i am an 8 onwer my self for about 4 months. every time when my car is park , n i rev it up to abut 4-5k rpm. after the rpm starts droping i heard back fire. any one know why is that happaning?

 

It is normal and caused by unburnt fuel igniting in the exhaust system.

 

I have the same backfire issue that you are talking about. I dont worry about it too much. It seems to get better or worse depending of the octane of fuel that I used

 

Really?

 

I haven't heard of this before

 

Yeah, if I use 87 octane fuel it doesnt backfire as much/as easily as when I use 93 octane fuel. I usually use higher octane fuel (depending on how much money I have for gas lol). It never backfires during normal driving and i dont rev the engine very much when im sitting still so i hardly ever notice it.

 

This is normal for a rotary, My first rotary was a 71' RX-2 and they installed a valve upside down(from the factory) and you could get it to Back-Fire like a cherry bomb on demand. Its good they had a strong exhaust.

 

Nope. I can't put my car in "Park."

But seriously, my car has never backfired.

 

This would make sense, the 87 burns more completely in a rotary then higher octane. That is why 87 is often reported as having more power or better mileage in some rotaries.