When I coast down the road and around the corner to our house I'm usually in 2nd on over-run, then park in the drive or go down it to the garage under the house and turn off, after a second or two there is often a distinct quiet 'doof' from the exaust...

 

Not every time, and quiet enough that you have to listen for it, but it is quite distinct.

 

I assumne its unburnt fuel vapour in the exhaust somewhere... Any ideas?? Anyone else had this??

 

The only thing I can put it down to is unburnt vapour in the last cylinder under compression leaking out through a burnt valve/seat and igniting in the exhaust pipe. As its a second or two after turning off I didn't think there would be anythig to ignite it in there...

A bit of residual heat in the exhaust is all it takes to ignite some un-burnt fuel. That's how my mazda blows awesome flames.

 

Have you tried not costing it home for the last bit of your trip. Maybe also try giving it a rev just before you switch it off and see if it still does it.

Edited September 17, 201016 yr by Taz_Rx

Keybangers! WOOOOO! :P

check your ignition timing.

 

are the points very old?