I have a suspicion that my car shoots flames out the exhaust?

Question

I'm being completely serious. I have a Scion tC which I run a modified exhaust on. It's all aftermarket from the header all the way back, no catalytic converters, just a resonator and muffler. My car does throw the P0420 code, so I believe my car runs rich as well.

I've noticed lately that when I've been driving my car for awhile and everything is warmed up, my exhaust pops and crackles a lot when I'm decelerating in gear. I don't mind that, it actually sounds really good and it's not very loud. But what I've become more concerned about is sometimes I get one really loud POP once in awhile. I wouldn't mind that either, but over the past few weeks I've noticed that when I'm driving around town and there's someone behind me when my car makes that loud pop, that they will back way off. Like they'll be almost tailgating me once second, and after my car makes that loud pop, they now back off a few car lengths.

Could my car be shooting a flame or flames out the exhaust when this happens? I kind of doubt it, but why would people back off? I mean if it does backfire, it wouldn't shoot a huge fireball obviously right? I didn't intentionally try to modify my car to do this either, it's not like it's even powerful or anything in the first place. What do you think?

thebax2006 · Answer

The P0420 code is the code you get for needing a converter. The fact that this code sets is proof the 02 sensors are working. With the headers and straight pipes you've eliminated the back pressure that your valves need which causes a loss of low end torque and the backfiring through the exhaust system.

? · Answer

Mitsubishi master tech is 100% correct.....All that high dollar exhaust **** you got, is exactly that....its **** !!
Exhaust flow and back-pressure is a necessary part of the combustion process...Even if your fuel system is working properly, unburned gases build up in the pipes, and eventually must explode.  The function of the Cat Converter is to fire-off at 2500 RPM and burn all those gases away...For some reason all you guys think that by getting rid of those exhaust components your gaining performance...Guess what....Yea, in 1975 that was kinda true....Now....NO...The combustion process has become so efficient any changes actually reduce your performance....But the guys who want to sell you a $1500 dollar exhaust system, sure as **** aint gonna tell you that.....C'mon you guys....Wise the **** up already

? · Answer

Lamborghinis shoot flames when they downshift. And no it's just a short burst of flames coming like 5 inches out the pipe not a fireball

Skoda John · Answer

Get someone to follow you 
The pop is probably a backfire. You have air leaks in the system and each pop is causing damage.

Aftermarket parts will give all sorts of issues and usually reduce performance for the car. 
Keep it stock.

Anonymous · Answer

"My car does throw the P0420 code, so I believe my car runs rich as well"

Where did you get this nutty idea? The 420 code has nothing to do with the mixture.
Go look in your garbage bin at the $1200 worth of catalytic converter you pulled off and guess again.

? · Answer

Have somebody drive it by at night (or have them take a video while you drive) and watch.

You will probably just see little pops - rather than flames.

People are backing off because they think your muffler is going to explode and shower their car with bits of hot metal.

? · Answer

You said it's backfiring.  So isn't there enough NOISE coming out, to startle somebody???

So you don't have a cat. converter!  Do you have any O2 sensors??

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I have a suspicion that my car shoots flames out the exhaust?

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