A couple months ago, my JCW pro exhaust stopped the loud pops and bangs. I still hear the flap opening and get the louder exhaust sound, but when down shifting manually and letting it sit higher in the RPMs and letting off the gas it used to be good and loud. That is no more. I asked the dealer, they changed the battery in the remote but there’s no improvement. They say it works as it should but that’s clearly not the case.

There is a faint braaap on upshifts but not as loud as before.

Anyone had this issue or any idea what it could be?? Is the flap not opening all the way? The exhaust is 2 years old (I also have the ecu tune), been through 2 winters. Is there some maintenance required? Is there a chance they overwrote the tune of there was a software update? I don’t open it all that often but when I do I prefer the raucous loud pops. Any help would be appreciated

 

Open the flap, and walk to the back of the car. Youl hear the difference.

 

Its the pops and bangs when I’m decelerating/downshifting that are gone. If I’m behind the car to listing I have a much bigger problem to worry about!

 

If the flap is opening, its not the exhaust. Was there a software update recently uploaded to the car? If there was an update, its possible it changed some of the mapping to reduce the overrun noises.

 

None that I am aware of. It stopped popping between service visits, so I figured it was potentially the battery that was dying and maybe the signal it sent on low charge was insufficient to open the flap completely. I just changed the battery, it opens with less frantic pressing of the remote button…and there is a more audible braaap on upshifts that also went away…but the pops would wake up the alter cockers, they are gone completely.

I feel neutered like an LCI only with less horsepower to offset the disappointment.

 

You asked if the flap was partially opening, as I said start the car open the flap and go to the back a

 

I just had my battery changed and got the latest update so I'm curious if this has affected mine now that you say something. I feel like the exhaust is actually a little louder after the update, but I haven't ran the car in sport mode to see if it still pops and bangs. Guys I'm waking people up in the morning!!

On a side note I asked the service manager if the update would affect the tune and she couldn't really tell me. I asked if the Pro Tune was a "hard" flash vs a "soft" flash. Again I kind got deer is the head lights. With a soft flash you will lose it if power is lost and a hard flash is more of an update and it actually rewrites the ECM and it's there permenantly.

Side note #2 and this will help the OP. Is there a way to tell in the car if the tune is intact and not reverted back to the standard S map/ tune? Would the flap still work with the tune lost?

 

The exhaust has nothing to do with the actual pops and bangs. When opened, the exhaust will be louder and so would the pops and bangs. My car only pops and bangs in sports mode.

 

Sorry misunderstood I thought you meant to listen for the sound. I’ll check, the dealer said it is working as it should but they didn’t go for a test drive. They would bill be an hour…frankly I should bill them to rip around in my car!

 

the flap is just a mechanical part in the exhaust that is controlled with the Bluetooth signal. The flash wouldn’t have anything to do with it opening, but I get the sense that living with 4 seasons may mean some maintenance (like greasing the parts) or whatever may be needed for the baffle to open as intended? No clue just an educated guess.

I’ll check tomorrow if the service advisor can tell me if a flash from service could overwrite the tune. That sounds crazy, you’d think it would have to be a hard flash.

 

I’d be surprised if the JCW tuning kit ECU remap was somehow overridden by a dealer update or something. The ECU remap that the now older F5X cars had available is essentially an option code as far as I know. When the dealer does the remap, they essentially permanently add the option code(s) for the JCW tuning kit to your car’s VO.

 

The Pops and Bangs are not from the flap. They are from the injectors still running a bit of fuel into the combustion chamber when the exhaust valves are open. It's a "waste" of fuel which many people prefer, and that has been proven to not be harmful.

Why your injectors wouldn't still dump that little extra fuel on deceleration, I don't know.

By the way, those with 2020 and newer JCW's with the 300+ HP systems are complaining that their Pops and Bangs have been neutered. Well, they cleaned up the injector "over-run", so, they lost that extra sound (for the most part...I understand a couple of people have newer cars that will at least burble on deceleration).

 

Your replies are always so well articulated. So, the issue is seeming with the programming that no longer tells the injectors to dump the little extra bit of fuel, or potentially the injectors themselves (like they need a cleaning)? My car is a 2017 with under 40k KM. Nothing should be needing replacement in the engine at this point. My MPG is pretty crummy, but I figure that’s mostly city driving in sport.

 

I'm glad you brought that up! That was something that crossed my mind, but, I'm not an expert in these cars, so, I thought it would be better not to guess at something that I'm not sure about. That said, it's what I would think if it were my car...I'd run a bottle of techron through a tank of gas and HOPE it would be the solution.

Again, I don't claim to know!

(and, thanks for compliment!)

 

Sounds very logical. I can try techron. In the rabbit hole of articles it says I should do it before getting an oil change since the oil can be contaminated? I have to see the dealer tomorrow and will see what they have to say. For them not to suggest it as a potential fix seems silly…thanks for the feedback!

 

The most careful people do it that way, yes. Especially with some Direct Injection engines, there is a tendency for "oil dilution" from unburned fuel. I don't see reports of these BMW engines having this tendency as badly as say, the Honda 1.5 Turbo, but, it's not a bad idea to wait until just before an oil change....just in case! Good luck with finding the reason(s)!

 

Thanks @Mini-Titan . My oil change is only due in spring, but I’d like to thing your very logical approach is something they would have considered. Even if they were trying to sell me the service of cleaning the injectors I’d like to think they would have considered it. Even if it’s not the solution it makes more sense then charging me to road test the car and not hear the pops. Shrugging it off seems to suggest they aren’t aware of how the system works.

 

I would be curious how I would ask the dealer to perform this remap on my 23' JCW.

 

It was only available for 2020 and older Cooper S models. If you want a tune for your JCW, you’ll have to go aftermarket. (I strongly recommend Mario Palza aka @MarioKart .)

 

It's probably your fuel. You may want to try this first: When low, fill up with tier 1 gas, highest octane available (Shell, Phillips, etc.-do a search). My '15 S (with JCW tune, exhaust, always run in sport mode) will always go "silent" with cheap gas from Sam's and convenient stores. Half a tank of the "good stuff" and the sounds come back.

 

You're in Sport mode, right? Also try turning on dynamic traction control (one press on the TC switch), that makes mine pop nicely.