AMP EFI MS3Pro - X-Tau Acceleration Enrichment; Puddling Factors; Time Factors

7.5 Accel Enrich 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
12. Once small, slow throttle movements are tuned, larger ones can be verified, as well as normal driving with
gear shifts.
13. Finally, try to quickly blip the throttle while free-revving. If response is slower than desired, a very small
amount of TPSdot or MAPdot acceleration enrichment may be re-enabled. Take care to only use it for high
TPSdot values and use very little. Just enough to get EAE to respond is all that is required.
The second set of EAE curves under the main ones are for use with dual fuel mode, as alternate fuels often
vaporize at different rates and need different tuning.
7.5.3 X-Tau acceleration enrichment
X-Tau is an alternate model based acceleration enrichment, with slightly different equations. This uses a number
called X to represent the percentage of fuel sticking to intake walls, and tau to represent the amount of time it
takes for the fuel that sticks to the walls to reach the cylinder. While EAE uses a load scalar curve, X-Tau uses two
separate, RPM based curves for acceleration and deceleration. The X-Tau algorithm uses the rate of change of
the MAP reading, not the absolute value of the MAP reading, to determine which of these two curves to use. At
steady MAP, it blends between the two.
7.5.3.1 Puddling Factors
This is the X term. There are two tables, one for acceleration and one for deceleration, which represent what
percent of the fuel puddles in the intake as a function of RPM. Note that in the way the X-Tau numbering works,
setting either curve to values above 48% can cause the fueling to oscillate, particularly at low RPM, unless you
use large tau values as well.
7.5.3.2 Time factors
This is the tau term. This number represents the time, in milliseconds, for the fuel to travel from the puddle to
the cylinders. Valid numbers are from 10 msec to 2500 msec. The closer the fuel puddle is to the intake port and
the faster the air is moving, the lower the number. A port injected engine with small intake runners and injectors
targeted on the intake valves will be on the low side of the scale. A throttle body injection intake will be on the high
side.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 198