Why throttle based fueling? Timing calculation explanation?

Hey guys,

I'm new to VCM but familiar with tuning aftermarket ecus, Haltech, MS, etc. I have some questions about some key differences in the Falcon PCM.

Can anyone explain why the Falcon PCM uses throttle based fueling instead of load?

Is there any information about how ignition advance is calculated or can someone explain it? As I understand it, the MBT table represents the theoretical best timing and is also used as a max advance limit. Most people seem to edit the BK table to alter timing but do these numbers represent actual degrees?

Do the values in the spark adder such as lambda and IAT represent +/- absolute degrees or again, just part of a calculation?

If someone can shine some light on any of this I would be most appreciative.

Thanks in advanced,

Tim

Quote:

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Originally Posted by timwds

Hey guys,

I'm new to VCM but familiar with tuning aftermarket ecus, Haltech, MS, etc. I have some questions about some key differences in the Falcon PCM.

Can anyone explain why the Falcon PCM uses throttle based fueling instead of load?

Is there any information about how ignition advance is calculated or can someone explain it? As I understand it, the MBT table represents the theoretical best timing and is also used as a max advance limit. Most people seem to edit the BK table to alter timing but do these numbers represent actual degrees?

Do the values in the spark adder such as lambda and IAT represent +/- absolute degrees or again, just part of a calculation?

If someone can shine some light on any of this I would be most appreciative.

Thanks in advanced,

Tim

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Some Fords use TP , some use Load for the commanded fueling in Open Loop.

Borderline Knock is the best area to adjust the timing. The PCM always uses the lowest spark calculation. No reason to change MBT unless there have been real changes to the engine that would actually change MBT. The numbers are in degrees.

There are two IAT tables, and two ECT tables. The one with the large timing values is in actual degrees. It gets multiplied by another table that has very small values, to come up with the amount to retard.

Thanks Eric!

This makes a lot more sense now. I've made a spreadsheet to assist tuning, let me know if I'm wrong.
NOTE: This does not take into account of any spark corrections(lambda, IAT).

Attachment 44869

The load is not hard coded to 1.6 and can be upped to 2.4 ( limit of map sensor ) after that your flying blind

Also just because u request a degree does not always mean ull achieve it and timing logs will show this so keep the gradience ( incline/decline ) to a smoothish level to at least get as close as possible to requested degree

Thanks Jet,

Soooo... How does one increase the load scale? :rolleyes:

EDIT: I imagine the current values will need to be interpolated to fit.

Yes as u would not ( in most cases ) want to see those degrees for increased load points

Click on the axis relative to what u want to change ( this goes for nearly anything on hp ) but only stuff with it if your logging is going to back up what u cant see as u may venture into territory that can do damage quickly

That's awesome, thanks again Jet. I'm going to need more go fast bits before I can even think about changing those :P

If we change the load values in the spark tables, we need to make adjustments to the Load with Failed MAF table? Is this table something we should even be adjusting?

2.4 is the upper limit of the APS PCM whereas the ABU and ASU will hit 2.7. Difference is due to the speed density calibrations.