Map Limit didn't engage during Shift Cut

[cj.surr]

1 hour ago, Stevieturbo said:

Perhaps get back into the real world and use some common sense.

Why should you need to anticipate basic tuning for cells ? Seriously, think about what you're saying.

 

And BS about the "lean firing that comes with fuel cut" 

Do you understand how the boost cut hard limit works? It 100% cuts ignition immediately at the setting (290 kpa). There is no reason that my timing cells at 320 kpa should need to be dyno tuned. It's not like I had 30 deg in that cell or something crazy. I didn't want the engine to ever see that cell and it shouldn't have. The only reason it saw those cells was because boost cut was DISABLED. Which is the point of this thread. 

43 minutes ago, Ducie54 said:

Glad I'm not the only one thinking the same thing. 20 times the statistics show it has hit MAP limit, you would of hoped the tuner worked it out before it blew. 

Trying so so hard not to pick this to threads.      

You spent like 5 posts arguing that boost cut was working, until Adam and Simon confirmed that it was actually disabled (like I said). I didn't ask for your help and I clearly don't need it. Can you please sit down?

 

Seriously, I don't want any more discussion of what you two think of my tune. This is about MAP limit not working during shift features. I'm not interested in hearing about your work-arounds. I'm not interested in how I need to prepare if my ECUs safety function doesn't work as it should. I just want MAP limit to work in ALL SCENARIOS like any tuner would expect.

 

[Ducie54]

Again please reread, rpm and map limit don't work together as shown by my example. As I said and again by LINK. Your poor rpm limit caused the MAP to increase. Again shown by the log.

What ECU brand has MAP limit working with shift active? I'm a tuner and would rather shift cut before map limit. Miss shift can't be undone, a shitty tune can. 

[cj.surr]

29 minutes ago, Ducie54 said:

Again please reread, rpm and map limit don't work together as shown by my example. As I said and again by LINK. Your poor rpm limit caused the MAP to increase. Again shown by the log.

What ECU brand has MAP limit working with shift active? I'm a tuner and would rather shift cut before map limit. Miss shift can't be undone, a shitty tune can. 

I don't know what other ecus do in this situation, it's obviously not a common occurrence. 

 

Think about your statement. You would rather the engine overboost than have a mis-shift? Forget the cause of the overboost, It could be caused by software or hardware.

[Ducie54]

5 hours ago, cj.surr said:

Think about your statement. You would rather the engine overboost than have a mis-shift? Forget the cause of the overboost, It could be caused by software or hardware.

There is a reason LINK has a shift cut prioritized over other cuts. As others have mentioned a tunner should build into his map a safe guard to reduce boost, ignition and increase fuel in the area of the MAP were damage could occur if reached.

IMO a MAP cut should only be reached if the wastegate line falls off.

Stop being so defensive and take advice, no one wants to hear about members spending money or time on things that can be fixed. There's a handful of software changes I love to happen, but know it never will and I just have to learn to work around that. 

I'm sure if you asked several guys would be happy to help if your not interested so be it.

While I'm far from a pro tuner I still know the basics and spend a fair amount of my free time helping members fixed there payed tunes. I got better things to do than troll on fourms, getting too old for that Shit.

[Adamw]

Please keep it civil guys, I believe cj.surr's concerns are valid, especially when some of the complexities he has stumbled upon are not well documented. 

cj.surr, I believe the reason it is done the way it is with gear cut taking priority is because with a progressive randomised cut strategy you can only have one limiter active at a time.  The sequencing of the randomisation of the cut pattern has to be scheduled several cycles in advance and is hugely complex so you cant just tell it to to monitor all possible limit conditions and pick whichever one needs the highest % cut.  Gear cut needs almost the highest priority as in some forms of racing where there are boost or RPM restrictions many competitors run nearly the whole race just touching the first few percent of these limits - since gear cut usually requires a much higher cut level (typically 90%), it has to be able to interrupt the active MAP or RPM limits to work properly in these conditions.  I believe most ECUs that have a progressive randomised cut strategy has this same limitation and has to prioritise the different limiters with some type of hierarchy.

In the latest 5.6.7 firmware there were a couple of extra safety over-rides added (one is the fuel hard cut Simon mentioned), that are constantly monitored and take priority over everything else.  Im not sure if there is a reason why an ignition hard limit couldnt also be added to this list of high priority over-rides but there may be processing limitations or something else I dont know of - it is something that Simon will have to discuss with engineering.  Be aware though, it is no quick fix, the limiter strategies are hugely complex and deeply interwoven all throughout the firmware code so the engineers are very cautious when it comes to changing any of it as there is a high risk of creating new bugs - and as you have found it is very difficult to test the interaction of every combination of limiters and all events around them.    

 

I personally still have my doubts that over boost would cause a rod to fail unless the torque bent it enough that the piston seized but I have never seen that happen with an aftermarket rod (certainly can happen with some poorly designed and low yield strength OEM rods).  Compressive loads on a conrod are typically less than half the tensile load, so they nearly always fail in tension.  The boost pressure doesnot effect the tensile load.  As I said earlier I would be interested in seeing photos of some of the failed parts when you have it pulled down - not to say "I told you so", more for my general interest and to get you some closure.  BTW, I am a materials scientist by trade and have worked 25 odd years as a metallurgist - so with my interest in automotive engineering I have a fair bit of experience with engine component failure analysis under my belt.

