MicroSquirt.com read only forum (Jan.15,2018)

I have begun the tuning process. I have run several datalogs and I am confused about what I am seeing.

My understanding is that the low kPa values indicate low vacuum and higher kPa values indicate more or higher vacuum. The fuel Map layout seems to indicate just the reverse. Also so does my data logs. When I have a low TPS value I have a low kPa. Example: TPS of 1 to 5 gives a MAP kPa value in the 40 range. TPS in the 20 range under acceleration gives a MAP of Kpa in the 70's.

Where am I wrong?

Thanks,

Bill

wmahaffey wrote:I have begun the tuning process. I have run several datalogs and I am confused about what I am seeing.

My understanding is that the low kPa values indicate low vacuum and higher kPa values indicate more or higher vacuum. The fuel Map layout seems to indicate just the reverse. Also so does my data logs. When I have a low TPS value I have a low kPa. Example: TPS of 1 to 5 gives a MAP kPa value in the 40 range. TPS in the 20 range under acceleration gives a MAP of Kpa in the 70's.

Where am I wrong?

Thanks,

Bill

You got it a little backawards.. The vacuum levels reported are in KPA and are in ABSOLUTE units. , so 0 kpa = perfect vacuum and 100kpa = atmospheric pressure (well pretty damn close) So low kpa values are considered "high vacuum" i.e. 20" or mercury or more, and high kpa values are LOW vacuum (or closer to 0" of mercury)

Values over 100 kpa indicated boost (pressure) So at idle your KPA values should be fairly low and when you open the throttle kpa values should drop as engine load is increased (essentially speaking).

-- David

djandruczyk wrote: when you open the throttle kpa values should drop as engine load is increased (essentially speaking).

I think this is a typo. kpa follows load. When you open the throttle the kpa increases.

James

Thanks,

Bill