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How does E-Tunez know how to tune my car without a dyno?

In the days of carbureted engines, tuning on a dyno was a necessity. A dyno graph was the only form of feedback, aside from the art of reading plugs, and listening to the tone of the exhaust.

Now adays, tuning a fuel injected vehicle has evolved from an art of the gear heads down to a science. It’s a battle of numbers, instead of a battle of sounds, colors and smells. For example we tune for 13.1 AFR, 54 psi of fuel pressure, and 27 degrees of WOT ignition advance as opposed to light brown spark plugs, a crisp exhaust note and no ping. The tuning process has evolved and we have learned that the result of good number’s, IS good colors (plugs), tones (exhaust) and no knock (ping) rather then vice versa.

There are many other forms of feedback available to the enthusiast. You have a large array of sensors that your vehicle uses to compensate for elevation changes, manufacturing variances, fuel condition, and driving habits, to name a few.

We can use these sensors combined with the FACTORY built-in Wide Band O2 sensor to tell how your car is running, and verify any changes made.

E-tuning your car will ensure that Short Term Fuel Trims (a measure of how close the car is running to “ideal”) are as near ideal or 0% as possible, it will confirm your AFR’s are within the target range (13.1 - 13.5 for the K20Z3), it will confirm that your map is free of errors (RPM indexing, VTEC fuel transitions) and it will tune your car FOR the way YOU drive it!

When you provide a datalog of your daily driving, we can see how the sensors are responding to your input, and your current location. When your car was produced, the manufacture did not know where it would be driven, who would be driving, and how you would be driving it. The manufacture did not know the quality of fuel you would use or the exact concentration of ethanol in that fuel. On top of that, every car of the same model and trim level leaving the factory had the SAME ECU mapping despite all of the above variables.

This left the difficult task of using one ECU mapping, for tens of thousand’s of different cars spread across the continent… IE the North American 8th Gen Civic Si. Honda didn’t know which part of map you would use every day, and they certainly did not take a car all over the globe to test in every real world scenario IE Colorado (elevated and dry), vs Miami (sea Level and Humid), vs Canadian Winters on the prairies... etc. All those factors affect the STFT or overall performance of the vehicle, and how long it will take to learn to correct itself.

When the STFT shows it is out (anything other then 0%), the car must “re-learn” how to get things right. This time that the car spends “re-learning” costs performance and mileage. When the fuel maps appear incorrect due to closed sensor production variance, location (air density, humidity), or modification, this re-learning will happen EVERY time you change the pedal position, or the vacuum in the manifold.

When we tune your car, we look at WHERE it is being used and HOW it is being used, and our tunes account for those conditions, along with conditions that were not accounted for at the factory, like sensor production variance… For example, not every Mass Air Pressure sensor is exactly the same, and the same can be said for every other sensor in the vehicle. When your car was brand new, it could typically run a +/-10% Short Term Fuel Trim… as you add modifications, un-tuned it will drift even further, unless your really lucky and happen to compensate in the other direction. Either way you won't know until its tuned and the numbers are analysed. Within the first 2 revisions we usually have the K20Z3 running within 5% of ideal, including all modifications… by revisions 3-5 we are typically within 1-3% of ideal, in all conditions measured. This results in a huge improvement in drivability, as seen in our feedback section. Just start and go... no bucking, or hesitation when cold... great performance from startup to shutdown, unlike a stock or similar baseline map.