Knock Detected BM3

[BruskSeeKShots]

Hello everyone hope all is well. I have noticed that after data logging my car I get a knock event at WOT sometimes and sometimes not. I have been data logging for a while and have not had knock events until now. I have also noticed a knock event being shown in just daily driving. My car has been running rougher lately and has been causing my AFRs and STFT to increase when driving around the city, however, they do clean up when I am under load. I am wondering if one of you can look at my data logs and see what is potentially causing the knock event to be recorded as I can not seem to find what is going on. I am currently running, catless DP's, single mid pipe, NGK 97506 gapped to 0.22, BMS intakes, upgraded charge pipes, a bm3 flex fuel sensor, and running a flex fuel stage 2 multimap of about e30. I have posted a log below of a WOT pull from 3rd to 6th gear. Thanks!
Datazap: https://datazap.me/u/bruskseekshots/...m3?log=0&data=

[n8dgr84]

I would run a bottle of Techron or Redline injector cleaner and report back.
If no change, use the F8S plugs.
Your engine isn't in imminent danger. Seems almost like a ghost knock with very little correction.

[Jaizero]

You need to start your log in 3rd gear around 2500 RPM and throttle to 100% all the way out to 6800 RPM with DSC fully off. You are rolling into the throttle at the beginning of your log.

I don't see any knock in this log.

Ignition timing looks pretty good with only a few corrections.
Wastegate duty cycle looks good.
Load actual vs load target is a bit off but that may be due to the timing corrections (among a million other things lol).

The log looks pretty good, looks similar to mine running basically the same setup @ E30 minus the downpipes and single mid. I'm guessing you are at a lower elevation than me as your WGDC is a few percent lower than mine, downpipes and single mid are probably helping with that, too.

Knock at cruise is pretty common, and even happens on the stock map. I wouldn't worry about that.

[BruskSeeKShots]

Originally Posted by n8dgr84

I would run a bottle of Techron or Redline injector cleaner and report back.
If no change, use the F8S plugs.
Your engine isn't in imminent danger. Seems almost like a ghost knock with very little correction.

Okay thanks for the info, I am going to run a bottle of hotshot gasoline extreme as some other forum members said it’s a great fuel system cleaner and I will report back

[BruskSeeKShots]

Originally Posted by Jaizero

You need to start your log in 3rd gear around 2500 RPM and throttle to 100% all the way out to 6800 RPM with DSC fully off. You are rolling into the throttle at the beginning of your log.

I don't see any knock in this log.

Ignition timing looks pretty good with only a few corrections.
Wastegate duty cycle looks good.
Load actual vs load target is a bit off but that may be due to the timing corrections (among a million other things lol).

The log looks pretty good, looks similar to mine running basically the same setup @ E30 minus the downpipes and single mid. I'm guessing you are at a lower elevation than me as your WGDC is a few percent lower than mine, downpipes and single mid are probably helping with that, too.

Oh okay I see, yea I did roll into it a bit as the conditions weren’t the best and wanted to minimize spinning, I will do another log today and post it. The knock events appear at around 5k rpm and 5500 rpm in the log. If you just only have the knock detected checked and nothing else it shows in the datazap, but I don’t see any odd balls in the rest of the log that can lead up to that knock so I am kinda stumped

[Jaizero]

I don't see anything glaring on the knock events. There's a bit of timing correction during the events, but nothing too drastic.

What is your base fuel and what map slot are you using?

[BruskSeeKShots]

Originally Posted by Jaizero

I don't see anything glaring on the knock events. There's a bit of timing correction during the events, but nothing too drastic.

What is your base fuel and what map slot are you using?

Base fuel as in what I’m running? I’m running e30 (e85 and 91 blended) and am on the stage 2 flex fuel multi map by bm3, currently on map switcher 1 of 4 which is same power just no burbles

[Jaizero]

Your base fuel is 91ACN since you are in California, that is what I was asking.

Slot 1 is for 91ACN so you're in the right slot.

This is more than likely an octane issue, fuel in California SUCKS for whatever reason. That is why there is a 91 tune and a 91ACN tune specifically for people in Arizona, California, and Nevada.

Stay in slot 1 but up your ethanol content to E35 or E40 and relog.

