[msk340i]

I got a torque limitation due to super knock and knock on 3 cylinders. Codes 152108 152208 152308 152F08. Car is sluggish. Barely moving. Transmission changes are weird.
Next step?
P.S. car is 340i stage 2 bm3 with high flow cat.

[G.Newt]

Have you changed the spark plugs?

[msk340i]

Originally Posted by G.Newt

Have you changed the spark plugs?

Yes

[RMMAGA]

I got this SR issue on my B48 on gear changes at high RPM and high load, like 7000rpm and 220 - 230 load (25-27 psi), see if you can see it in the logs, if it only happens on gear changes it may not be as serious as if it happens during a pull, however if it does throw a code it is pretty major, there are different levels of SR, a little bit and it will just reduce loads a little, a big one and it will pull a lot of load and eventually throw a code

FYI I also have a "high flow" cat

SR is knock detected that is not just after to a ignition event like normal knock, like pre ignition would be, my theory is that some back fires during the shits may be causing this to false trigger on gear shifts, as it did tend to happen when there were some back fires on the shit, but really I have no idea

note I ended up disabling all TQ load limit due to super knock (SR) in the tune, so if this happens during a pull I can still get full power, however this may not be the best or safe solution, it was just frustrating and I couldn't figure out how to fix it

[Tmck]

Originally Posted by RMMAGA

I got this SR issue on my B48 on gear changes at high RPM and high load, like 7000rpm and 220 - 230 load (25-27 psi), see if you can see it in the logs, if it only happens on gear changes it may not be as serious as if it happens during a pull, however if it does throw a code it is pretty major, there are different levels of SR, a little bit and it will just reduce loads a little, a big one and it will pull a lot of load and eventually throw a code

FYI I also have a "high flow" cat

SR is knock detected that is not just after to a ignition event like normal knock, like pre ignition would be, my theory is that some back fires during the shits may be causing this to false trigger on gear shifts, as it did tend to happen when there were some back fires on the shit, but really I have no idea

note I ended up disabling all TQ load limit due to super knock (SR) in the tune, so if this happens during a pull I can still get full power, however this may not be the best or safe solution, it was just frustrating and I couldn't figure out how to fix it

Has the problem been resolved? Im currently having this issue

[IMS-340C]

Got the same code a while ago on OEM MPPSK tune.

Not sure what caused this code, either bad fuel the petrol station or high torque for the weather as it's getting really hot here 35+ Celsius.

I drove really slow till I emptied the tank, changed the petrol station and also reduced torque from 500 nm to 460 nm.

I also reduced maximum load from 185 to 175.

Car is driving normally now never noticed anything strange till now.

EDIT: I am also suspecting this happening as a result of a boost spike especially with high flow/Catless downpipe the turbo spools much faster as a result of the higher flowing exhaust.

[Wires]

High outside temperatures (IE high IAT) coupled with a bad batch of fuel (low octane) can do this.

The "knocking" is pre-ignition where the cylinder is lighting earlier than expected during the upstroke which tries to push the cylinder back down the wrong way (exploding on the upstroke instead of the downstroke). Cooler intake temps, humidity, and higher octane slows the burn which addresses this.

[Tmck]

Originally Posted by Fuel-It!

Looks at your knock levels in a log carefully as super knock faults are bad news. You might need less timing or more octane for your target boost levels.

Originally Posted by IMS-340MP

Got the same code a while ago on OEM MPPSK tune.

Not sure what caused this code, either bad fuel the petrol station or high torque for the weather as it's getting really hot here 35+ Celsius.

I drove really slow till I emptied the tank, changed the petrol station and also reduced torque from 500 nm to 460 nm.

I also reduced maximum load from 185 to 175.

Car is driving normally now never noticed anything strange till now.

EDIT: I am also suspecting this happening as a result of a boost spike especially with high flow/Catless downpipe the turbo spools much faster as a result of the higher flowing exhaust.

Originally Posted by Wires

High outside temperatures (IE high IAT) coupled with a bad batch of fuel (low octane) can do this.

The "knocking" is pre-ignition where the cylinder is lighting earlier than expected during the upstroke which tries to push the cylinder back down the wrong way (exploding on the upstroke instead of the downstroke). Cooler intake temps, humidity, and higher octane slows the burn which addresses this.

Originally Posted by Fuel-It!

Looks at your knock levels in a log carefully as super knock faults are bad news. You might need less timing or more octane for your target boost levels.

So im running the Stage 2 93 tune in Georgia. And the problem did start for after running the 93. So basically if i flash back to Stage 2 91, and still use 93 octane will it be enough to hit target boost?

[kriszty]

Originally Posted by Tmck

So im running the Stage 2 93 tune in Georgia. And the problem did start for after running the 93. So basically if i flash back to Stage 2 91, and still use 93 octane will it be enough to hit target boost?

yes

[Tmck]

Originally Posted by kriszty

yes

Ok will flash back and provide an update.
Also planning to replace spark plugs and ignition coils

[IMS-340C]

Damn got the super knock code again it's really frustrating.

