can some one explain to me what the MAP is. is it mass air pressure, if so how does that affect the spark advance. i have heard that there is still more power to be had by advancing the timing. but how do you know when to much is to much (what sensors do i need to watch while doing it. and how do they relate to each other.

and what is the knock count, i know what knock retatrd is but what exactly is the knock count. is it the amount of times that the knock sensor picks up a knock and then shows up as knock retard. just a little uncler on this area.

any links that will help explain scanning to me and all its aspects, and sensor.

thanks agian.

this may be common sence to some but i will never know unless i ask.

 

This is a good place to start.

 

Have you checked out my online "Scanner" writeup?

Scanner Writeup

MAP is "manifold absolute pressure". This is the pressure in the intake manifold, reference to "absolute pressure". In the absolute system, atmospheric pressure is about 14.7psi = 101kPa = 29.9"Hg. The MAP sensor will tell you the atmospheric pressure, or "BAR" when you start the engine.

If you have atmospheric pressure outside the manifold, there will be a pressure "loss" as the air moves through the intake, TB, manifold, etc. At WOT, MAP approaches close to atmospheric pressure. At idle, there is a huge pressure loss, because the throttle blades are closed. MAP in a stock cam engine will drop to 35kPa = 9.5"Hg.

The PCM uses MAP as a measure of engine "load". When MAP is low, at idle or at low rpm, the load on the engine is "low". When MAP is high, as at WOT, the load on the engine is "high".

The spark timing is set in a table with RPM on one axis and MAP (engine load) on the other. The PCM alters timing in response to engine load, based on MAP and RPM. To advance timing, you need to alter the table in the PCM. I don't think there is a lot to be gained by advancing timing compared to the factgory settings, which are already fairly aggressive.

Knock count is a cumulative field, increasing as knock signals are received from the sensor. Not sure how it realtes to retard, although you generally don't getr any retard if there is no change in knock count. Eventually, the number will reach the limit of the field, and reset to "0".

 

i know i need to learn about alot of things before i start tunning my own car after i get the cam put in. so heres another ? for you. is there a site that will tell you the basics of programing. maybe tell you how to get started. hints and tips stuff like that.