Questions before taking car to dealer

[AUTiger13]

Preface: I have done multiple searches and could never find a thread close to what my potential problem could be. Im looking for some guidance/clarification before I take my car to the dealership this weekend so I don't receive the old "its suppose to do that" from the service tech.

Problem: Recently, I have noticed what seems to sound like a knocking or pinging noise when the car automatically blips the throttle on aggressive downshifts. I can replicate the noise by placing my car in M-mode and downshifting from 3 to 2, and 2 to 1 aggressively. The noise doesn't last for more than a second or so, but it definitely sounds like detonation to me. I have tried multiple "top tier" gas vendors (Shell, Exxon) and I can still replicate the sound. Has anyone ever experienced anything like this before? The car only has 16,000 miles so I want to get this checked out before any damage occurs.

The reason for this post is because I've heard stories of techs being lazy and claiming its a "normal" sound the car makes due to its performance nature, etc, etc, etc., especially if you are younger (Im 23). I am doing my due diligence regarding the normal noises in case the tech does try to pull that card out on me, and hopefully by providing BMW NA literature stating what is normal/(not normal), I can get my car diagnosed correctly and without any trouble. In my research, I have found the following publication from BMW NA regarding normal noises that occur with this car:

"1.0 Engine
The new S65B40 V8 engine is a high performance engine designed and built to exacting BMW Motorsport tolerances which take into account the high performance nature of this engine.
The new S65B40 V8 engine has the following characteristic sounds which dealers need to be aware of.

1.1 Knocking type sound at idle
When the engine is at normal operating temperature and depending upon the accessory loads on the engine it is possible a low frequency knocking type noise may be heard in the car. This noise is a characteristic of the engine and is not an indication that there is a defect with the engine. In the event that you receive an inquiry about this noise it is important to reassure the customer that this
noise is a characteristic of this engine. The noise in no way affects the durability of the engine and will not lead to a failure of engine components.

1.2 Resonance at 2,000 rpm under load
The M3 has a characteristic resonance which occurs in a narrow rpm and load band. The resonance is directly related to the performance characteristics of the M3 engine and in keeping with the performance nature of the vehicle.
The driving conditions under which this resonance will be heard:
• Engine speed = 2,000 rpm
• Vehicle speed = approx 70-80 km
• Gear selected = 5th gear
• Road conditions = moderate incline"

Has anyone found any other guidances/publications by BMW that reference any sort of "knocking," "pinging," or "detonation?" If so, I would greatly appreciate the text so I can see if this is normal or potentially a serious problem.

Sorry for the long post, but thank you all in advance.
Jeff

[AUTiger13]

For clarification purposes, the car is a 2011 e93 with DCT

[AUTiger13]

For anyone in Houston looking for a good service department, I recommend Nick (SA) at Advantage Midtown. I made an appointment finally to get my issue checked out. Showed up, spoke to Nick and I drove around the Shop Foreman out for a drive. He heard the noise (thank god) and is perplexed on what it could be. He mentioned it wasn't a knocking sound, as he said it would throw a code if it was knocking, but the noise was more "tinny" as in metallic sounding.

I made an appointment to leave my car there with them for a day and they are setting me up with a loaner.

Now for my question about the VANOS. Ive read a few threads about a metallic noise at start-up that was being caused by faulty VANOS check values. I was wondering if anyone has heard of anyone having problems with their VANOS systems during higher rpms. Most of the issues with the check values seemed to be right around 1,500 rpm.

[dparm]

I've noticed the throttle-blip on downshifts sometimes takes on an unusual sound. I think it's just the nature of the motor and the fact that the engine produces some interesting harmonics from the ITBs and big plenum, and the overall aggressive nature of the motor. Sometimes the noise is a crackle or harsh pop, and other times it's just a normal rev sound.

If you have access to a USB-OBD2 reader, you should be able to watch the misfire counter to see if anything unusual is happening. I'd also start taking notes on when you notice this (i.e. ambient temp, oil temp, speed, RPM, gear, Drivelogic mode, etc). Perhaps a pattern will emerge.

In my opinion it sounds like normal operation.

[AUTiger13]

Update, and with worse symptoms.

I drove the shop foreman, Bill at Advantage Midtown in Houston, for a drive and he heard the sounds. I let them have the car for a day and a half and they "found normal operation with no abnormal noises." I knew that this was going to be the end result, but things have gotten worse since I picked the car up.

They did state they reset the transmission (DCT) relearn, and a few other things to the transmission to diagnose things. From my conversation with my service advisor, it seems they focused solely on the transmission, when the problems are coming from the engine.

Since I picked up my car, I have used just about every gas station in my area, all BMW recommended. The noise, which has become louder and more frequent, has occurred on every 93 octane gas, thereby essentially ruling out bad gas. The "knocking" sound has so loud now that I can describe it a different way to see if anyone could shed some light.

The sound is definitely metallic, almost like the sound of gears grinding and someone is hitting a hammer on a dense piece of metal, with mid force. I have tried to capture the noise, as it happens during normal acceleration now, with my phone, but you can not hear the noise as clearly as in person. I can be in any gear, any amount of engine load, and at any rpm, and the noise will be present. I am also experiencing loss of power, loud "pops" in the exhaust when downshifting (sounds like its coming from near my feet), and very jerky. The rpms will fluctuate at start-up, however, it goes from 500-1000 and sounds like its going to kill the engine.

As dparm posted above to record when I hear the noise as to develop a trend, I have. The noise is present no matter if the engine is at temp or soon after a cold start. It has been quite cold here and never take the engine up past 3000 until the oil level displays. The noise happens especially during the tip-in of throttle, during normal, medium, hard accelerations, when upshifting, and downshifting. I have tried to trust that this is normal operation, but I know this is about to turn into something bad. I drove the car after I got it from the dealer for about 100 to 150 miles to rule out my OCD-self from the picture; I definitely am not hearing things.

I just want this thing fixed so I can go drive it! I am calling the dealer tomorrow to take it back in, and I am going to drive the foreman and my service advisor around until they see that something is wrong.

[1fastdoc]

I think you're going to drive yourself insane. It's under warranty. Drive the shit out of it and if the problem gets worse, it will become apparent to the SA. If not but you're still concerned, sell it before the warranty expires.

[Koldun]

The Advantage people are good folks. They aren't super fond of mods, but the service department does clean work. Just stay away from Momentum and good luck with your car!