what are the parameters used in the pacejika formula?

It is very important you take some time to understand those values, build yourself a small editor that is able to plot the curve generated by a set of parameters so you can understand how each one of them is affecting the curves.

I would suggest you to drop the pacejika aside for a moment and just use a linear force vs slip relation. Make sure everything works as expected then dive into more complex slip models. At the moment there are too many things that can go wrong in that code.

There is no reason to cut the slip ratio under 1. Actually most of the time the slip is very low, reaching a peak at around 0.2 .

Recode with a linear relationship and have the program print out a line per iteration with all the relevant torques, forces and velocities.

k.. it's getting more clear now..here are some mistakes:

ForceTraction = ForceDrive * ForcePacejka;

This should be something like :

ForceTraction = WheelLoad * ForcePacejka;

Remember, engine torque accelerate the wheel, this create slip and the slip accelerate the car.

To be correct, the pacejka "force" function should have a load as input:

public static float PacejkaLong(float slipRatio, float load);

And do the multiplication in there.

The load could be a static value calculated from the car's mass and the weight distribution or a dynamic one that takes into a account the weight shift (you should definitely do this one)

I also thing this:

TorqueTotal = TorqueDrive + TorqueTraction + TorqueBrake;

Should change into:

TorqueTotal = TorqueDrive - TorqueTraction + TorqueBrake;

Usually cars have a rpm limiter that will engage when the rpm go over a certain limit. This is usually working by cutting the electric power to the sparks, so the effect is instant (ie.. no detonation). With the RPM on the engine will produce a negative torque due to friction between elements. In cars without a rpm limiter the torque goes quickly down after the optimal rpm regime and the entire engine will eventually blow up.

So you can either model the rpm limiter with a simple:

if (rpms>limiter)
return -50;

Where -50 is an indicative negative torque you can use. Or you can model the descending torque curve after the optimal rpm regime.

In your example I don't see TDrive going to 0, it stays in the 1980 range. Also your slip ratio is VERY high, reaching 4, this means tyres are spinning 4x the speed of the road. If you have a linear relationship between SR and force you should increase the stiffness of the formula until you see values of about SR 0.2 once the car has passed 20-30 kmh (this depends also on the time step you are using).
With a slip ratio of 4, even if the engine produces 0 torque you still have to wait for the tyres to slow down and stop producing accelerating forces. This will also depend on the angular inertia you have set for the wheels and drivetrain system.