[mhbg82]

This is my first post on this forum. Hoping to get some feedback. I unlocked my ECU on my ‘21 M4 Comp this past January. I flashed the OTS 93 stage 1 as I still have my cats. Everything felt fine. No drivability issues. About 2 weeks ago I started a custom 93 tune. First data logs went good. Nothing odd and tuner gave me more revisions. After about the fifth revision I noticed on the data log of knock detected twice on the pull. One on low load and the other through the midrange. Tuner said the fuel was the problem. I started to religiously watch the Knock Detected readout on the BM3 for multiple days. I would say knock detected gave me 1 on readout almost every few seconds. I pulled over and flashed to the OTS map. Still the same. Flashed to the CSL map. Still the same. Flashed back to stock and still had the same timely occurrence of knock detected. I decided to burn the tank off, fill up with shell 93 and had slightly better results but still had knock detected across all maps including the stock map. I added VP octane booster to 10 gallons of shell 93. That really cleaned up the logs. Timing was a lot better with all cylinders very similar to each other. I still saw knock but maybe 1 instance of 30-40 min of driving. Now that the octane boosted gas has run out the system I’ve tried to experiment with different stations and I’m finding the same result with knock. Car has 55k miles. I changed the plugs but still see knock. Not sure what else to do other than to keep adding octane booster to the tank. Any help would be appreciated. Thanks.

[mike@x-ph.com]

are you sure you are seeing a knock? did you send the logs to PTF to confirm this is a knock and not a timing correction?

[SwankPeRFection]

Plugs should be gapped to about .026. If they weren’t, you may need to pull them if they’re brand new and just recap them with a proper gapping tool. That said, with 55k miles, depending on the type of fuel you’ve pushed through the system, it might be time to change out your fuel filter. On a performance car, especially if you drive it a lot and aggressively, fuel filters should be changed even if the manufacturer doesn’t call for it. For your old plugs you pulled out, do you have pics of what they looked like? Sometimes the condition of them will tell you what might be going on. Also keep in mind that some knock can be expected from time to time, as long as it’s not extreme and as long as the timing correction associated with it isn’t by several degrees before it stops, it’s usually acceptable, especially on a factory calibration. This platform doesn’t have issues with blown intercooler cores leaking coolant into the intake tract of the engine, so something like that causing misfires is probably not your issue and if power delivery is smooth, it’s not that.

In terms of custom tunes, remote shit based on logs aren’t the best way to get a custom tune, I don’t care how long your supposed tuners has done it for. If there was knock in later revisions, then timing needed to be dialed back to give you more headroom. That said, it that tune was the problem, you would have seen an immediate improvement when running your based map and you said you didn’t. So, you’re either at fuel quality, possible dirty fuel system or something else. For now, go with either the Stage 1 OTS or the CSL map and check the gap on your plugs per what I said above. Then run a bottle of Gumout Regane (the skinny bottle) fuel system cleaner through the engine with a good tank of 93 from a reputable station. If you continue to have some issues, your next thing to swap would be your fuel filter, even from a good preventative maintenance standpoint. If you still have your old plugs, take some pics and post them if you want so we can see what they look like or even post pics of the one you have in there now that you need to take out and regap anyway.

[mhbg82]

Originally Posted by mike@x-ph.com

are you sure you are seeing a knock? did you send the logs to PTF to confirm this is a knock and not a timing correction?

I have not sent logs to PTF. Motor is running smooth all the way through out with no breakups. I’ll send them the logs and see what they say

[mhbg82]

Originally Posted by SwankPeRFection

Plugs should be gapped to about .026. If they weren’t, you may need to pull them if they’re brand new and just recap them with a proper gapping tool. That said, with 55k miles, depending on the type of fuel you’ve pushed through the system, it might be time to change out your fuel filter. On a performance car, especially if you drive it a lot and aggressively, fuel filters should be changed even if the manufacturer doesn’t call for it. For your old plugs you pulled out, do you have pics of what they looked like? Sometimes the condition of them will tell you what might be going on. Also keep in mind that some knock can be expected from time to time, as long as it’s not extreme and as long as the timing correction associated with it isn’t by several degrees before it stops, it’s usually acceptable, especially on a factory calibration. This platform doesn’t have issues with blown intercooler cores leaking coolant into the intake tract of the engine, so something like that causing misfires is probably not your issue and if power delivery is smooth, it’s not that.

