What causes backfire?

[Habbibie]

Honestly I don't know what exactly causes it but my expedition is having it, you know the gurgling of the exhaust after it shifts or if you rev it in neutral/park.

I'm not gonna lie I like it lol and its probably running rich that's why its gurgling but I cant imagine it hurting the 7.3 mpg I'm already getting with it!!!!

Anyways if you can steer me in the way of a possible fix I'll fix it since i LITERALLY have nothing to do in the new house i bought, its too damn new that nothing is broken yet so I'm pretty much idle and bored in the evenings....

 

[1955moose]

Well Habbibie from what I remember, backfiring is caused by a fuel charge that doesn't get exploded by the spark at the right time. Every see an old model T or A, yeah I know what you perverts are thinking! If the manual spark advance was not advanced properly, a backfire would occur. But when a fuel charge has a spark that's too late, say at top dead center or later, it fires on the down stroke of the piston/crankshaft, instead of before top dead center, usually anywhere from 2 to 12 degrees before. Your rich fuel charge needs to be fixed. Have you checked your fuel trims? I'm betting either you gotta bum fuel pressure regulator, or a wonky 02 sensor, that's letting it run rich.

Sent from my N9131 using Tapatalk

 

[ChrisOIFdoc]

Well Habbibie from what I remember, backfiring is caused by a fuel charge that doesn't get exploded by the spark at the right time. Every see an old model T or A, yeah I know what you perverts are thinking! If the manual spark advance was not advanced properly, a backfire would occur. But when a fuel charge has a spark that's too late, say at top dead center or later, it fires on the down stroke of the piston/crankshaft, instead of before top dead center, usually anywhere from 2 to 12 degrees before. Your rich fuel charge needs to be fixed. Have you checked your fuel trims? I'm betting either you gotta bum fuel pressure regulator, or a wonky 02 sensor, that's letting it run rich.

Sent from my N9131 using Tapatalk

I was gonna say too many frijoles but your explanation will work too

 

[Flexpedition]

Deceleration gurgle (as described in post 1) and backfire (in title) are two completely different items.

When you rev the engine and let off the accelerator & there is little to no engine load, ie: when parked or in neutral, deceleration gurgle is actually normal.