Anyone notice any Engine Knock?

[J08M3]

I've noticed a noise under hard acceleration, 75%-100% throttle starting around 3,000 RPM. It almost sounds like a slight vibration/rattle sound coming from the engine. Has anyone else noticed anything like this? I'm wondering if it's possible this is engine knock? First thing I tried was a full tank of gas from another gas station to see if there was any difference. I only use 93 octane gas. I noticed no difference between Hess gas where I normally go, and Mobil where I go sometimes. I don't have many other options near me.

Or is it possible this sound is completely normal? Anyone else notice something similar to a rattle under hard acceleration?

[newtom3]

I have not pushed it very hard yet, but no knocks or pinging at all so far.

[revmmm]

No knocking here. I always use Sunoco 94. Interesting to hear if anyone else has the knocking. The only noises I hear are a low "clunk" when I shift to reverse (6MT) and also the car excelerates a little choppy from 1st when it is cold, but otherwise no other issues.

[Ali.K_BMW]

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

The resonance band is very narrow and can easily be avoided by reducing the load on the engine or bychanging down or up a gear depending upon the driving conditions.

[J08M3]

I'm not positive it's knocking. I wish I had video or sound clip. But it does have me wondering if it is. It definitely has a different sound under hard acceleration. That sound certainly sounds like a rattle or vibration. Not a knocking sound like a bent rod or something along those lines, but like pre-detonation sound. I might have to take a BMW mechanic for a ride with me to confirm this sound. I wanted to get a third party opinion first though.

[J08M3]

Originally Posted by Ali@TurnersvilleBMW

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
The resonance band is very narrow and can easily be avoided by reducing the load on the engine or by
changing down or up a gear depending upon the driving conditions.

That knocking sound described here is the opposite of what I stated. This states at idle. I'm talking about under 3/4 - full throttle over 3,000 RPM. This is nothing like the idle sound that is expected from this engine.

[lilcow]

Ali. Is this also related to the ticking/clicking sound mentioned in some of the other threads? Ticking/clicking do not seem related to what you mentioned about the S65B40 engine.

Originally Posted by Ali@TurnersvilleBMW

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

The resonance band is very narrow and can easily be avoided by reducing the load on the engine or bychanging down or up a gear depending upon the driving conditions.

[Rovman]

Originally Posted by J08M3

I've noticed a noise under hard acceleration, 75%-100% throttle starting around 3,000 RPM. It almost sounds like a slight vibration/rattle sound coming from the engine. Has anyone else noticed anything like this? I'm wondering if it's possible this is engine knock? First thing I tried was a full tank of gas from another gas station to see if there was any difference. I only use 93 octane gas. I noticed no difference between Hess gas where I normally go, and Mobil where I go sometimes. I don't have many other options near me.

Or is it possible this sound is completely normal? Anyone else notice something similar to a rattle under hard acceleration?

I have been experiencing the same noises with my car as you have. In fact, I was having a problem with my car losing performance only when the car was making that noise. Making me think it was a knocking and pinging, hence the loss in performance, as the ECU would pull(retard) timing attempting to stop the detonation.

I have to comment that my technician really worked hard on trying to fix my car. He checked the fuel quality 1st, low and behold he found a 12-14% amount of alcohol(ethanol) mixed within the fuel. He told me that the car really was not designed to run on a higher than %10 mixture of alcohol in the fuel. For clarification sake I ALWAYS run 93 octanes top tier fuels in my car. This instance I had just filled up at a local SHELL station.

Solution: he flushed the fuel and replaced it with more 93 octane and advised me to drive the car and see if it any better. Unfortunately, I drove the car for 4 more tanks worth and the car had significant power reduction, along with surging are loss of power while the slightly audible noise persisted during the 2500 - 3800 rpm rev range.

Step 2- After continued driving of the car, 4 tanks later. The car was no better. I brought the car back for service. The decision was then made to replace the injectors, under the pretense that possibly the tainted fuel could have damaged them in some way.

Solution #2: I get the car back with the injectors replaced and the car is improved but only slightly. The noise was actually a little louder and as I put more tanks through the car it seemed to be getting worse again. FYI, during this time period I stayed away from SHELL station and used my normal Chevron usage except for my last tank, I happened to use another Shell station, coincidentally one that the dealer uses as well.

This last tank seemed to really get bad and basically it was back to its worst state and making the noise even louder while the car lost power during the noisy area in the tach.

Finally I couldn't take it anymore and brought the car back in, this time he ordered a fuel pump/filter and tested the fuel again. After testing the fuel pressure while driving under different loads , it tested fine. The fuel however was questionable to have too much ethanol ration again. I told him that I just filled up a the very station that they(the dealer) uses to fill up all of their cars. He then told me that he had to replace 335i injectors/fuel pump from fuel that he put in a customers car at that very station. This station happens to be a SHELL station once again. Not sure if this is coincidence are not but this worries me.

