The Transient Throttle tables should be set up after the fuel and maps are correctly tuned for steady load running. Attempting to smooth out engine transients before the fuel maps have been optimised for steady state running may become confusing. Also ensure that you have tuned your injection angles for optimum response without any Transient Throttle Enrichment.

The Transient Throttle Enrichment setup allows the tuning of:

  • Enrichment Sensitivity - How much enrichment is needed for a given RPM & Throttle position

  • Percentage Async - The balance between Asynchronous and Synchronous enrichment over RPM

  • Percentage Enrichment - How much enrichment is needed for a given TPS change, known as Delta Load

  • Coolant Temp Correction - The amount of extra enrichment vs. coolant temperature

  • Enrichment Decay Rate - The speed at which the synchronous enrichment decays

Before You Begin Tuning:

Ensure that the engine is up to normal operating temperature. Leave all the settings at their default values. Leave all tables at their default values except for Percentage Enrichment, which should have all cells set to 100%.

Tuning Enrichment Sensitivity

The Enrichment Sensitivity table defines the amount of enrichment for large throttle changes. So while the engine is idling, open the throttle as sudden and quick;y as possible, with movements as large as possible. You do not need to hold the throttle down for any period of time, in order to minimise RPM and reduce stress on the engine.

Display the Transient Throttle Delta Load channel on a display or gauge to determine the magnitude of maximum Delta Load that you can achieve and note this value, as you will use this when tuning Percentage Enrichment.

Adjust the cells in the RPM band closest to your idle speed. The default table begins at 1000 RPM.

The Transient Throttle Load Source axis is the throttle position that you begin your throttle opening from. When tuning the response from idle, you will be opening the throttle from fully closed, or the 0% position. You may not be able to tune all the cells in this RPM row since you may not be able to hold near 1000 RPM with 10% throttle before performing your transient throttle opening.

Adjust these cells until the best throttle response is achieved.

Repeat for each RPM row and starting throttle position to fill out the table.

Tuning Percentage Async

At low engine speeds, a high amount of asynchronous enrichment usually helps with engine responsiveness. As engine speeds increase, the amount of asynchronous will need to be reduced to better distribute the enrichment. Adjust these for best throttle response across all engine speeds. You will typically only need to vary the Percentage Async across the lower half of your engine operating range.

Tuning Percentage Enrichment

The Percentage Enrichment table characterises the reduced amount of enrichment required for part throttle movements. The Enrichment Sensitivity table above is tuned for the fastest and largest throttle changes (Delta Load) that you expect to use.

The Percentage Enrichment table determines what fraction of that amount of enrichment is required when you move the throttle more slowly, or only make small changes in throttle. The slower throttle changes or smaller throttle changes, results in a smaller Delta Load.

To tune this table, set the far right hand column (Delta Load axis value - seen to be 25% below), as the largest Delta Load value achieved when tuning the Enrichment Sensitivity table.

The table value should already be set to 100%. If not, set the table value to 100%. In the example below, the largest Transient Throttle Delta Load that was achieved was 25%. With this table set to all 100%, the partial throttle openings will be too rich. Now vary the throttle opening speeds and throttle opening amount to achieve Transient Throttle Delta Load values less than the maximum, and adjust each cell in the table to achieve the best throttle response. In the example below, when Transient Throttle Delta Load is 10%, then 80% of the enrichment of a full speed, full throttle hit will be used.

Tuning Enrichment Decay Rate

Increase or decrease the Enrichment decay rate to shape the duration of the enrichment period. If the enrichment lasts for too long, then you need to increase the value in this table. If the enrichment does not last long enough, then decrease the values in this table.

The decay rate is difficult to tune without some form of exhaust gas oxygen meter. If you have access to an exhaust gas oxygen meter, then you may wish to use this to assist in tuning this table.

Tuning Coolant Temp Correction

To tune this table, the engine must be started cold. An engine changes temperature rapidly when started from cold, so be prepared with with laptop online and read to tune before starting the engine and beginning to tune this table.

Start the engine and check the cold throttle response. Adjust the enrichment for best throttle response across the coolant temperature while the engine is warming up.

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