[andyho123]

Could you guys help me diagnose this superknock codes? Car is stock tune with catless downpipes. Car runs fine and idle fine

[vasillalov]

So let me get this straight... You have catless downpipes and stock software AND you are wondering why tge engine is throwing codes at you?...

[andyho123]

Look at the codes…referring to superknock code

[vasillalov]

I am looking at the codes and my rhetorical question still stands. Let me give you another one: do you honestly believe that with catless downpipes you will only get 18001 and 180101 codes and nothing else? You are messing with the air to fuel ratio as the dme is struggling to adapt to the new readings from the 02 sensors and it us clearly failing. Your car is NOT running fine at all. Definitely not under load.

[andyho123]

Lol ok Mr. Expert so what’s wrong with my car then ? I haven’t seen anywhere that say I need tunes for catless dp.

[Indo Rider]

Originally Posted by andyho123

Lol ok Mr. Expert so what’s wrong with my car then ? I haven’t seen anywhere that say I need tunes for catless dp.

I tend to agree. Plenty of people running piggybacks like jb4 or race chip with catless downpipes and those are not really doing a whole lot besides raising/controlling the boost. Maybe car is over boosting, due to the lesser restriction allowing turbos to spool faster and the car isn't adapting to that yet? What are you reading codes with? Can you do some data logging to see what's going on when the codes are thrown? Also why not go ahead and at least get a jb4 so you can really take advantage of the bolt on parts?

[Indo Rider]

Originally Posted by vasillalov

I am looking at the codes and my rhetorical question still stands. Let me give you another one: do you honestly believe that with catless downpipes you will only get 18001 and 180101 codes and nothing else? You are messing with the air to fuel ratio as the dme is struggling to adapt to the new readings from the 02 sensors and it us clearly failing. Your car is NOT running fine at all. Definitely not under load.

Do we know for sure that the post cat O2 sensors are really used for AFR control. I know these engines are fancy, but that should primarily be based on pre cat sensors, no?

[andyho123]

Originally Posted by Indo Rider

I tend to agree. Plenty of people running piggybacks like jb4 or race chip with catless downpipes and those are not really doing a whole lot besides raising/controlling the boost. Maybe car is over boosting, due to the lesser restriction allowing turbos to spool faster and the car isn't adapting to that yet? What are you reading codes with? Can you do some data logging to see what's going on when the codes are thrown? Also why not go ahead and at least get a jb4 so you can really take advantage of the bolt on parts?

Hey, I know tunes would maximize the benefits of the downpipes but I’m not exploring that route at the moment. I have never seen these superknock codes before

[Indo Rider]

Originally Posted by andyho123

Hey, I know tunes would maximize the benefits of the downpipes but I’m not exploring that route at the moment. I have never seen these superknock codes before

Well fine, but you're not really going to be able to get much help without being willing to share more information or provide some logs of what's going on to provide context. Help us help you.

[andyho123]

Originally Posted by Indo Rider

Do we know for sure that the post cat O2 sensors are really used for AFR control. I know these engines are fancy, but that should primarily be based on pre cat sensors, no?

Whst do you mean? That’s literally all I have. I read codes with BimmerLink app, it’s just a code reader. Car is stock tune. There’s no mods Beside dp and exhausts..

[andyho123]

I can’t log when I’m not tune. What do I even log with

[Indo Rider]

Originally Posted by andyho123

Whst do you mean? That’s literally all I have. I read codes with BimmerLink app, it’s just a code reader. Car is stock tune. There’s no mods Beside dp and exhausts..

That's a start... Did you get the super knock codes exactly once? Or have you cleared the codes and they come back multiple times? Did car go into limp mode when the codes popped? Did they happen immediately after installing down pipes or did you run the down pipes for a while without getting super knock codes? Context my man.

[LongBeachDinanFan]

It means you have major knock and tuned it too aggressive.

[andyho123]

Lol idk how many times I have to say this car is stock. You want me to tell bmw they tuned it to agressive? Lol

[andyho123]

Originally Posted by Indo Rider

That's a start... Did you get the super knock codes exactly once? Or have you cleared the codes and they come back multiple times? Did car go into limp mode when the codes popped? Did they happen immediately after installing down pipes or did you run the down pipes for a while without getting super knock codes? Context my man.

Didn’t know that’s what you were referring to. My bad. Nah I have had it for a while now. Car never go into limp mode. I usually go in and clear my CEL when it pops up. This is first time I see this code. I haven’t cleared it and re run yet. I did get the downpipes adjusted recently for clearances but that’s it. Code popped up next morning. My guess maybe o2 Is damsged? But i believe that would be a whole set of other codes

[LongBeachDinanFan]

Originally Posted by andyho123

Lol idk how many times I have to say this car is stock. You want me to tell bmw they tuned it to agressive? Lol

I didn't read all the post. Then something is wrong, take your stock car to the dealer to fix it.

[andyho123]

Just trying to get insights from here. Car is at dealer. Just in case they give me some bs answers

[Indo Rider]

Originally Posted by andyho123

Didn’t know that’s what you were referring to. My bad. Nah I have had it for a while now. Car never go into limp mode. I usually go in and clear my CEL when it pops up. This is first time I see this code. I haven’t cleared it and re run yet. I did get the downpipes adjusted recently for clearances but that’s it. Code popped up next morning. My guess maybe o2 Is damsged? But i believe that would be a whole set of other codes

Well if you already have it at dealer then maybe they can tell you something. What type of fuel? Did you just fill up recently? Maybe bad gas? Were you lugging it at super low rpms WOT? Could be a real problem, might be a fluke.

[andyho123]

Yeah have a thought that it might be a bad batch of gas. I pumped it at another station that I don’t usually go to. I did several highway pulls 4k n up. Guess I’ll wait and see what’s up with it. Just funny that this code doesn’t throw it into limp mode

[vasillalov]

Originally Posted by Indo Rider

Do we know for sure that the post cat O2 sensors are really used for AFR control. I know these engines are fancy, but that should primarily be based on pre cat sensors, no?

Yes they are. Post cat O2 sensors are used for adjusting LTFTs at the least.

[ZheroG80]

I am going to say your cars fuel trims are most likely way off based on the catless DP's and no tune. These new DME's are no joke, every car is different as well. My car may run them fine while yours may not, but the readings from the o2 sensor may be triggering your DME to throw this code.

Possible fix/trick may be o2 spacers to trick them to think it has cats on it still.

[Indo Rider]

Originally Posted by vasillalov

Yes they are. Post cat O2 sensors are used for adjusting LTFTs at the least.

Ok, but won't the car adjust short term fuel trims to hit proper AFR and then eventualy learn to correct the long term trims based on always having to adjust the short term trims? How does a JB4 account for catless downpipes? Plenty people have catless downpipes with JB4 or race chip and no such issues.

I'm just genuinely interested to understand these things better for S58 since not many people here talk technical details, it all just exhaust and front lips.. lol.