[cj.surr]

7 hours ago, Adamw said:

Please keep it civil guys, I believe cj.surr's concerns are valid, especially when some of the complexities he has stumbled upon are not well documented. 

cj.surr, I believe the reason it is done the way it is with gear cut taking priority is because with a progressive randomised cut strategy you can only have one limiter active at a time.  The sequencing of the randomisation of the cut pattern has to be scheduled several cycles in advance and is hugely complex so you cant just tell it to to monitor all possible limit conditions and pick whichever one needs the highest % cut.  Gear cut needs almost the highest priority as in some forms of racing where there are boost or RPM restrictions many competitors run nearly the whole race just touching the first few percent of these limits - since gear cut usually requires a much higher cut level (typically 90%), it has to be able to interrupt the active MAP or RPM limits to work properly in these conditions.  I believe most ECUs that have a progressive randomised cut strategy has this same limitation and has to prioritise the different limiters with some type of hierarchy.

In the latest 5.6.7 firmware there were a couple of extra safety over-rides added (one is the fuel hard cut Simon mentioned), that are constantly monitored and take priority over everything else.  Im not sure if there is a reason why an ignition hard limit couldnt also be added to this list of high priority over-rides but there may be processing limitations or something else I dont know of - it is something that Simon will have to discuss with engineering.  Be aware though, it is no quick fix, the limiter strategies are hugely complex and deeply interwoven all throughout the firmware code so the engineers are very cautious when it comes to changing any of it as there is a high risk of creating new bugs - and as you have found it is very difficult to test the interaction of every combination of limiters and all events around them.    

 

I personally still have my doubts that over boost would cause a rod to fail unless the torque bent it enough that the piston seized but I have never seen that happen with an aftermarket rod (certainly can happen with some poorly designed and low yield strength OEM rods).  Compressive loads on a conrod are typically less than half the tensile load, so they nearly always fail in tension.  The boost pressure doesnot effect the tensile load.  As I said earlier I would be interested in seeing photos of some of the failed parts when you have it pulled down - not to say "I told you so", more for my general interest and to get you some closure.  BTW, I am a materials scientist by trade and have worked 25 odd years as a metallurgist - so with my interest in automotive engineering I have a fair bit of experience with engine component failure analysis under my belt.

Thank you for the explanation. I understand regarding the progressive randomized cuts taking priority and how that is necessary. I also agree that any hard limit should be top priority, whether it is rpm, map, GP, etc. Also whether it is ignition or fuel should not be a factor, in my opinion. If that cut is asking for 100% cut, then it makes sense that it would have priority. The whole purpose of a hard cut, in my opinion, is a last line of defense for engine protection. Normal operation should not use a hard cut, but this is the absolute limit that we set, a number we do not want to exceeded under any circumstance.

 

Whether or not my engine failure was due to excessive MAP is really not a factor in this discussion. What is important is that MAP was allowed to significantly exceed the specified hard limit. It could have been 350kpa, 400kpa, etc. That being said, I also have a background as a mechanical engineer and have taken ICE courses. I understand that with an octane limited setup, such as high boost on pump gas, preignition is a serious possibility. The limit for preignition can be a very fine window. At 300kpa, absolutely no preignition may occur. However, at 315kpa, there may be several spots of preignition that result in extremely violent pressure spikes. I feel that this could absolutely cause a compressive rod failure, even in just a few cycles. Preignition stresses really cannot be compared to the smooth flame front of ideal combustion. But, as I said, this is just my analysis of possible cause for the engine failure. I will be analyzing everything while the engine is apart. This is not really important to the topic on hand, which is the MAP limit not being completely comprehensive. 

 

[Stevieturbo]

21 hours ago, cj.surr said:

Do you understand how the boost cut hard limit works? It 100% cuts ignition immediately at the setting (290 kpa). There is no reason that my timing cells at 320 kpa should need to be dyno tuned. It's not like I had 30 deg in that cell or something crazy. I didn't want the engine to ever see that cell and it shouldn't have. The only reason it saw those cells was because boost cut was DISABLED. Which is the point of this thread. 

You spent like 5 posts arguing that boost cut was working, until Adam and Simon confirmed that it was actually disabled (like I said). I didn't ask for your help and I clearly don't need it. Can you please sit down?

 

 

Clearly you need to learn to read.

Nowhere did I say those cells needed dyno tuned...but I did say some basic common sense does need applied to such cells.

And nowhere did I state ever whether your boost cut worked or not.

[cj.surr]

On 11/3/2019 at 2:43 PM, Stevieturbo said:

And nowhere did I state ever whether your boost cut worked or not.

                 

On 11/3/2019 at 2:43 PM, Stevieturbo said:

Clearly you need to learn to read.

 

[Simon]

Points to take from this.

Limits are prioritized.

You need to be aware of cells you could enter into should something go wrong.

We will work on documenting the limit priorities so there is a better understanding around how they interact.

We are offering a tool for tuning and we do our absolute best to avoid issues and test the product extensively. However there is so much flexibility in the setup and possible applications that there is just no way that every situation can be tested or even thought of. 

There is a good family of Link tuners and users that will try there best to help, many of are in the business of tuning and are offing help free of charge and even at possible cost to them. Make the most of this and take the advice on.