I'm trying to get into tuning. I figured that I would start by learning what all of the guage readings mean. I spent a few hours researching it all. Maybe, it will help others too. Feel free to add any information or correct me where I'm wrong:

AIT
This is air intake temperature or outside air temperature for the most part.

AIT2
This is the temperature of the air after passing and supercharger and being cooled. Ideally, it should be below 140f.

MAF Frequency (volume)
This is the CFM at least directly relates to it... So, this is the air volume passing through the MAF. It basically is a factor in yielding the lb/min? Does it have any direct use since lb/min is already given?

MAF lb/min (Density)
This is then the density in relation to the volume? It gives an idea of how much density in relation to AIT and other conditions? I have read that hp = (lb/m * 10).

With the hp factor above with lb/min. (lb/m * 10 / 5) = ideal injector lb/h.

(MAF lb/min) : (Injector lb/h / 60) | that is estimated A/F ratio too right?

Pulse Width
This is how many ms the injectors are spraying per cycle? This, from what I understand, is not feedback but only showing what is sent; so, it doesn't show errors. Ideally, you want values that are steady with no sharp changes.

So, this lets lets you know mainly the relation to the duty cycle. RPM/60 = RPS | (RPS inverted to ms * 2) = max duty reading | pulse ms / max ms = duty cycle percent? Also then, duty cycle percent * injector lb/h give actual fuel usage and more exact A/F?

Long/Short Term Fuel Trim
These relate directly to those A/F estimates from the last few readings. The trims are attempting to balance to ratio. Long term is the charted values of compensation over multiple cycles. Short term is the current set of cycles. Short + long = total correction max correction = 25% ideally 0-5%... If the above formulas are correct and lining up, then this shows an error with the injectors or air flow; otherwise, it signals that the above need closer attention.

O2 Sensor Voltage
0-0.45 = lean: 0.46-0.54=ideal: 0.55-0.9 = rich… Basically, 10 + (value * 10) = A/F ratio.

Manifold PSI
Simply, it is the inlet pressure in relation to a vacuum. Positive pressure is air being drawn in. Negative is air being forced out/balanced. I believe it is way more complicated than that though. There was so much documentation on it that I still have to read.

Supercharger Inlet Pressure
I can’t find any info on this.

Ignition Advance
Spark point in degrees prior to pistons full raised position. Too much = detonation or knock. Too little = loss of power.

Knock Retard
This is the degree of advance being removed due to knock. 0.0 is ideal. If it does show up, then the more boost/pressure (at the specific moment) the more potential damage.

P.S. This is my attempt to learn. It is not meant as me expressing that I know anything, so please try to view it that way.

 

a simple way to explain manifold pressure, as this one seems to be trouble for you, is the difference of pressure in the manifold vs outside the manifold. lets say your at sea level, where atmospheric pressure is a little under 15PSIa (absolute)if your running -3 in vacuum, then the manifold has 12PSIa of air inside with your 15PSIa of air outside. this is causing the gauge to read -3PSI (this is known as gauge pressure)

 

Nice, keep it updated with some details.

later