Waze dont follow my car when I drive... iphone 3 g

Hello, I have a waze in my iphone 3g.
My problem is this, Waze don’t follow my car wend i drive, so every time that i want to know were I am, i have to check for position manually.

It find my position very well, but docent do automatic.
So any idea ???
Iphone 3g software 4.2.1

Thanks in advance…
Richard

The 3G phone does not have very good GPS reception. My car would also be all over the place on my 3G. I upgraded to an iphone 4 and most of those problems went away.