5 Cycles of Corrections and Expanding Target AFR

 In this video, I go over in detail the typical cycles you will be performing to properly tune in your engine. I go through 5 cycles, starting with the Base tune you should have created, then by flashing the tune to your ECU, riding while recording log(s), copying these logs to your computer and then using Dynojet's Power Core Software Suite's C3 and Data Center modules to perform the corrections.  We repeat this sequence for 5 times in this tutorial.

This is part one of the fuel tuning. 

5 Cycles of Corrections and Expanding Target AFR (Part 1)

The very first log shows some strange excursions of the Long Term Fuel Trims.  We look at what is causing this.  This is all part of tuning your bike, you will find strange behavior from time to time, fortunately Dynojet has provided a very powerful tool with the Data Center so we can determine the root cause of the abnormal data.

Here is an example of the log we are discussion:

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This log has been zoomed into a section that did not look right.  The Short-term fuel trims go to zero, yet the long term fuel trims are showing activity.  The tuning equation will ignore this data so erroneous data does not corrupt the tune, however this is a good example of getting to the root cause of this.

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By changing the channels on the bottom graph to Primary Bit and Gear Position, you can see that the Primary Bit goes from its normal 1 state (active) to the in-active state of 0.  Remember from previous discussion that whenever the Primary Bit is not 1, then something abnormal is going on.  In this cause we are in deceleration mode and the primary timing table is not being used.  Timing Tables 3 & 4 are active.

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Verifying that Primary Bit is zero

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Changing the lower graph to display Engine Speed and Primary Bit illustrates the deceleration clearly.

Going over to the post: Anatomy of a tune, here are the notes for timing:

If Primary Timing Active bit is equal to 1 (usual case when accelerating):

base timing target = Ignition Timing 1 Primary table minus knock retard (If vehicle equipped with knock sensor).

If Primary Timing Active bit is equal to 0, the ECU follows the following logic:

a = Ignition Timing table 2 plus Timing Table 2 Modifier by AFR, minus value from Ignition Timing 2 Scaling Array

b = Ignition Timing 1 Primary table minus Knock Control (If vehicle equipped with knock sensor).

c = Ignition Timing table 3 (or timing table 4 in rear cases)

d = minimum value from a and b

Base timing target = max value from c and d

After the base value is calculated, any temperature, tip-in, and/or per cylinder compensations are applied.

Final ignition timing targets are capped to a range of -36 to 54 degrees.

So in summary, the timing should always be the Ignition Timing 1 (Primary) unless we are at idle or decel.  You can view data bit in the log file titled "Primary Timing Active bit" to make sure the Ignition Timing 1 (Primary) table is active.