Forum » Practical Reflash Tuning » Speed Density on Ecutek

# Speed Density on Ecutek

### Tech Articles

Discussion and questions related to the course Practical Reflash Tuning

= Resolved threads

What information do I use to make changes on the VE table for Ecutek? Is there a formula? How I read the log file to make changes? What information from the log file do I use?

Andre Simon anything on this?

Keen for info on this also

At this point the EcuTek SD system is something I've only spent limited time testing. On an ECU that can't be tuned live, tuning the VE table can be quite time consuming, however it's still a relatively simple process to perform.

The SD system replaces the output of the MAF sensor with a calculated mass airflow in g/second. This is used as normal for the rest of the ECUs calculations for fuel and ignition. Essentially what we now need to do is make adjustments to the VE table if the measured AFR doesn't match the commanded AFR. If for example the AFR at 1.2 bar and 5200 rpm was 12.0, our target was 12.5 and we had a VE value of 101.8%, we can make a correction to get our AFR to match our target.

In this case our measured AFR is 12.0 and our desired AFR is 12.5 so the correction factor we need to use is 12.0/12.5 = 0.96. We can nnow multiply the value in the VE table to correct the error - In this case 101.8 * 0.96 = 97.7%.

Often we find that the MAF sensor is actually able to do a really good job of measuring mass airflow accurately at idle, cruise and low load. It's also very quick and easy (comparatively) to adjust the MAF scaling to get it right, vs adjusting every cell in a large 3D VE table. On the other hand when we add boost, it's easy to exceed the MAF sensor's measurement range and find that the engine goes lean and runs more timing than we'd like. This is where EcuTek's hybrid system comes in. Using this system we can utilise the MAF sensor for the majority of our tuning and then swap to SD only when we need to - Normally under boost where we are in danger of exceeding the MAF sensor's resolution.

That's the 2 minute over view. Hit me with some more specific questions and I'll see what I can do to help :)

I'll also add that you can speed up the SD tuning process greatly by using MegaLogViewer to analyse your log files rather than trying to do this inside the EcuTek software. The reason is that you can set up a histogram of AFR error vs load and rpm where you can replicate the break points in your VE table. Drive the car smoothly and access as many zones as possible as many times as possible and you'll build up an error histogram that you can use to correct the VE table. Provided your air temp correction is on point and you aren't inducing transient enrichment you can dial in this table in 2-3 attempts. Beats pouring over long log files in my opinion.

Hi Andre

Is using corrections within Megalog viewer explained somewhere please ?

I understand the principle when you're targeting the same across the entire table but not sure how to get an error value from the different target in different cells ?

Thanks