Finding of limits of 540i Supercharged with superbad gasoline...

[geargrinder]

Simple example: let's assume, knocking started in 5500rpm and continued to 7000rpm. Engine blown. My question is, why my ECU does not stop knocking when it is just started at 5500rpm? Why is it not cut fuel as when knocking appear? If it is detect and react very well, I should not get engines burnt.

What tune is it that you were on when that happened? ME7 has plenty sophisticated knock sensing logic absolutely. However, it could very well be that the amount of boost+lousy-gas you poured into the motor was far beyond what the design parameters where. The factory calibration is designed to pull some ignition for normal, not-modded, no-boost situation. Indeed if you were jacking WOT with terrible gas and super high intake temps, and lotta boost, well, what is "plenty ignition pull" for a stock car could indeed be inadequate response for yours.

I also agree w/ Thad - the best knock prevention is not getting into knock in the first place! It really should be a "rare malfunction" feature, not a 'bounce off the knock sensors all the time" situation.

That said, some engines - like the S54 - come with factory calibrations that are super conservative for knock and will keep timing way down. One of the first thing any S54 tuner does is to pull the knock limits up and add timing... However that's all based on careful evaluation of that engines operating behavior, and usually entails telling owners "OK this is a 93 Octane tune ONLY..."

Again - not arguing that if you want a big-boost build and have challenging situation (BTW, also I am sure your hot ambient temperatures are ADDING to your gas problems...) that a standalone isn't a good option.

I'm only arguing your suggestion that for EVERYONE stock ECU's can NEVER work for F/I engines.

That is especially NOT true for stock ECU's that are 1. well mapped/understood (and of course I completely agree w/ you that ME7 ... and 5 for that matter... are WAY underdocumented...), or 2. factory-boost ECU's.

ME7 is used on a bunch of boosted cars, just not BMW ME7... Audi's ME7.1 is super well understood and guys have been making tons of power happily and safely on that ECU for almost 20yrs. Even the E36 guys know how to make great power on non-F/I BMW ECU's safely.

[dovlet]

It is an extremely nice attribute of standalone ECUs that you can configure the parameters the way you want them, such as how it deals with knock as you mention. But to be honest, I never want to rely on knock control strategies from the ECU (just my personal preference), so I don't have much experience with the methods used by the different standalones. Which ECU are you planning to use, and what does it allow you to have it do when the ECU senses knock?

That is invent EMS2. It has plenty controlling options not only knocking. Knocking is the last control element on engine safety, prior to that engine EGT, temperatures, AFR, Cooling air, & ETC.

I believe that with factory ECUs such as the ME7.2, when they are well enough understood for us to be able to tune them, we are limited to amount of spark advance pulled when knock is sensed, and the length of time after knock stops before the timing advance is added back in. It should usually be a sufficient strategy to keep the engine safe if you have tuned it well, but the trick is to know where all of the various tables are that may have hidden effects on actual spark advance outputted to the engine. And then if the ECU is protecting the engine in that way, it is creating horrendously high temperatures in the exhaust system...

But that goes back to why I say I don't really want the ECU keeping my engine from knocking. I just want to keep my engine from knocking in the first place. For you that means water injection, or water/vodka injection. You don't really have another good choice.

Believe me, ME7.2 is not preventing trouble. Perhaps safety table exists somewhere inside of ECU, but it does not work and that is proven. If stock ECU is so good, then we probably never hear about Motec, MS, AEM, etc etc etc.

[dovlet]

What tune is it that you were on when that happened? ME7 has plenty sophisticated knock sensing logic absolutely. However, it could very well be that the amount of boost+lousy-gas you poured into the motor was far beyond what the design parameters where. The factory calibration is designed to pull some ignition for normal, not-modded, no-boost situation. Indeed if you were jacking WOT with terrible gas and super high intake temps, and lotta boost, well, what is "plenty ignition pull" for a stock car could indeed be inadequate response for yours.

I also agree w/ Thad - the best knock prevention is not getting into knock in the first place! It really should be a "rare malfunction" feature, not a 'bounce off the knock sensors all the time" situation.

That said, some engines - like the S54 - come with factory calibrations that are super conservative for knock and will keep timing way down. One of the first thing any S54 tuner does is to pull the knock limits up and add timing... However that's all based on careful evaluation of that engines operating behavior, and usually entails telling owners "OK this is a 93 Octane tune ONLY..."

Again - not arguing that if you want a big-boost build and have challenging situation (BTW, also I am sure your hot ambient temperatures are ADDING to your gas problems...) that a standalone isn't a good option.

I'm only arguing your suggestion that for EVERYONE stock ECU's can NEVER work for F/I engines.

That is especially NOT true for stock ECU's that are 1. well mapped/understood (and of course I completely agree w/ you that ME7 ... and 5 for that matter... are WAY underdocumented...), or 2. factory-boost ECU's.