In terms of custom tunes, remote shit based on logs aren’t the best way to get a custom tune, I don’t care how long your supposed tuners has done it for. If there was knock in later revisions, then timing needed to be dialed back to give you more headroom. That said, it that tune was the problem, you would have seen an immediate improvement when running your based map and you said you didn’t. So, you’re either at fuel quality, possible dirty fuel system or something else. For now, go with either the [...]

Yup power delivery feels good and smooth. I have the old plugs. I’ll get some pics and post them in here. We do have a winter blend 93 here in Michigan currently so I’m not sure if that also could be the problem.

[SwankPeRFection]

I was gonna say… winter blends are usually also to blame, so that might be it. I forget the rest of the country is still in winter when it’s 70’s where I’m at. Lol

[Dawgz]

You can't just look at the knock, you need to look at timing also.

If you see a knock and subsequently see timing drop 6° or more than there's an issue.

[mhbg82]

Originally Posted by Dawgz

You can't just look at the knock, you need to look at timing also.

If you see a knock and subsequently see timing drop 6° or more than there's an issue.

I don’t think it is based off the logs. PTF says it probably is bad fuel and that possibly my car is just more sensitive than others. he was pretty confident about me staying on the ots map. Once the fuel is sorted the custom map should be ok. Just to clarify timing looked much better with zero knock with octane booster.

[hellcat2m4]

I noticed quite a bit knock too even on the OTS ethanol maps. If you are seeing your knock not at WOT with the pedal down, disregard it. However, if you are WOT, it's possible it's a fuel issue.

[TopJimmy]

Some engine sensors are just touchy. On my F82 when I tuned heavy I would see a rare occasional knock during hard runs.

Try using 1-2gal of E85 per tank of gas instead of the octane booster, it’s much cleaner method to increase octane.

[mhbg82]

I’ve seen maybe 1 knock detected through 7-8 logs on WOT. Most of the knock I see on the BM3 is just cruising which might not be anything crazy apparently.

[MarkyB656]

Originally Posted by mhbg82

This is my first post on this forum. Hoping to get some feedback. I unlocked my ECU on my ‘21 M4 Comp this past January. I flashed the OTS 93 stage 1 as I still have my cats. Everything felt fine. No drivability issues. About 2 weeks ago I started a custom 93 tune. First data logs went good. Nothing odd and tuner gave me more revisions. After about the fifth revision I noticed on the data log of knock detected twice on the pull. One on low load and the other through the midrange. Tuner said the fuel was the problem. I started to religiously watch the Knock Detected readout on the BM3 for multiple days. I would say knock detected gave me 1 on readout almost every few seconds. I pulled over and flashed to the OTS map. Still the same. Flashed to the CSL map. Still the same. Flashed back to stock and still had the same timely occurrence of knock detected. I decided to burn the tank off, fill up with shell 93 and had slightly better results but still had knock detected across all maps including the stock map. I added VP octane booster to 10 gallons of shell 93. That really cleaned up the logs. Timing was a lot better with all cylinders very similar to each other. I still saw knock but maybe 1 instance of 30-40 min of driving. Now that the octane boosted gas has run out the system I’ve tried to experiment with different stations and I’m finding the same result with knock. Car has 55k miles. I changed the plugs but still see knock. Not sure what else to do other than to keep adding octane booster to the tank. Any help would be appreciated. Thanks.

I had a similar issue with my BM3 & OEM CSL OTS Flex Fuel all maps (all with 98 Ron OR 98 Ron + Ethanol E30 mix), although mine happens on Shift when rev's are just starting to build and the throttle is at peak closing during shift see pic again after the gear shift "sometimes" once out of 10 pulls. My car 3k miles, even the stock maps do it... so starting to think it's a false positive knock. Also whats interesting for me is that all Maps only "sometimes" knock on a shift when gearbox is set to 1, when set to 2 or 3 it never happens on ANY MAP.

