This setting is developed to use a MAP signal on multiple throttle body engines. The problem with them is there is no intake plenum where the vacuum could be measured. The vacuum signal only makes a spike when the valve opens. This spike is also there only once in two RPM’s. This makes it important to read the signal on crank degrees when the vacuum signal is present. This setting is only available for gear type triggers as low as 12 teeth.

Single
Most engines have one throttle and an intake plenum where a map sensor is used. The map signal is read 2 or 3 times per revolution. It makes for a fast vacuum signal response. The map teeth can still be adjusted here as there is a small amount of pulsation in the intake plenum.

Multiple
To use this method a crank gear of min 12 teeth is required. The MAP sensor is only connected to cylinder 1 or the cylinder that shares the crank degrees on movement. With this feature the MAP sensor is read once per two RPM’s when the vacuum signal is present. This makes for a slow response that may cause flat spots during blip. This however can be cured with the accelerator settings. One requirement is that the throttles are properly balanced as only one’s vacuum is measured. The map teeth setting here is very important. When the engine idles it is adjusted to read the best vacuum. The more teeth on the crank gear the finer adjustment could be made to find the sweet spot. This sweet spot on the vacuum signal is around 90° after TDC. For a 36-1 gear 90° would be 9 teeth.