Wheelslip on DDA40X

[Approach_Medium]

Hi;
I was playing around with a CSX DDA40X.
Single unit pulling 3094 t train. About 2 seconds after I move the throttle to 1st notch, I get wheelslip.
I found that "pumping" the throttoe to 1st notch, then back to 0 once or twice as the train is starting will eliminate the slip.
I then added another DDA40X, and had the same results.
Same also when the 2nd loco was in the rear.

The grade on this track is down, 0.12.

Compare this to two CSX C30-7's (by Norfolksouthern37), and I do not get any wheelslip with those locos pulling the same train.

Are the physics on the DDA40X off, or is this "normal" for high HP locos?

 

[nicky9499]

Wheelslip on a downhill?

 

[Approach_Medium]

I'll have to check the grade on the track where the rest of the train is. It is possible that it's up-grade most of the way, then down where the locos are.
Or, maybe the loco's physics are off.

I did check that I was releasing the brakes fully before moving the throttle up.

Edit: These are the DDA40X units by phil_c.
I tried the same consist on a new route, just track, no grade at all, and results are the same. There is definitely something wrong with physics for this loco.