Deliberate backfires?

An increasing number of local teenagers driving sport models of Mustangs or various compact cars like Corollas have their mostly late model or even new cars consistently backfiring very loudly under rapid acceleration and deceleration, especially going up and down hills.

These aren’t old beater cars; these are newer cars. Most also are equipped with obnoxiously loud speakers that the bass can be heard and felt from blocks away.

They seem mostly to be automatics, if that makes a difference.

I assume the recent explosion (pun intended) of the these very loudly backfiring cars is some sort of trendy status.

In addition, under hard acceleration and deceleration the engines sound very loud and very rough. It’s as if the kids are trying to have their cars sound like track dragsters. For that matter, most Friday and Saturday nights I can hear them drag racing on a stretch of road about a mile away.

I’m curious, how do they “achieve” the consistent backfires? And how without damaging the engines? :thinking:

P.S. Does anyone have Marvin the Martian’s ray gun I can borrow to zap those engines when they go racing past my house at 3 a.m.? :rofl:

For the record, I’m not really complaining, just mostly curious. Yes, it is mildly annoying at times but hardly anything to get worked up about. And despite my having been fairly tame at that age I recall my friends and I causing our parents and neighbors some exasperation. :grin:

But back in the carbureted days before steering wheel locks, you’d turn off the ignition with the car in gear letting the coast-down draw in excess fuel. Then you turn the ignition to “run,” the engine restarts and backfires the excess fuel.

These might be turbo-charged cars with an exhaust wastegate not dumping into the downstream exhaust pipe but into the open. Rev the car up, snap the throttle shut, the waste-gate opens and pops exhaust out the “screamer pipe.” You can probably install a wastegate on a non-turbo car to crack open the exhaust on throttle drop just to be annoying.

And being publicly annoying is a teenage rite of passage as I recall. :roll_eyes::grin:


Speaking as someone who taught and counseled teenagers for 35 years, I can say that your recollections are correct.


Something like this ?

Somewhat like that but less a racing engine sound and more rough. And the backfires are harder, louder, and consistently at least six to seven in a row, sometimes as many as a dozen, spaced surprisingly consistently timed apart more than random backfires.

If it makes you feel any better, those young fools are going to have spend a lot of money on their exhaust systems in the near future.

I’ve been wondering, as from years reading here in the forum I gathered that chronic backfires are destructive to exhaust systems and engines.

It’s what got me to posting this topic because I’m curious if these kids have found a way to set the cars doing this without harming their machines.

As Mustangman noted earlier, this worked quite well back in the carburetor days. I did it quite often back then. The resulting backfire was very loud, especially when done inside a tunnel.

I eventually stopped after blowing a muffler wide open.

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The popping on the overrun (when you let off the throttle at higher revs or downshift and let the car decelerate) can be achieved with some ECU tuning if desired or can be a side effect of ECU tuning. My car will do it sometimes, but generally not all that loud or dramatic, if you were in the car or nearby you could hear it, but if not if you were like 100 yards away or anything. Basically what happens is extra fuel in introduced and doesn’t always get burned in the combustion process, and makes to the hot exhaust system and then combusts making small explosion. that small explosion in the exhaust system is what makes the noise. To make it happen when you’re on the gas you need a 2 step rev limiter. Basically you set an RPM , typically this the RPM that you want to launch the car from when drag racing. You stand on the gas the RPM’s go up and bounce off the rev limiter, this will make for all kinds of loud noises as the ECU tries to cut fuel and/or spark in rapid succession. Some turbo cars will use a similar system for an anti-lag feature.

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@FoDaddy Thank you for the explanation. :+1::slightly_smiling_face:

I’ve noticed that trend around here too. Some nights sounds like someone’s firing a machine gun out on the highway.

I vaguely remember “SavageGeese” on youtube reviewing a couple of exotic cars that backfire a little on decel when switched to “sport” or “track” mode.
Anyway, youngsters like to make noise. Sorta like peacocks and their feathers.

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My motorcycle can produce unbelievable backfires that are great for scaring off dogs that chase. Flip run switch to off without reducing throttle position and flip back on after a second or two. Longer wait equals greater effect but beyond a few secs is concerning for damage. Want to see a dog at full run barking do a 180 and run even faster the other way? Good times…

Why do you believe they care about damage, or even think about it?

One can cause deliberate backfires on the old Harleys. Open the right side twist grip for the throttle, snap it closed, and while doing that rotate the left twist grip forward which retards the cable operated ignition timer (or distributor of sorts) for easier starting.

A 4 or 5 foot long blue/white flame will shoot out of the exhaust along with a loud shotgun boom. It’s a real hoot to do this at night.

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Only if they choose to fix those exhaust systems will it cost em.

Their parents, you mean.


I notice some motorcyclists accelerate uniformly to speed, minimizing noise, while others alternate between accelerating and decelerating, maximizing sound. And I’m sure some people remove their mufflers, the noise their compacts make.

In my experience the car teenagers eventually grow out of being obnoxious idiots. The Harley guys often keep being as loud as possible well into retirement.


I guess I haven’t gotten away from my teenage years. I bought a battery powered lawn mower from a friend several years ago. It was too quiet, so I mounted a model airplane engine on the handle so people would know I was mowing. The battery mower has since died, so I am back to a good old noisy gasoline mower.