[BruskSeeKShots]

Originally Posted by Jaizero

Your base fuel is 91ACN since you are in California, that is what I was asking.

Slot 1 is for 91ACN so you're in the right slot.

This is more than likely an octane issue, fuel in California SUCKS for whatever reason. That is why there is a 91 tune and a 91ACN tune specifically for people in Arizona, California, and Nevada.

Stay in slot 1 but up your ethanol content to E35 or E40 and relog.

Oh okay yea I am on the ACN 91 slot but I thought that slot does not matter as I am using the flex fuel sensor? I will try e40 and see if it logs any better. Do you think getting a proper (not kill map) custom tune would be worth it for the long run? I feel like these OTS maps are not refined enough for everyone as every car is different.

[Jaizero]

It absolutely does matter.

E30 with a 91 base has less octane than E30 with a 93 base.

Let's assume your E85 has an octane rating of 100, and you're using 91 as a base.

At E30 your octane rating will be around 94.3

Now let's assume your E85 has an octane rating of 100, but your base fuel is 93.

At E30 your octane rating becomes 95.5.

The octane rating of your E blend is dependent on several factors including the octane of your E85 (which may or may not actually be E85) and the octane of your base fuel (which may or may not actually be the advertised octane. In CA your 91 is probably anywhere between 87-90 or even lower).

The stage 2 flex multimap really needs a 96 octane or better for no timing corrections in my experience.

[Jaizero]

You could also drop down to the stage 1 multimap in slot one and relog to see if the knock and timing corrections clear up. Log several pulls as the DME will need time to readapt after flashing the new tune.

[BruskSeeKShots]

Originally Posted by Jaizero

It absolutely does matter.

E30 with a 91 base has less octane than E30 with a 93 base.

Let's assume your E85 has an octane rating of 100, and you're using 91 as a base.

At E30 your octane rating will be around 94.3

Now let's assume your E85 has an octane rating of 100, but your base fuel is 93.

At E30 your octane rating becomes 95.5.

The octane rating of your E blend is dependent on several factors including the octane of your E85 (which may or may not actually be E85) and the octane of your base fuel (which may or may not actually be the advertised octane. In CA your 91 is probably anywhere between 87-90 or even lower).

The stage 2 flex multimap really needs a 96 octane or better for no timing corrections in my experience.

Ahhhh I see okay so I really should try bumping up my octane since you said you notice it runs best at 96. I am going to first cycle a tank of pump gas and add the injector cleaner as people said it does not mix well with ethanol and then fill up on e40 next time and see how it runs. Thank you for the help!

[Jaizero]

Shoot for E43 or so to get to 96 octane.

[BruskSeeKShots]

Originally Posted by Jaizero

Shoot for E43 or so to get to 96 octane.

Got it, I also ordered an amazon tester to test the ethanol content. The gas station that carries our ethanol is only local and has one location and I have been mixing their pump gas with their ethanol but maybe their pump gas is terrible quality. If their ethanol is good, I may head to the shell across the street to fill up on their 91 first then go straight to the e85 station to fill with the remaining ethanol. Since I have flex fuel I can do that correct? I will just fill with pump first so I am not driving on only ethanol.

[BruskSeeKShots]

Originally Posted by Jaizero

Shoot for E43 or so to get to 96 octane.

I also think that ever since I got these “cold air” aka hot air open filter BMS intakes I have been having some issues. My afrs and stfts fluctuate like crazy in city driving, like hitting 16-17 afr and a 1.15 stft. Maybe the maf sensors are dirty as well. Should I swap out for the stock intakes?

[Jaizero]

Originally Posted by BruskSeeKShots

I also think that ever since I got these “cold air” aka hot air open filter BMS intakes I have been having some issues. My afrs and stfts fluctuate like crazy in city driving, like hitting 16-17 afr and a 1.15 stft. Maybe the maf sensors are dirty as well. Should I swap out for the stock intakes?

The stock intakes are best. 16-17 AFR is very lean unless you have your foot off the pedal lol

[Jaizero]

I wouldn't worry too much about what the STFTs are doing by themselves. You need to look at both Long term and short term fuel trims in both banks.

