With the engine now running, allow it to reach normal operating temperature - typically 70-95*C. This is to ensure no warm-up corrections are taking place, which can be verified by looking at the DROs under the ‘Environmental’ section of the tree view - they should all typically say zero.


You will need a wideband lambda system to correctly tune the VE table - if you do not have one, then you may cause damage to your engine if you cannot verify correct fuelling - it is best at this point to either purchase one, or take the car to one of our agents to have the engine professionally tuned. 


With tuners all over the UK, and more and more being added across Europe and worldwide, car transport will always be cheaper than a new engine.


You should also check that lambda control is currently in-active, by disabling Lambda under the Lambda Settings driver (Lambda Control>Lambda Settings) by changing ‘Type’ to ‘Disabled’. Note that the WBO2 Curr. AFR will still display an AFR if you have correctly wired your wideband O2 controller to the ECU.


You then ensure your target AFR table is set correctly (Lambda Control>Target AFR Table). A typical table for a turbocharged Mazda MX-5 engine is shown below:



We won't go into detail about the perfect AFRs to run in different areas of the map, as it varies from engine to engine, however, typically:

●        As load increases, the engine mixture should be richened. Typically, around 13:1 AFR on naturally aspirated engines at high load, and richer still (11-12:1 AFR) on forced induction engines as you enter boost.

●        Idle should be around 14-14.7:1 AFR

●        High RPM, low load should aim for 15:1 AFR for a ‘lean cruise’ to increase MPG.


We won't go into the fine art of tuning here, as that is very much something that should be ‘known’ to get the best from the ECU, however, we will cover the basics. (Refer to keys/functions of the 3D table views. for possible interaction keys.)


As per the fuelling model at the start of this guide, we know we need to get the right amount of fuel in there for optimum power and also safety at any given load and engine speed. Load can be derived either from throttle position (when running a naturally aspirated engine) or from manifold pressure when running a ‘charged’ engine.


It is worth noting that a VE table will often ‘look’ like a torque curve - where the most VE is, is the same point where the most fuel can go in, and the more fuel that is burnt CORRECTLY means the most torque is produced at that point.


Here is a turbocharged MX-5 VE table, we can see that more power is produced as manifold pressure increases (i.e the more open the throttle and the more boost we have), and also that peak power is around 5,500-6,000RPM, as shown by the red areas of the plot.

If you are used to older pulse-width based ECUs then you will be compensating in your main fuel table for the fact that a turbo charged engine requires rich (11-12:1 AFR) mixtures under boost, and leaner mixtures around cruise and idle.


With our VE based model, we only need to map the engines REAL VE as we have another table that takes care of what we would like the AFR to be (in terms of the maths behind converting a VE into fuelling, whilst taking consideration the required mixture ratio at that point in the engine's operating range), and that, is rightly named ‘Target AFR Table’ under the ‘lambda’ node:


So, we can see it is important to set the Target AFR Table FIRST, and then tune the VE table to reach these AFRs at each point - ultimately, reverse engineering the engines ability to pump air - or - its Volumetric Efficiency (VE).

If you were to change the cams, cylinder head design, exhaust etc, then you would effect the VE - correct for those changes in the VE table, and the engine will still make the target AFR you have specified. The reverse is true: If you map the VE of the engine correctly such that the AFRs match the target AFR table, then any-time later you could change the AFR table, perhaps going from 12.6 to 12.1 at a certain point, and the VE algorithm will modify the fuel pulse width accordingly to reach that AFR, accurately.


NOTE: If you are using closed loop wideband lambda control, it should be turned OFF when mapping, or else the ECU will trim the fuelling to reach the AFR set in the Target AFR Table. This could be used as a ‘cheat’ to map the engine - simply turn on closed loop wideband, and adjust the VE table live such that the ‘Fuel Lambda Trim’ is as close to zero as possible - if the closed loop wideband algorithm is trying to richen the mixture, then increase the VE number at that point, if trying to lean it, then reduce the VE at that point - a ‘man in the middle’ auto-tune algorithm….