Needless to say, this service the fuel was flushed again and the fuel filter was replaced. Now the car has its power back and seems (so far) to be pulling smooth while transitioning thru the rev range BUT i still do here this noise coming from the engine. Now the tone has changed, almost like it is an induction noise are something. Really tough to tell.

I can say this though. I am VERY frustrated with these findings. I cannot believe that this car is THAT sensitive to fuel quality. This problem started when the car had about 1800 miles and at 6500 miles I finally got the car back to running with what seems like normal power levels and health, except for the noise that is still barely audible. To be honest I have driven the car in poor health more than in good health. Pretty sad really.

Granted there may be some link to QC problems with the fuel distributer for SHELL. The technician and myself have both done some research and there is a certain distributor here locally that could cause this problem with the local SHELL fuel as this ONE dist. handles all of the local SHELL stations. Proving this would be next to impossible though.

What pisses me off the most is for the last 12 years I have owned cars that required premium fuel. Porsche 911's/ Mitsu Evo/Mini Cooper S/ VW GTI/ etc. etc. and not one, ever had a problem with any of the 93 octane fuel that I used from my local area gas stations. Why now, why when I finally find the car that I really enjoy and love, would I be subjected to this BS. Not fair I tell you. I can say one thing though, if this keeps up my days will be numbered with my M3 though. Eventually this will start to hit my pocket book/ time/ and patience.

For the time being, I am really worried when it comes time to fill up my car. But I have been trying to stick to brands that I haven't had issues with yet. I will keep you posted as things develop. Hopefully this is my last time I will have this issue but I have a feeling this may be just the beginning.

[J08M3]

Thanks for the input. I haven't noticed any loss in power in my car though. I have yet to bring my car into my local dealer though as I have little faith in them figuring out what it is, if it even is something at all.

[alpineweissM3]

Originally Posted by Rovman

I have been experiencing the same noises with my car as you have. In fact, I was having a problem with my car losing performance only when the car was making that noise. Making me think it was a knocking and pinging, hence the loss in performance, as the ECU would pull(retard) timing attempting to stop the detonation.

I have to comment that my technician really worked hard on trying to fix my car. He checked the fuel quality 1st, low and behold he found a 12-14% amount of alcohol(ethanol) mixed within the fuel. He told me that the car really was not designed to run on a higher than %10 mixture of alcohol in the fuel. For clarification sake I ALWAYS run 93 octanes top tier fuels in my car. This instance I had just filled up at a local SHELL station.

Solution: he flushed the fuel and replaced it with more 93 octane and advised me to drive the car and see if it any better. Unfortunately, I drove the car for 4 more tanks worth and the car had significant power reduction, along with surging are loss of power while the slightly audible noise persisted during the 2500 - 3800 rpm rev range.

Step 2- After continued driving of the car, 4 tanks later. The car was no better. I brought the car back for service. The decision was then made to replace the injectors, under the pretense that possibly the tainted fuel could have damaged them in some way.

Solution #2: I get the car back with the injectors replaced and the car is improved but only slightly. The noise was actually a little louder and as I put more tanks through the car it seemed to be getting worse again. FYI, during this time period I stayed away from SHELL station and used my normal Chevron usage except for my last tank, I happened to use another Shell station, coincidentally one that the dealer uses as well.

This last tank seemed to really get bad and basically it was back to its worst state and making the noise even louder while the car lost power during the noisy area in the tach.

Finally I couldn't take it anymore and brought the car back in, this time he ordered a fuel pump/filter and tested the fuel again. After testing the fuel pressure while driving under different loads , it tested fine. The fuel however was questionable to have too much ethanol ration again. I told him that I just filled up a the very station that they(the dealer) uses to fill up all of their cars. He then told me that he had to replace 335i injectors/fuel pump from fuel that he put in a customers car at that very station. This station happens to be a SHELL station once again. Not sure if this is coincidence are not but this worries me.

Needless to say, this service the fuel was flushed again and the fuel filter was replaced. Now the car has its power back and seems (so far) to be pulling smooth while transitioning thru the rev range BUT i still do here this noise coming from the engine. Now the tone has changed, almost like it is an induction noise are something. Really tough to tell.

I can say this though. I am VERY frustrated with these findings. I cannot believe that this car is THAT sensitive to fuel quality. This problem started when the car had about 1800 miles and at 6500 miles I finally got the car back to running with what seems like normal power levels and health, except for the noise that is still barely audible. To be honest I have driven the car in poor health more than in good health. Pretty sad really.

Granted there may be some link to QC problems with the fuel distributer for SHELL. The technician and myself have both done some research and there is a certain distributor here locally that could cause this problem with the local SHELL fuel as this ONE dist. handles all of the local SHELL stations. Proving this would be next to impossible though.

