Hold stable 2700-3000 RPM and 70-90 kPa pressure (see picture).  Adjust Injection time multiplier to achieve near zero lambda corrections.

  1. Repeat steps 1-2

lambda corrections will always float, especially at idle. It’s normal behavior.

Don’t forget to save your calibrations to file!

Idle adjustment

Minimal position

Minimal regulator position. Regulator can’t close below this position

Audi uses idle valve with emergency position. Valve is slightly opened at 0% to keep RPM in case of valve failure. Then, if you increase position, valve is fully closed. Approx. after 25-30% valve starts to open. So your minimal position for Audi valve should be not less than 25-30%.

  1. Warm up engine.
  2. Set RPM slightly below normal idle using Manual position. For example, if idle RPM is 750 - then set 650.
  3. Enter current idle position into Min position at 70C
  4. Repeat steps 2-3 at the morning, when engine temp. is 40-50C, and enter idle position value into Min position at 30C

If idle RPM is abovenormal, you should check if regulator is stuck at minimal position. If yes, you should adjust it lower.

Don’t forget to save your calibrations to file!


Engine loses power when Full Load Switch is engaged

Set proper VEZ ignition advance (see instructions below)

Can’t set RPM below 800-900 using manual idle position

Search for leakages in intake manifold. Check hoses, idle valve, injectors inserts, injectors ventilation, throttle assembly.

High fuel consumption

Check lambda sensor health, check fuel line for leakage.

Setting up VEZ ignition advance

You should have stroboscope to proceed

  1. Turn on service mode by closing diagnistic pins. Check that stroboscope mark is standing still. If not - repeat closing pins. (on some cars one closing is enough, on some you should close pins 3 times)
  2. Set ignition advance 15-17 degrees