louczar

2015 RWD RC350 with the upgraded OEM exhaust installed at the factory. No other mods.

In slow moving traffic on the highway on my way home in the left lane next to the diving wall between the north and south bound lanes. If the traffic moves up to the upper teens in MPH and everyone starts to slow down, I will get a very minor sound that almost sounds like a minor backfire when the speed drops back down to 13-15MPH. I dont hear it if I am not next to the wall. It doesn't happen (or I never heard it ) when the outside temperature is in the 60's or lower. I have to have my window open to hear it too. I dont feel it either. Only the sound.

Anyone else experienced or heard of this before?

Crown7

I have an invidia q300 and it does make a popping sound as well, although it does it quite often. When the car is coming to a stop using engine braking and the throttle bodies are closed, there is a vacuum in the system. The exhaust is the tail end of the vacuum and when the engine disengages and resumes normal idle, the pressure will equalize and make a popping sound much like opening a bottle of champagne!

lexual_rc

There's generally some confusion around the definition 'backfire' in cars. Generally, backfires are not a good sign of efficient engine performance and due to a number of things, namely: running too rich, distributor caps being cracked, carbon tracking on spark plug wires and or engine timings being incorrect. Backfiring is the process of a spark plug, or multiple spark plugs, igniting the fuel in their cylinder out of turn, in a part of the combustion process where the exhaust valve is open on that cylinder and caused usually by those previously mentioned causes.

That being said, its not always the case that what you are experiencing is a true back fire for those reasons. For example, I have removed my muffler and use custom straight pipes from the factory resonators back and occasionally experience the pop or build up/pop you may also be hearing. This also generally happens when I downshift from a higher RPM range but it happens very rarely. Being as my car is fairly new and the 'issue' (I actually enjoy it from time to time) is very minimal in nature, I've ruled out any serious issues like those I previously mentioned. Since you are using a factory exhaust, I would not expect you to experience the same issue and an inspection from your local dealership or other certified mechanic may be give you better diagnosis and put your mind at ease. Hope this helps and good luck!

Jaywreck

louczar

Thanks for the confirmation. Your scenario is almost the exact same as mine. The only difference is that it happens with just normal driving too.

LEXUSGREG1

the more i upgrade my power, the more it pops. pops when lean, pops when rich, pops when just right. all kinds of pops all the time lol esp when its cold out and the engine is just warmed up a lil