[BruskSeeKShots]

Yea thats what im confused about. Here is a 70 second datalog of me just driving around the city and you can see my AFR jumping to 18 at one point and just overall fluctuating a lot. I also noticed that if I very gently apply the throttle at around 1.5-2k rpm and hold it the car starts misfiring like crazy and I can physically feel the car shake. I get no codes however and have used bootmod, bimmerlink, and even ista to see if any hidden codes are stored and no codes are detected. I am just confused about why it drives so poorly in low-throttle applications, but once there is a load on the engine the issues seem to disappear!
Datazap: https://datazap.me/u/bruskseekshots/...g?log=0&data=7

[Jaizero]

Originally Posted by BruskSeeKShots

Yea thats what im confused about. Here is a 70 second datalog of me just driving around the city and you can see my AFR jumping to 18 at one point and just overall fluctuating a lot. I also noticed that if I very gently apply the throttle at around 1.5-2k rpm and hold it the car starts misfiring like crazy and I can physically feel the car shake. I get no codes however and have used bootmod, bimmerlink, and even ista to see if any hidden codes are stored and no codes are detected. I am just confused about why it drives so poorly in low-throttle applications, but once there is a load on the engine the issues seem to disappear!
Datazap: https://datazap.me/u/bruskseekshots/...g?log=0&data=7

Go back to the stock intakes, I bet your problem goes away.

I also bet your long term fuel trims are fu@ked lol

[BruskSeeKShots]

Originally Posted by Jaizero

Go back to the stock intakes, I bet your problem goes away.

I also bet your long term fuel trims are fu@ked lol

lol that’s concerning, do you think this has caused a detrimental effect on the engine? Is there any way to check LTFT? If say changing the intakes and fueling fixed the issues would my LTFT be fixed? I’m still learning about all the terms so I had to google what long term fuel trims are since I only know what the short term fuel trim is haha

[Jaizero]

Originally Posted by BruskSeeKShots

lol that’s concerning, do you think this has caused a detrimental effect on the engine? Is there any way to check LTFT? If say changing the intakes and fueling fixed the issues would my LTFT be fixed? I’m still learning about all the terms so I had to google what long term fuel trims are since I only know what the short term fuel trim is haha

You log LTFT the same as STFT, you need to enable it in the BM3 dashboard settings.

Make sure to look at both banks.

Essentially what you want to do is add the LTFT and STFT together to see overall trims.

If LTFT is 1.05 and STFT is 1.15, the overall would be 1.2 (This is very bad and can throw a code).

If LTFT is 0.95 and STFT is 1.15, then the overall is 1.10.

You want to be 1.0 +- 5% in both banks usually. The stage 2 flex multimap runs rich for me so my LTFTs are around 0.93-1.0.

Don't worry too much if both banks aren't the same. A large discrepancy between banks (more than 4 or 5%) might be something to look into.

High positive fuel trims (DME adding fuel) are indicative of vacuum leaks, boost leaks, failing fuel pumps, failing O2 sensors, etc.

High negative fuel trims (DME removing fuel) are indicative of leaky injectors, clogged intake filters, failing O2 sensors, etc.

[BruskSeeKShots]

Originally Posted by Jaizero

You log LTFT the same as STFT, you need to enable it in the BM3 dashboard settings.

Make sure to look at both banks.

Essentially what you want to do is add the LTFT and STFT together to see overall trims.

If LTFT is 1.05 and STFT is 1.15, the overall would be 1.2 (This is very bad and can throw a code).

If LTFT is 0.95 and STFT is 1.15, then the overall is 1.10.

You want to be 1.0 +- 5% in both banks usually. The stage 2 flex multimap runs rich for me so my LTFTs are around 0.93-1.0.

Don't worry too much if both banks aren't the same. A large discrepancy between banks (more than 4 or 5%) might be something to look into.

High positive fuel trims (DME adding fuel) are indicative of vacuum leaks, boost leaks, failing fuel pumps, failing O2 sensors, etc.

High negative fuel trims (DME removing fuel) are indicative of leaky injectors, clogged intake filters, failing O2 sensors, etc.

Got it, well I just check my bootmod3 app and I don’t even have an option for the long term fuel trim readings, I scrolled through the entire option of data to read and I only have STFT