2007 GT500 throttle "oscillation"?

[Pekka_Perkeles]

This is a 2007 Mustang GT500. Only mods are FRPP 2x65 mm TB and 129mm CAI.

Now, at very low throttle opening there is light bucking and timing is also changing 5...7 degrees at the same time.

Simultanously Spark source is changing between Base/MBT and Torque control.

Also, Torque source is changing between Driver demand and Oscillation.

I wonder what this oscillation is? Somehow related to a bigger than stock TB?

Tune and log attached.

48 sytk? nypytt??.hpl

46 vakiodd ja per?v?litys.hpt

[Pekka_Perkeles]

I think I found it:

"OSCMOD stands for oscillation modulation. Engine torque is modulated via spark advance as a function of the rate of change of
rpm in order to stabilize oscillations in rpm. This is a derivative control method and functions as a dashpot. This correction
may be useful during closed throttle or negative crowd decelerations to control shuffle. It can also be used without
interference with feedback spark."

I have now set it to a 1.0 so it should be disabled now. Will try it next weekend.

OSCMOD.jpg

[Thatwhite5.0]

The cause of your throttle oscillation is your throttle body model. Etc area and throttle angle predictive. The two tables are miscaclculating, throwing the air model off.

Look for the correct TB data. You should be able to use the twin 67 throttle body model as is or adjust higher throttle angle/ etc area columns.
That data look to be for a larger monoblade.

[Pekka_Perkeles]

Well, that's interesting.

I found this thread:

https://forum.hptuners.com/showthrea...0-2016-2-3-vmp

And from that thread this pic:

Twin67mm Specs.png

Since HPTuners has nice ETC Effective area calculator, I only manually copied the Predicted Throttle Angle from the pic and then used calculator for the Effective Area.

I was very surprised that the final values were far from the pic...

51 67mm tb.hpt

[Pekka_Perkeles]

The cause of your throttle oscillation is your throttle body model. Etc area and throttle angle predictive. The two tables are miscaclculating, throwing the air model off.

Look for the correct TB data. You should be able to use the twin 67 throttle body model as is or adjust higher throttle angle/ etc area columns.

That did the the trick! No more bucking.

Thank you.