So I suspect it's the slower gear change that is somehow triggering the Knock sensor maybe, as changing the gearbox shift to 2 or 3 should not make a difference in terms of a lean knock. Also never happens at mid or top end RPM of a pull.

My pull with CSL Map and 98RON & E30 mix in tank.
https://www.bootmod3.net/log?id=65e4...912436fb2fdada

[SwankPeRFection]

Why are you running a CSL calibration with E30 mix? There’s enough headroom in stock fueling for E20ish safely, but CSL is already pushing more boost than a base map and thus already asking for more fuel from same injectors. Lower overhead from that + lower overhead from you running E30 mixes. Do you have this problem when you’re not running E at all?

[MarkyB656]

Originally Posted by SwankPeRFection

Why are you running a CSL calibration with E30 mix? There’s enough headroom in stock fueling for E20ish safely, but CSL is already pushing more boost than a base map and thus already asking for more fuel from same injectors. Lower overhead from that + lower overhead from you running E30 mixes. Do you have this problem when you’re not running E at all?

I'm running BM3 FlexFuel kit, it dynamically changes the Map when you add Ethanol (timing and boost etc) depending on the % of Ethanol it detects, thats the whole idea, anyhow it happens with just plain 98 RON (93 Octane) as well as I said in my post, so thats 100% stock OEM CSL tune also doing the same thing.

https://www.protuningfreaks.com/prod...39961406177329

[markoz28]

Originally Posted by MarkyB656

I'm running BM3 FlexFuel kit, it dynamically changes the Map when you add Ethanol (timing and boost etc) depending on the % of Ethanol it detects, thats the whole idea, anyhow it happens with just plain 98 RON (93 Octane) as well as I said in my post, so thats 100% stock OEM CSL tune also doing the same thing.

https://www.protuningfreaks.com/prod...39961406177329

Im confused. Are you saying that your CSL map is also a flex tune map? I dont believe that is how it works. I think a CSL map is just that, one type of tune with no scaling.

[81bear]

Originally Posted by markoz28

Im confused. Are you saying that your CSL map is also a flex tune map? I dont believe that is how it works. I think a CSL map is just that, one type of tune with no scaling.

No all 4 maps are flex fuel enabled.

[MarkyB656]

Originally Posted by 81bear

No all 4 maps are flex fuel enabled.

Correct, thanks for answering for me

[mhbg82]

Well after going through the whole car, everything checks out. Car runs strong, idles perfect. No more knock. Now my only problem is that the tuner is saying he can’t push any further bc of the low quality fuel. As of right now the custom tune is as fast or slower than the OTS 93 map. Is anyone else running a custom 93 tune in the Midwest with this issue?

[hellcat2m4]

Originally Posted by mhbg82

Well after going through the whole car, everything checks out. Car runs strong, idles perfect. No more knock. Now my only problem is that the tuner is saying he can’t push any further bc of the low quality fuel. As of right now the custom tune is as fast or slower than the OTS 93 map. Is anyone else running a custom 93 tune in the Midwest with this issue?

Sounds like a Cary Jordan/Jordantuned excuse. If so, I would find a different tuner.

[mhbg82]

Originally Posted by hellcat2m4

Sounds like a Cary Jordan/Jordantuned excuse. If so, I would find a different tuner.

I don’t know man. This tuner is one of the best around. Tunes all the world record cars. There’s a noticeable difference between the custom tune and the OTS. I’m RWD so on the custom map I get tons of wheel spin on a 50 roll. The OTS maybe slipped a tiny bit. Best 60-130 on custom map is 7.47 and the best OTS 93 is 7.44. I’m gonna try some dragy runs today and tomorrow. Should be better with temps rising. I’m on BMW star PS4S.

[SwankPeRFection]

Who’s the tuner?

[mhbg82]

Sameh is the tuner