cj.surr

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.

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.

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? 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.

I have the same problem with my S52 discussed in this thread: My issue was voltage dropping too low during starting. One thing that may help is powering the ecu and engine electronics directly from the battery instead of the starter terminal. That way it is not subject to the voltage drop of the starter power cable during cranking.

OK, so to recap this thread, and please correct me if I'm wrong... Due to lack of response on the actual substance of my original post, I am assuming: A- Link is not disclosing a reason for disabling boost cut during shift cut and torque reintroduction. B- Link will not be changing boost cut to take priority over all other cuts

I already know multiple ways to keep this from happening again. I could make an aux input that activates a low GP rev limit if MAP is above a certain value. My point is that the integrated MAP limit feature is NOT comprehensive, as seen by my experience. I was just hoping for Link to change the MAP limit to actually protect the motor in all scenarios. This way I can continue using the feature and this will not happen to someone else. It is not fair to assume that the tuner would know that MAP limit doesn't work during shift cut or torque reintroduction. The programming oversight cost me thousands of dollars and lots of my time, as well as making me look bad by oiling down the whole track. As well as ending my season. It's not like I'm asking anyone to build me another motor, but a "sorry" would have been in line, in my opinion.

Another super tuner looking to shit on my tune for their own ego, awesome. I had a hard limit boost cut at 290kpa and was targeting 270kpa. Why should I anticipate a need to have my timing settings dialed in at 320kpa, a level I didn't want to be at, and shouldn't have been able to get to? Also wall wetting and secondary injection is a thing, not everybody wants the occasional lean firing that comes with a fuel cut. There is no inherent danger to the engine from an ignition cut.

Clearly, but why? My experience should be a clear example of a reason why boost cut should take a higher priority. As the tuner, this seems like an unreasonable thing to have to assume. Common sense says that the cut that is calling for the highest % cut should take priority. I'd rather not do a fuel cut because I have secondary methanol injection and it's slower than ignition cut.

Still hoping to hear from Link on this one... I am feeling left out to dry.

Thanks for taking the time to look into this and pass it along. I don't know anything yet about the failure except that part of the rod exited the oil pan. I was also surprised how close I was to the edge, but the car runs 93 octane (AKI) and direct port water meth. So it's not going to be as knock resistant as E85 or race gas like most people run at these kinds of boost levels. In addition, my timing in that 320kpa cell was fairly aggressive considering that I have never attempted to dyno tune it at that level and never expected the ECU to see that cell. It is only about 1 deg less than at 280 kpa. I can be pretty sure that the failure was due to preignition (my best guess) or extreme knock. I will also be testing my injectors and water nozzles to see if that played a factor. However, I don't think it's a coincidence that a motor that has been seemingly perfectly healthy at 270-280 kpa for over two years would completely fail the first time it saw 320 kpa. It was a very short period of time but I think it's completely possible to destroy a rod in 5-10 cycles.

Yes, exactly. This is the problem with the code. Why wouldn't this be possible? I have already explained how this can be dangerous. MAP Limit should always be able to 100% cut ignition if boost is above the hard limit. It shouldn't matter if the engine is in RPM Limit, shift cut, whatever. If there are ignition events occuring, MAP should not be above the limit, period.

When I look at the log, I see MAP limit being activated at 22.18s. At 22.03s, my MAP is over the limit at 303kpa and rising. The hard limit is set to 100% igntion cut and the hard limit delta is set at 3kpa. MAP limit at this point is somewhere between 290 and 300kpa. 100% ignition cut did NOT engage and MAP limit did not pull timing. The timing being pulled is from the torque reintroduction. MAP limit 100% cut only takes place after torque reintroduction is complete. The MAP limit status is not logged at a fast enough rate to get an exact idea of when it was actually flagged as active, but you can tell the ignition cut is not where it should be. I don't understand why you're being argumentative. I completely understand that the RPM limit settings were too aggressive. Your suggestion about the DC% table is honestly ridiculous because the engine should have a 100% ignition cut INSTANTLY if it ever passes the MAP limit + 3 kpa. The ECU should never need to be pulling a DC% from there. The wastegate would not act fast enough to save the engine anyway. And you can completely forget about that helping in a wastegate failure scenario.... It's a hack and incomplete way to prevent an overboost. It's clear that the hard limit on boost cut did not come in when it should have because it was during a shift cut (partial cut). What I want is an answer from the developers why it was programmed this way and if this can be changed.

I'm very aware of what happened. I feel like you didn't read my first post. My question is: why doesn't MAP limit engage during rev limit or shift cut or torque introduction? All of these can be progressive cuts, meaning some cylinders are still being fired at full load and over the MAP limit. It seems like an oversight to me. I'd really like to see it changed.

I don't remember the boost pressure rising when setting up the RPM limit. That being said, I didn't set it up 8 seconds into a drag run, so obviously the manifold would be much colder and much less prone to boost level rise. I'm not saying my RPM limit and shift cut settings are perfect, I can see that they need some changes. AFR target is 12.0 and it's in low 11s... Not sure what your point is there. I am the tuner and I don't expect MAP limit to control boost. That's why I have the hard limit set at 3kpa and basically no control range. I have a slow ign % return on igntion cut. If it overboosts, I get 100% ignition cut and a couple seconds to lift off the pedal. That's how I want it and how I have tested it successfully. My turbo is far too high strung to try to use fuel or ignition cut to control it. I see what you're saying about lowering the DC but it should have never been in that boost area. Boost cut should have engaged at 293kpa. Instead it let me get to over 315kpa at full load. You can try to bash the tune all you want, but at the end of the day, MAP limit didn't work when it should have and that's what allowed the motor to blow. The car was still in progress of being tuned, I was counting on MAP limit to save the motor if it came to that.