Date:         7 Nov 1995 16:13:37 -0800
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Harvey Chao" <Harvey_Chao@smtp.svl.trw.com>
Subject:      Re: What's a Backfire

                          Electronic Mail
                          Correspondence                      Date:   11/7/95
                                                              Time:   4:07 PM
Subject:  RE>What's a Backfire                    Ref:  

In general I understand a backfire to be any instance where the mixture in the
cylinder ignites and either the intake or exhaust valve hasn't yet closed. 
This then means that the ignition can vent through either the intake or
exhaust valve, hence the intake backfire (through the carb (dangerous fire
possibility?)  or FI a metering hardware ( expensive breakage possible of air
flow metering stuff) or via the exhaust system (rough on cat converters and or
mufflers).

My understanding is that the gross  causes are thus - 
o  Ignition timing off
o  Valve timing off
o  hot cylinder deposits igniting the mixture instead of the spark plug.

Maybe someone else out there has more specific suggestions on where to
start/look to fix your backfire problem.

Harvey