Help, Someone Put A Flamethrower In My Ass

[wraith_skyline]

Hey guys, i am getting some pretty mad flames and bang noises coming out my exhaust on gear changes and engine braking, i have been told its overfueling or the cat is dead. I have checked both of these, A/F is fine and the cat is only 15k old. If anyone has any suggestions on this they would help.

Current specs are

ARC monster intercooler

10-15psi boost, depending on what i am doing

2.5inch Apexi Y piece

3.5inch straight through drag exhaust

Stock turbos and computer

[The Mafia]

if you have an aftermarket BOV, its that.

If you have a Factory ECU, its that.

If you have both, then its both.

[QWK32]

if you have an aftermarket BOV, its that.

If you have a Factory ECU, its that.

If you have both, then its both.

i run an aftermarket bov venting to atmo with out backfiring, and untill a couple of months ago i still ran the standard ecu. all without having a noticable backfire or flames.

wraith_skyline, whats the rest of your exhaust setup like? straight through? Cannon? and whats you spark plug condition? i know that the std computer tends to rich out under load, and if your plugs are in need of attention and and not giving a good spark you may end up with unburnt fuel. and how do you know your a/f is fine?

if your cat is stuffed and with a straight through exhaust, or one with just a cannon on the end, there would be nothing to muffle the backfire and contain the flames if you get a backfire.

[R31Nismoid]

As Mafia said, if you have non-factory BOV's, thats the problem.

If not, then possible your plugs need attention, or timing needs to be looked at.

Im running 250rwkw on the stock ECU at the moment and in my travels never had a problem

Have you recently changed anything?

Ie it was ok at one point and its 'just started', or, have you changed something recently and not long after 'started' to occur? Need to esablish that

If its not plugs/BOV/Fuel reg failing... then i'd put it down to running a larger cooler without ECU.

Interested to know also how you know the AFR's are ok, cause generally the situation you say its popping wont be simulated on a dyno.

[wraith_skyline]

Yeah i think you all might be right, it is running aftermarket BOVs, but it did it before they were changed, the exhaust is a straight through, no bends or mufflers till the cannon. As for the AFRs they were ok on the dyno, but like you say they will be different on the street. I checked the plugs a little while ago, but i was gunna replace them soon anyways