Particle Script Help!!

[sagarasousuke 10]

Smoke rises to a plus side and both minus side of Z axis though I want to generate the particle of smoke like the following figures.

http://carview-img02.bmcdn.jp/minkara/mybbs/000/001/848/097/1848097/p1.jpg

>[]<

How should I do though want to jet like the vehicle exhaust only for one?

[]<

[]　・・・The object is shown.

＜ ・・・Direction of smoke (particle)

_ps1 = "#particlesource" createVehicleLocal getpos _obj;
_ps1 setparticlecircle [0,[0,0,0]];
_ps1 setParticleRandom [0, 
                       [0, 0, 0],
                       [1, 8, 1],
                        0, 
                        0.5,
                        [0, 0, 0, 0],
                         0,
                        0];

_ps1 setParticleParams [["\Ca\Data\ParticleEffects\Universal\Universal", 16, 7, 48], 
                       "",
                       "billboard",
                        1,
                        10,
                        [0, 0, 0],
                        [0, 0, 0],
                        0,
                        10,
                        7.9,
                        0.5,
                        [20, 20, 20],
                        [[1.0, 1.0, 1.0, 0.05], [1.0, 1.0, 1.0, 0.05], [1.0, 1.0, 1.0, 0.05]],
                        [0],
                        0,
                        0,
                        "",
                        "",
                        _pos];
_ps1 setDropInterval 0.1;