Backfiring?
Thread Starter
Racer
Joined: May 2010
Posts: 250
Likes: 1
From: MA
Backfiring?
Over the last couple months I've started to get a pop noise when shifting at speeds under 40 MPH. I'm not sure if its backfiring or a back pressure pop of some sort. I've got LG Pros into the LG cross pipe into Corsa Sports. The backfiring or pop noise happens when shifting between gears during normal acceleration. Is this some sort of exhaust leak? Didn't do it last summer.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
A misfire would usually cause a code---Normally a backfire with a miss would happen on acceleration-- It can be an exhaust leak--as when you shift the cold outside air would ignite any unburnt fuel in your pipes---- hard to say--without putting it on a data logger
Check for exhaust leaks---2nd all ignition parts--plugs and wires---and lastly an over rich condition would put lots of unburnt fuel in your pipes---You could have your fuel trims way off---if you recently re-oiled your CAI then that could be it--as your MAF gets fouled and makes it runs rich in return causes exhaust backfires or popping--- Clean your MAF
Check for exhaust leaks---2nd all ignition parts--plugs and wires---and lastly an over rich condition would put lots of unburnt fuel in your pipes---You could have your fuel trims way off---if you recently re-oiled your CAI then that could be it--as your MAF gets fouled and makes it runs rich in return causes exhaust backfires or popping--- Clean your MAF
Le Mans Master
Joined: Jul 2013
Posts: 5,699
Likes: 147
I had some popping on decel after putting in longtubes.
Turned out I had a silent exhaust leak on my Percy's dead soft
seal for good (!) aluminum gaskets.
I had an RXT clutch put in and the shop re and re the headers.
They said 2 tubes had black residue.
Now all is good.
Turned out I had a silent exhaust leak on my Percy's dead soft
seal for good (!) aluminum gaskets.
I had an RXT clutch put in and the shop re and re the headers.
They said 2 tubes had black residue.
Now all is good.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
There is a program in your ECM called "DFCO" decel fuel cutoff many tuners will turn this table OFF on some modded engines but mostly useful on cammed engines---A stock tune will shut the fuel off on rapid decel---then the cold air will ignite any fuel left in your exhaust causing it to go pop pop pop under deceleration----If you turn this OFF then the fuel is not turned off and the fuel residue in the pipes is so much it won't ignite--
They use DFCO to save fuel and increase mileage--On some larger cammed cars the engine may die if you don't turn DFCO off on rapid decel--
don't know if this is your issue---but your tuner can try to turn it off just to see if it helps---sometimes very efficient LT's will cause the same issue
They use DFCO to save fuel and increase mileage--On some larger cammed cars the engine may die if you don't turn DFCO off on rapid decel--
don't know if this is your issue---but your tuner can try to turn it off just to see if it helps---sometimes very efficient LT's will cause the same issue
Instructor
Joined: Jun 2015
Posts: 118
Likes: 8
A misfire would usually cause a code---Normally a backfire with a miss would happen on acceleration-- It can be an exhaust leak--as when you shift the cold outside air would ignite any unburnt fuel in your pipes---- hard to say--without putting it on a data logger
Check for exhaust leaks---2nd all ignition parts--plugs and wires---and lastly an over rich condition would put lots of unburnt fuel in your pipes---You could have your fuel trims way off---if you recently re-oiled your CAI then that could be it--as your MAF gets fouled and makes it runs rich in return causes exhaust backfires or popping--- Clean your MAF
Check for exhaust leaks---2nd all ignition parts--plugs and wires---and lastly an over rich condition would put lots of unburnt fuel in your pipes---You could have your fuel trims way off---if you recently re-oiled your CAI then that could be it--as your MAF gets fouled and makes it runs rich in return causes exhaust backfires or popping--- Clean your MAF
