Explotions, Need Info

[CR320i]

[B] I was driving to work a few minutes ago, when coming down the freeway
the car made a sound like an explotion, a fellow of mine who was behind told me he saw like a little flash-fire.
The car did the same sound 3 times.
This was a short trip no more than 13 km


I was driving at 100 km/p/h i was in 3rd gear down hill when the explotion became.

---on saturday i went to the mechanic and he ¨did a tune up, valve adjustment and he adjusted the distributor which was with a weird sound from a few days ago.
gimme a clue please on what is the origin of the sound-explotion.

JT
Car is an E30, 320i european version, 09/84 production date model 1985.

[pimprider]

could be your engine timing? explosion and flash fire frm your tail pipe could mean misfiring of your spark plugs?

[mosyslack]

kinda sounds like a after-fire, like a backfire but throught the exhaust. I believe that is from timing, and engine set-up (if there are any add-ons and such). Could be a issue with excessive pressures and the such. If it's fixed, great

dave