[Gizm0]

Hey guys, I installed a JB4 NLS/2step kit on my car last week, upgraded the JB4 firmware to the latest 32_2.

Since then, my car has been popping the loudest backfires between every gear change when I get on it. It sounds like a gunshot!

Last night I raced a friend in his procharged 2 valve mustang and he said my car was shooting 2ft long blue flames out the tail pipes. When I raced him, I was lifting between gears and the NLS was set at 5500rpm. I was shifting around 6200rpm. It popped every time I up shifted, no matter what gear.

Now don't get me wrong, I love the backfire sound and flames shooting out the exhaust, I think it's pretty sick, but I'm pretty sure it shouldn't be happening, especially since I still have a stock catback!

What's causing this? I did a log and the car isn't running rich... I have watched many videos of N54 on youtube and never heard any doing this... except for this guy here, mine sounds exactly the same...

[Antetokounmpo]

afterfire. extremely common on catless turbo cars. the nls cuts ignition so it's very common for the unburned fuel to ignite when it encounters oxygen.

[Gizm0]

Here is a video from last night, after I installed a catback exhaust.

[BKBMW335I]

Not trying to thread jack or anything like that but today I had major backfire so loud and I was able to see flames, it actually scared me and made me raise up off the accelerator.

If you are using Meth or Ethanol then you are probably more likely to see flames especially in the N55s since the exhaust gurgles and pops are unburt fuel.

My car has never done this before but I added a little more ethanol than I normally do when I fill up so I'm certain that had everything to do with why it backfired and popped so loudly.

Another unusual thing is that it was like I could feel a little lag and build up of boost pressure and then my rear wheels caught and it felt as though my engine was about to blow.