Loud hum while driving on highway (and no its not the wind or the RPMs)

Hi guys 

Can I get some advice on whats happening with my Australian Jimny GL/lite? The car has 50 hours on the road since new in Aug, so Im reasonably familiar with it now. No modifications.

Today I went on the Suzuki Swarm with ~100 others from Melbourne to Apollo Bay, and the car did a few weird things.

1/. While winding thru the hills I was taking a sharp down hill left corner at ~45kmh and the front right (drivers) side of the car started shuddering and losing power (or maybe braking harder than I was pressing). There were no audible warning alarms but I didn’t get a chance to check the dash to see if the stability system kicked in. It felt like the wheel nuts were slightly loose or the car was spluttering on bad fuel… but only on the drivers side. I pulled over, had a look, couldn’t find anything and drove off. What was strange was that today I had taken many corners much harder than that. Maybe it was the stability system reacting to some combination of downhill slope, camber, speed etc. 

2/. I discovered the car has a ‘vehicle swaying’ alert, problem is the car definitely wasn’t swaying, I was driving on straight country road ~60-80KMH and it went off three different times. Asphalt was a bit patchy, but nothing too unusual.

3/. Sometimes previously when I have parked and walk past the front of the car I can hear a low volume high pitched electric whine. I've ignored it thinking its some mechanical shut down procedure for the fuel line.

4/. For many months now, when I accelerate moderately, about 1 second after I take off I hear a short groan/fart noise. Highly repeatable. I've read about chain slap, could it be that?

5/. Most worrying of all is that today while freeway driving at 100KMH/3000RPM in 5th gear for ~30min, the car developed a loud hum, louder than the usual wind noise thru the roof rack, and loud enough to irritate the hearing. Over the wind, road and engine noise, this hum sounds a bit like a muted car horn stuck on. To cut a long story short, the hum:

• Comes and goes periodically without any change in speed. 5-10 minutes every once and a while.
• Is not altered by gear changes.
• Is not diminished by depressing the clutch and coasting (1000RPM) in neutral at 100KMH
• Strangest of all, it continues when the vehicle is rapidly stopped and the engine switched OFF, but conveniently drops to silence over a period of ~10 seconds. Due to the sound of the passing freeway traffic I couldn’t tell where the sound was coming from after racing around to pop the bonnet a few times. So it doesnt appear to be related to the engine rotation or drive train rotation. The reduction in sound after stopping and killing ignition is quite linear, like something is depressurizing or discharging. 

Any thoughts?
 

I have seen a few reports about stability system / brake system activation under certain circumstances. All the articles read like yours, unfortunately very few report if the problem was solved or they just accept or avoid the situation. Issue 1 or 2 as reported could be this. Best get it checked by the dealer to make sure all the sensors are OK if possible. 

Suzuki dealer mechanic had the car over weekend and put 100kms on the clock but couldn't hear the problem, which is what I feared would happen. However I was able to find some videos I had recorded of the noises coming and going. All agreed its a loud and abnormal noise.

Up shot is Suzuki agree it is pressure related. Likely either the Positive Crankcase Ventilation valve or the 4x4 vacuum system. They replaced the PCV and checked the vacuum system and car didn't make the noise after this (not that they could get it to make the noise before either).

So more test driving for me to see if its resolved. Ill be putting a microphone under the bonnet if it starts up again and see if this allows me to pin point the source of the noise.

Thanks for the suggestions.