I recently (about 2 weeks ago) had my car completely straight-piped, no resonators, no mufflers, no cat. It sounds amazing now and I had no issues up until about an hour ago.

All of a sudden, while driving at around 45-50 mph, I noticed a pulsating sensation and popping noises coming from the exhaust. The popping noise happens in all gears, but mostly in Drive.

As for the pulsating, I only notice it while the car is actually moving, more so while accelerating. The noise happens simultaneously with each pulsation, and when I'm driving, it happens every 2-3 seconds, whenever I would stop at a light I noticed it occurred less often, usually every 5-10 seconds.

It used to sound smooth, now it's really choppy and uneven. Is this common or normal? And is it something that I should be worried about? How can I fix it? Is it an exhaust issue or and engine issue? Has anyone else ever experienced this before?

 

Two comments:

• Your engine computer has readjusted to the lower back pressure and has changed the air to fuel ratio, hence the "backfiring".
• Your modified exhaust system is causing many orders of magnitude more pollution to be dumped into the air we all have to breathe; please put your cats (at least) back in place.

 

Thank you for your reply.
I see how that makes sense, the ECU being readjusted. But does it seem logical that the problem took as long as it did to arise? I have no idea, that may be normal.

And about the cat, the shop didn't let me keep it, which pissed me off because he told me that he had to take them as I was pulling away. He said I would get a huge fine, although I'm sure he knew if anybody did, it would be him (there are no emissions tests or laws in Florida as far as I know). Trust me, I plan on getting a high-flow cat of some sort at some point in the near future.

*UPDATE
I had the ECU codes read at AutoZone and it read that cylinders 2,3,4,5, & 6 are misfiring. It seems to be running even worse now ( I have not driven it at all except to AutoZone and back as to not cause further damage). I had a feeling that it was a misfire, but not to that extent. I am bringing it to a trusted mechanic tomorrow to have him diagnose it. I know it could be a number of things, I've been Googling it. I will let you know what I find out.
Thanks again for replying.