As you see guys in the attached photo and log when I floor it between 2.5-4K RPM I always get this boost spike, I am sure this is what causing the super knock code.

And that was on a very conservative tune with only 460 nm of torque request.

Log here : https://datazap.me/u/ims/ims-mppsk-4...og=0&data=4-16

[luchocamp]

Originally Posted by Fuel-It!

Looks at your knock levels in a log carefully as super knock faults are bad news. You might need less timing or more octane for your target boost levels.

agree

[IMS-340C]

Lower timing only lesser the problem as it prevents 2 or more combustion to collide at the sane time.

If fuel is pre igniting then the solution would be using higher octane (if available) or using less torque request in the tune.

[XutvJet]

Perhaps this goes without saying, but super knock is VERY bad. It's also known as low speed pre-ignition (LSPI). It's a somewhat new phenomenon that occurs in modern direct injection (DI) motors. It's a factor of a lot things like DI, quick spooling turbos, high compression ratios (thanks to DI), variable valve timing, oil residual in the combustion chamber from the EVAP system, etc. Basically, we have turbo motors that can now deliver a lot power from a very low rpm all through the top end. This wasn't the case prior to the mid-2000s or so.

LSPI tends to happen in low rpms with heavy throttle or what is known as high load. If you mash the gas in 4th at 2000rpms, this puts heavy load on the motor and the turbo spools extremely fast. This can cause overboost and the boost can happen so fast that the engine computer's safeguards (timing cut, increase A/F ratio, slam throttle shut) can't catch it fast enough to stop LSPI.

What can just a little LSPI do? Bend a rod, break a piston ring land, spin a rod bearing because the LSPI hammered hammered the piston and rod so hard that protective oil film between the rod bearing and crank was squeezed out. I also wonder if LSPI might cause scoring of the cylinder walls in the B58s. Just 1 second LSPI event can be bad enough to wreck a motor. Luckily, BMW makes a pretty stout short block, but when you're pushing way more power than stock, all bets are off because you're operating the motor in a range it wasn't intended.

[Tmck]

Originally Posted by Tmck

Ok will flash back and provide an update.
Also planning to replace spark plugs and ignition coils

Flashed back to bm3 stg2 91 while still using 93octane but problem still remains. What octane boosters would anyone recommend? Any other solutions?
Still haven't replaced spark plugs or coils yet

[_N54]

Super knock is not a good fault code. People have found internal damage in the N54 scene with super knock faults. Get it checked out by a shop ASAP.

[msk340i]

Ok everyone. Thank you for all the suggestions. After spending a lot of money trying to figure it out it turned out that the cat came loose and was blocking the downpipe. Stupid problem and stupid mechanic and stupid me.

[Wires]

At least you found it. Making lemonade when the world tosses you lemons.

[IMS-340C]

Yeah mate I know I am totally avoiding any hard acceleration though the problem only occurs at initial acceleration even timing correction are close to zero near redline.

Even if I floor it from standstill it runs normally no fault codes, it only happens at full throttle at 4th or 5th gear between 2500-4000 RPM.

The car is still under warranty but I can't take to BMW as it has a catless downpipe.

I am thinking of putting back the stock catted downpipe and see if it solves the problem.

Thanks

Originally Posted by 6266N54

Super knock is not a good fault code. People have found internal damage in the N54 scene with super knock faults. Get it checked out by a shop ASAP.

[kriszty]

Originally Posted by Tmck

Flashed back to bm3 stg2 91 while still using 93octane but problem still remains. What octane boosters would anyone recommend? Any other solutions?
Still haven't replaced spark plugs or coils yet

try to add some ethanol 100% ( 3 or 4 liters at full tank ) octane boosters i should not use it for long term

[XutvJet]

Originally Posted by IMS-340MP

Even if I floor it from standstill it runs normally no fault codes, it only happens at full throttle at 4th or 5th gear between 2500-4000 RPM.

This is the very situation I'm talking about regarding LSPI. High load, low rpm.

Definitely swap the stock DP back in and see if it remedies the issue. Your tune may be too aggressive for the climate, altitude, and octane you're running. Dial it back and stop going full throttle from 2500rpms in the taller gears. Downshift if you need the passing power.

[Info@mad-us.com]

Originally Posted by IMS-340MP

Damn got the super knock code again it's really frustrating.

As you see guys in the attached photo and log when I floor it between 2.5-4K RPM I always get this boost spike, I am sure this is what causing the super knock code.

And that was on a very conservative tune with only 460 nm of torque request.

Log here : https://datazap.me/u/ims/ims-mppsk-4...og=0&data=4-16

Your running 88 octane based on your sig?