Me and my buddy were pushing it a bit last night off a light in our cars and when he threw it into third his car just backfired and shot a nasty flame out the back. Does anyone know what exactly causes the car to do that or what modification causes it to happen?

 

You're probably on a test pipe and running a little rich.

 

Im running helix test pipe on my tbe at 21psi, 330whp now and it never backfires

 

vta bov?

 

Im running a hks ssq bov

 

Mine backfires as well. I have a Forge Evo15 with a Flash and I get back fires from 2-3rd and 3rd to 4th under WOT.

I am venting back into the intake and it still backfires so I dunno what the issue is really either. It's like it is VTA due to the rich spurt but I am not VTA.

 

i can add my name to the list, i think it happens when u redline though

 

Thats what i was thinking. My car rarely backfires but when i was getting it dynoed...we took it up to redline and it just let out a huge pop. That was the only time it backfired out of 5 or 6 dynos

 

If you use a recirculating BOV, the main cause of a backfire or flame out of the exhaust is running rich.

 

When you redline it might be cutting spark, but continue with a little fuel to follow with a reignition bouncing off redline or just the heat of the pistons, and boom.

 

I thought the main reason of using a recirculating is so you don't run rich.

 

the tune itself is most likely rich causing it....

 

It is. I wasnt pointing out the BOV as the problem, just the fact that the car is running rich period.

 

So many factors play into a car backfiring. About 4 of them are above.

....did someone say they have "straight pipes" on their evo? eww

 

How is that eww? I got rid of my highflow cat and got a helix test pipe so i dont have a cat no more.