What pisses me off the most is for the last 12 years I have owned cars that required premium fuel. Porsche 911's/ Mitsu Evo/Mini Cooper S/ VW GTI/ etc. etc. and not one, ever had a problem with any of the 93 octane fuel that I used from my local area gas stations. Why now, why when I finally find the car that I really enjoy and love, would I be subjected to this BS. Not fair I tell you. I can say one thing though, if this keeps up my days will be numbered with my M3 though. Eventually this will start to hit my pocket book/ time/ and patience.

For the time being, I am really worried when it comes time to fill up my car. But I have been trying to stick to brands that I haven't had issues with yet. I will keep you posted as things develop. Hopefully this is my last time I will have this issue but I have a feeling this may be just the beginning.

Anyone else with these issues? Mine just started doing this within the last couple weeks. Curiously, it was after the dealer had to put a new CAS module in and completely reprogram my car.

[Paddy]

I get something similar while accelerating fairly hard in second gear from a stop. Almost like the engine is laboring (like going too slow in too high a gear). I would have thought the V8 to be torquey enough to accelerate in second gear.
Maybe I need to wait till closer to redline for the 1-2 shift.

[powertrip]

I'm no stranger to "knock", as my track car was an '07 STI. With that said, I've never heard my M make any noise even resembling knock. Hopefully my Powerchip dyno tune this week will insure that I never do .

[Robo Squirrel]

mine runs kind of rough, depending on the outside temp, between 2.5k and 4k in gears 3-6...i dunno if it is b/c of the gas im using or what. I use shell normally, but i just switched to sunnoco to see if it makes any diff. I have not had any knock tho. Runs terrible on hot days with the A/C on tho.

[BPMSport]

I try to stay away from Shell gasoline as I have had bad experiences with them.

On my supercharged 330 which had 480whp, the car would ping like crazy with shell gas (first and only use). But with Chevron it was fine tank after tank.

On my friends powerchipped 335 that we tuned about 3 months ago, he ran strong with no issues until he filled up with Shell gas and went for a freeway run. The car immediately went into limp mode, and had never done this before. I had him burn that fuel off and fill up with Chevron or 76 again, and full throttle hasn't been a problem since.

Stay away from Shell! That V-Power stuff is a marketing gimic.

[Finnegan]

Originally Posted by Mike Benvo

I try to stay away from Shell gasoline as I have had bad experiences with them.

On my supercharged 330 which had 480whp, the car would ping like crazy with shell gas (first and only use). But with Chevron it was fine tank after tank.

On my friends powerchipped 335 that we tuned about 3 months ago, he ran strong with no issues until he filled up with Shell gas and went for a freeway run. The car immediately went into limp mode, and had never done this before. I had him burn that fuel off and fill up with Chevron or 76 again, and full throttle hasn't been a problem since.

Stay away from Shell! That V-Power stuff is a marketing gimic.

But I thought they had these wonderful little magic nitrogen thingies in there! And guys in lab coats say it's good!

Seriously, I concur, just couldn't resist the sarcasm about their marketing campaign.

[Robo Squirrel]

actually my buddies who all have 300hp + modded SRT-4s all have trouble with shell gas...they run like shit. The sucky thing is that its harder to find a sunnoco than it is a shell.

[PorscheRacer]

I've run Chevron and Shell routinely with no issues in the Bay Area of CA.

[alpineweissM3]

My dealer tested the fuel in my car to try and determine what is causing the knocking. They claim the Sunoco 93 that the car was filled with tested at 16% ethanol. Supposedly, this high ethanol concentration is causing the car to knock. They told me that I needed to burn that off and fill with Shell 93 and see if the car still knocks. According to my dealer, Shell doesn't use ethanol. This was backed up by the high school dropout that was working the cash register. Not sure if I believe this, but there were no ethanol disclaimers on the pumps like I have seen at other stations in my area.

[Robo Squirrel]

i think in PA, shell 93 doesnt have any ethanol, it seems that when i go home my car always runs better....coincidence?...however up here in new england, just about all gas has ethanol in it >

[J08M3]

shell 93 doesn't contain 10% (or so) Ethanol??

I've been trying different types of gas in my car - Mobil, Shell, Hess... whatever is around all 93 octane and all run exactly the same. I haven't noticed the "knock" sound recently, but I also have a much louder exhaust system on this car then when I first posted this thread.

[db1078]

I've noticed the same sound under hard acceleration about through mid range 4-6k. Sounds almost like something vibrating or rattling. Its hard to tell if the engine is running fat, knocking or such or if its a mechanical vibration. Performance is still excellent and BMW service was not able to locate the trouble. anyone else?

[Robo Squirrel]

i havent hd any knock, my car just runs shitty under certain conditions