ME7 is used on a bunch of boosted cars, just not BMW ME7... Audi's ME7.1 is super well understood and guys have been making tons of power happily and safely on that ECU for almost 20yrs. Even the E36 guys know how to make great power on non-F/I BMW ECU's safely.

I was on stock & tuned as well. Both of then blown my engine.
I am not considering knocking as a primary method. Prior to knocking there will be engine EGT & temperature increasing.
I said, stock ECU is not good for Forced Induction.

[tptrsn]

I think we are all in agreement that a standalone can usually be easier to have a good forced induction result with than a factory ECU that was intended for a normally aspirated application.

But still, MANY MANY people make BIG power on factory ECUs without blowing up engines, especially in the E36 world (since we are discussing BMWs). Many of the guys using factory DMEs for forced induction in E36s would argue against you that the DME is far better for forced induction than a standalone, and their excellent results make it difficult to argue.

When it comes to E39s though, the DMEs don't play very nicely with forced induction because they are not well understood by us end users.

Remember though, a stadalone ECU is just a tool, and it will do whatever you tell it. A well-done engine tune is critical to a good outcome, whether you have engine-protecting features in the ECU or not. You can DEFINITELY blow up engines with a standalone, even with engine protecting features. I have done it.... Lol

[geargrinder]

Dove I can tell you right now the problem with your engine blowing up is:

YOUR operating conditions vs YOUR lack of information and tuning ability for the ECU.

We can go around and around on this 100x but your just absolutely wrong saying the factory ECU is inherently unsafe and blows up engines is 100% flat wrong.

I just looked it up for you. Knock detection maps seem to start around 0x9130 in the common 'short' tune files. For each cylinder there are 16 values of RPM to set knock threshold. You can change knock threshold up or down. You can change the axes of the RPM buckets, factory axis goes 560/800/1000/1200 then +400 after that. Each cylinder has a unique map from factory based I'm sure on resonances of the block and rotating assembly. Beyond that if I spent enough time w/ WinOLS I'm sure I could also tell you where the ignition-pull values are to increase the amount of ignition pull back.

You could easily pull down some of those thresholds to stop your engine from pushing limits but - since we all know you pretty well at this point - we ALL KNOW that, even if you had done that when you had that car, you'd immediately be whining at us wahh wahhh your motor makes no power because its constantly knocking like a mutherforker.

The problem is your gas, your car, your air temperatures, your lack of sensible operator detection that the motor was being pushed past its limits. Not the ECU.

Oh and only about a zillion big turbo big power cars out there run without EGT. It is decidedly a 'nice to have' but in NO WAY is a requirement.

The problem is your gas, your car, your air temperatures, your lack of sensible operator detection that the motor was being pushed past its limits. Not the ECU. Or its lack of EGT.

[tptrsn]

Dude, CLASSIC POST!! Lol

And regarding EGT, to me interpreting EGT readings is another whole layer of puzzle pieces to be figured out. It is anything but straight forward.

[dovlet]

Dove I can tell you right now the problem with your engine blowing up is:

YOUR operating conditions vs YOUR lack of information and tuning ability for the ECU.

We can go around and around on this 100x but your just absolutely wrong saying the factory ECU is inherently unsafe and blows up engines is 100% flat wrong.

I just looked it up for you. Knock detection maps seem to start around 0x9130 in the common 'short' tune files. For each cylinder there are 16 values of RPM to set knock threshold. You can change knock threshold up or down. You can change the axes of the RPM buckets, factory axis goes 560/800/1000/1200 then +400 after that. Each cylinder has a unique map from factory based I'm sure on resonances of the block and rotating assembly. Beyond that if I spent enough time w/ WinOLS I'm sure I could also tell you where the ignition-pull values are to increase the amount of ignition pull back.

You could easily pull down some of those thresholds to stop your engine from pushing limits but - since we all know you pretty well at this point - we ALL KNOW that, even if you had done that when you had that car, you'd immediately be whining at us wahh wahhh your motor makes no power because its constantly knocking like a mutherforker.

The problem is your gas, your car, your air temperatures, your lack of sensible operator detection that the motor was being pushed past its limits. Not the ECU.

Oh and only about a zillion big turbo big power cars out there run without EGT. It is decidedly a 'nice to have' but in NO WAY is a requirement.

The problem is your gas, your car, your air temperatures, your lack of sensible operator detection that the motor was being pushed past its limits. Not the ECU. Or its lack of EGT.

Bro, read one more time my wordings, I said stock ECU is not for Forcing induction. It has knock mapping, everybody knows it, but the question is whether it is wor or no. It does not properly and that is fact. In my case, all my engines destroyed in combustion chambers due to knocking & heats. If stock ECU works well as you beautifully described above, then we will never get a problem and nobody switched to aftermarket ECU. No one will compromise safety, me too, but my stock ECU does. Knocking is the worst thing which can happen with ECU, it destroys everything and increasing heat in the chamber. ECU can compromise some safety things but not a knocking. For me, that means stock ECU is the worst thing ever I have seen. Noone can change my mind even you BRO.