How is engine load calculated?

[Mirage1]

On my 2G with a Pocketlogger I am logging 18-20% load at idle. The car is basically stock. Does this mean anything and if so, how is the engine load calculated? I tried a search and came up with nothing.

Thanks!

 

[taylorspl]

There is a post somewhere in this thread about load at idle. I have no idea how its calculated I just thought you might want to read this.

 

[Mirage1]

Thanks Taylor. A local SW DSM member too!

I read that thread earlier. But I'm still interested in how engine load is calculated. I want to get as much info as possible. Most likely my problem is retarded timing. Which is one of the symptoms I'm still troubleshooting. But it is on a 2G 7-bolt. The others in that post seem to all have 6-bolts. Also, I have already verified that the cam timing is dead on.

I did lower the boost down to 13-14psi and it seems a little more stable. So I am thinking that I was running to much boost for my setup. I will test it out more tomorrow and get some more logs.

 

[taylorspl]

The basic injector driving time, also called the activation duration or the injector pulse width (IPW), is determined in many steps. First, engine load is calculated using just the air flow sensor and engine speed for closed-loop operation, and the air flow sensor, engine speed and intake air temperature and barometric pressure for open-loop operation. The volume air flow divided by the engine speed determines the engine load factor, called A/N (and displayed on the factory "boost gauge"). As volume air flow increases, injection duration increases. As engine speed increases, injector frequency increases. Next, the ECU selects closed- or open-loop mode based on throttle opening, engine speed, vehicle speed, and fuel trim and air flow maps. Then corrections to the target fuel volume are adjusted based on the following and an injector pulse width calculated: engine speed, engine coolant temperature, throttle position, intake air temperature, barometric pressure, detonation sensor, fuel injector scaling, and battery voltage (deadtime compensation). The flow chart below summarizes the interaction of components.

This is taken from this page. There is a dsm ecu yahoo list and I think theres a forum out there somewhere too. If you keep looking you'll find more I'm sure.