Tach spike
 

Sometimes at idle, my tach will spike to around 4k really quick and then go back down. It always catches my attemtion and when I look at it, it is just sitting where it is supposed to. What could cause this to spike like that? BTW - I have a msd 6al that my tach is hooked to, and the tach is an Auto Meter 5" monster with mem. recall and shift light. Thanks for the help.

Caymon