Preparing for the Auto-calibration of an AEB-manufactured LPG System

AEB-manufactured LPG systems include the following brand names – AEB, Bigas, Emer, King, OMVL, Romano, Tartarini, Zavoli and possibly others too. This article assumes that the installation is complete and that you have the correct software on your PC and have made the connection to the LPG ECU.

From the Main Menu select Vehicle Configuration. Start on the Change-over screen and set the following parameters.

  1. Fuel Type – LPG
  2. Injectors – select the option that matches your LPG injectors
  3. Type of Revolution Signal – if you have not connected the brown wire, remove the tick from the box. If you have connected the brown wire (we recommend this) tick the box and select Standard from the dropdown list.
  4. Ignition Type – select One Coil if you have one coil per cylinder, otherwise select one of the other options. At this point it is not important which option is selected.
  5. Inj. – most engines have a sequential injector firing pattern, so select Sequential. If your engine fires all petrol injectors at the same time, select Full-Group. MJ-Sequential is for engines that fire each injector multiple times per cycle and is quite rare.
  6. Reducer – enter the operating pressure (when running on gas) of the reducer (this may be fixed or variable.
  7. Cylinders – enter the number of cylinders
  8. Valvetronic – tick the box if your engine is of this type (e.g. some BMW engine)
  9. Type of Change-over – In-acceleration if you have an automatic gearbox, In-deceleration for a manual box.
  10. Leave all other fields as standard for now.

On the Lambda screen, set the following parameters.

  1. Number of Banks – for an in-line 3 or 4-cylinder engine select 1. For a boxer engine select 2. For more than 4 cylinders, select 2 banks.
  2. Type of Pre-Catalytic Oxygen Sensor – select the type that matches your engine.
  3. Oxygen Sensor 1 – we recommend that the purple wire is connected to the pre-cat oxygen sensor signal wire of bank 1. Set this parameter to match your installation.
  4. Oxygen Sensor 2 – we recommend that the purple/black wire is connected to the pre-cat oxygen sensor signal wire of bank 2. Set this parameter to match your installation.

On the Sensors screen, set the following parameters.

  1. Type of Gas Level Sensor – set this to AEB or 0-90 Ohm to match your installation.
  2. Tank Solenoid with Dedicated Wire – tick this box if you have used the blue/white wire to power the tank solenoid. Clear the box if you have used the blue wire.

Leave all other parameters set to the default settings for now.

Turn off the ignition and wait for the lights on the change-over switch to go out, then re-start the engine. This procedure is referred to below as RESTART.

Look at the Vehicle Configuration – Change-over screen. With the engine running on petrol you should see the following readings at the bottom of the screen.

  1. Revs – this should match the number on the rev. counter. If you do not have a rev. counter, expect 700-900 rpm at tick-over. If the software shows half or double what it should be, change the Ignition Type to a different value. RESTART and re-check the revs. The value must be correct for auto-calibration to work.
  2. T. Reduc – reducer/vaporiser temperature – this should be the same as engine temperature – about 80°C. It must be at least 50°C for auto-calibration to work.
  3. T. Gas – gas temperature – usually measured at the rail and usually around 40°C. It may show a low temperature if the engine bay is cold and no gas is flowing through the rail. You may need to close the bonnet to warm it up. If T Gas is higher than T Reduc, the sensor wires are probably switched so fix this. T Gas must be at least 25°C for auto-calibration to work.
  4. Tinj. Gas – Gas injector timing – should be zero when running on petrol.
  5. Tinj Petrol – Petrol injector timing – should be between 1.5 and 4ms. If this is not showing, the wiring of the petrol injectors is wrong. This must be fixed.
  6. Press Gas – gas pressure – this is usually 1.0-2.0 bar when running on petrol. It will drop to an operating level when on gas. If this is out of range, the pipes to the pressure sensor are wrong or the electrical connection is wrong. Fix it.
  7. MAP – Manifold Absolute Pressure – this is usually 0.2-0.4 bar at tick-over. Outside this range implicates the pipe-work again. Fix it.
  8. Lambda 1 – if connected should show a fluctuating voltage within its operating range.
  9. Lambda 2 – if connected should show a fluctuating voltage within its operating range.

Work through the above checks and resolve any issues before proceeding.

Go to the main Menu and select Diagnosis or Injector Check.

There may be some diagnostic messages at the top of the screen. Make a note of them, then click Reset Errors. Put a tick in the Enable Diagnosis box. RESTART and see if any diagnostic messages appear. If they do, check the wiring and/or piping to fix the error.

Check Petrol Injectors Signal Diagnosis. You should see green boxes and petrol injector timings for every cylinder. If not, you have cut the injector positive wire instead of the negative – change it.

Work through the above checks and resolve any issues before proceeding.

Make sure that the engine has reached its change-over temperature and see if it will switch to gas. If it does, continue with the injector check below, otherwise run Auto-calibrate and return to the injector check.

Go to the main Menu and select Diagnosis or Injector Check.

With the engine running on gas, switch each individual cylinder from gas to petrol using the Gas Injectors Cut-out box. Each time you switch a cylinder, listen carefully to the engine – there should be virtually no change in the running. If switching one cylinder causes a problem, switch it back to gas and move to the next cylinder. Note which cylinders have caused problems. Such problems are caused by shutting off all fuel to a cylinder or supplying 2 lots of fuel to a cylinder. The 2 possible causes are wrong wiring of a petrol injector cut-in loom (the solid coloured wire should be connected to the injectornegative wire and the wire with a black trace should be connected to the wire returning to the petrol ECU), or incorrect pairing of petrol and gas injectors. If the wiring is wrong, fix it and re-run this test. If you have a 5-8-cylinder engine, check that the banks are not switched. The petrol injector intercept loom of bank 2 should have a red band round it and the bank 2 gas injector loom should feed gas injectors E, F, G and H. If you have changed the wiring, re-run this test.

If the wiring is correct it must be a pairing problem. Start with the engine running on gas and all gas injectors switched on. Switch off one of the problem injectors. Switch off another problem injector to see if it cures the problem. If not switch it back on and do the same with the next problem injector. You should find a pair that fixes the problem when both are off. Swap the plugs on the 2 gas injectors and then turn them on again. You should now be able to switch them off with virtually no change in the running. Work through the above checks until you can switch off any of the gas injectors without affecting the running.

Go to the main Menu and select Vehicle Configuration, Chang-over. With the engine running on gas, check the Tinj.Gas. For slower injectors this should be around 4ms and for quick injectors around 3ms. If Tinj. Gas is lower than this, then the gas pressure is too high or the rail nozzle size is too big, and vice versa. Valtek type 30 and 34 rail nozzles need to be drilled to the correct size. Bigas rails need the correct size of jet fitted. Check that the nozzle size is correct for the engine by referring to the sizing charts for the rail. If you change the nozzles size, re-run this test.

Go to the main Menu and select Auto-calibration. Click Start Calibration and follow the instructions on the screen. This should take about a minute. If the engine struggles to run and/or calibration does not complete, it usually means that you have pipes or wires crossed. You need to go through all of the above tests again to identify the problem.

If auto-calibration completes successfully, save the configuration before moving on to fine tuning. Give the set-up a name that includes the registration number, odometer reading and the gas pressure (e.g. p130 for 1.30bar). Any calibration is valid only at the calibration pressure.

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