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    Post Discussion: Is the DME a "safe" Failsafe?

    http://www.e90post.com/forums/showthread.php?t=716532

    Click here to enlarge Originally Posted by Thomas@GIAC Click here to enlarge
    The DME acts as a built in fail-safe when you allow it to function properly. If meth flow lessens or comes to a halt, the DME will be able to pull the necessary timing. If you run out of meth, I would recommend switching back to the pump file using the handheld switcher. While the Race file can pull enough timing to run on regular octane, it is easy enough to simply switch back to the pump file.
    So how do you guys feel about this statement? I honestly lol'd first, then C&P into my signature. But it got me thinking... Can one really trust the DME to always react quick enough to prevent any damage? My gut says no, but with all the tuned N54's and no reports (that ive seen) of a detonation related engine failure, can we say that the DME can really act as a failsafe at FBO/Meth power levels?

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    I think all the happy JB guys are a testament to that statement.
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    http://www.e90post.com/forums/showthread.php?t=716532

    So how do you guys feel about this statement? I honestly lol'd first, then C&P into my signature. But it got me thinking... Can one really trust the DME to always react quick enough to prevent any damage? My gut says no, but with all the tuned N54's and no reports (that ive seen) of a detonation related engine failure, can we say that the DME can really act as a failsafe at FBO/Meth power levels?
    That's a great question, hard to answer actually as it can be argued both ways. I also go back and forth on it all the time. Gut feel always, blindly and without thinking, tells me to always have a failsafe outside the DME that will monitor flow for overflow, underflow, low tank level and proactively do something about it. Just gives that warm feeling to the setup that it has that extra in there for just in case.

    Now having said that, on my own car, I've had my old Coolingmist kit fail on me more than once. And that was on full boost, pump 94 octane, and timing close to stock, while testing. Nothing ever happened even on back to back pulls on one occassion. I dynoed 472whp once with RBs only to realize it was on pump gas only as my meth flow wasn't there due to a melted boost line! No failsafe back then with that kit, DME pulled out A LOT of timing, boost was still high, AFRs were rich though in the mid to low 11s. With that same kit earlier I was at the drag strip doing runs. Everything was fine for the first couple pulls, reviewing logs after each run, running around mid 125-126mph traps. Then on one run I ended up run ~125mph, checked the log thinking its the usual and to my surprise, meth flow wasn't there for the entire course of the run, DME again pulled timing out heavily, boost was high as well as IATs and I had pump 94 in the car again.

    Now taking these real life situations one can classify them as being lucky and getting away with it. However, I think from another point of view one could argue that the DME really "can" act fast enough to pull out timing in the case meth flow fails.

    In any case, in my world, I'd recommend having some sort of a failsafe, or at a minimum, a flow gauge, then dealing with any possible consequences.
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    I would say so... years of piggyback usage have proved this. Sure, the flash way is the prefered pro active way but this ECU has proven time and time again to be great in that respect.

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    It's much more dangerous than just running 18psi with no meth on the OEM advance curve (which isn't a good idea) because without meth the DME will simply hold advance very low / make lots of 3 degree corrections. Once you add meth the DME learns up advance to it's ceiling, and then if the meth stops flowing mid run you wind up with knock faster than the DME is programmed to respond. It's very good at making relatively small timing corrections over time and learning a curve for a given boost and octane level. It's not so good at sudden huge corrections that come from a meth failure.

    My advice to anyone running meth would be to run an integrated system like the JB4, or if you're going to use a flash without a safety just keep advance low enough to mitigate much of the risk. On my to-do list is to write a Cobb meth failsafe system for you flash guys. It should be as simple as having the safety trigger an implausible IAT condition that results in massive timing pull on the DME side.
    Last edited by Terry@BMS; 07-13-2012 at 12:42 PM.
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    http://www.e90post.com/forums/showthread.php?t=716532



    So how do you guys feel about this statement? I honestly lol'd first, then C&P into my signature. But it got me thinking... Can one really trust the DME to always react quick enough to prevent any damage? My gut says no, but with all the tuned N54's and no reports (that ive seen) of a detonation related engine failure, can we say that the DME can really act as a failsafe at FBO/Meth power levels?
    you need to run the octane for the power your wanting to achieve, this is basics.

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    The difference between DME corrections and piggy reducing tuning is correction in all 6 cyl compared to maybe correction in 1 cyl, but likely none. With the DME it's only timing, but you'll still be on full boost. Mechanical failsafe is better than nothing, but still not ideal due to the time delay. Even an IAT correction is not very good. The sensor will have some liquid on it for a little bit and temp will increase slowly... not to mention there seems to be a slight delay in IAT signal anyway.

    Best tuning is a stacked combo

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    @JoshBoody, the DME can react by reducing load target as well, you can modify these settings using ATR. I'm not so much interested in comparing Piggy VS Flash tune, but rather discussing the DME itself. It seems like we have been spoiled with allowing the DME to step in when needed, and some tuners appear to have no problem leaning on this theory pretty hard - GIAC for example. Its a pretty bold claim to say that you can just use the DME as a failsafe. I wish someone had the capacity to do some lab testing of a DME/N54 at varying power levels to see how effective it is at preventing its own demise.

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    Good discussion. TBH, one of the reasons I chose to get the GIAC tune was the ability of the DME/flash to intercept any potential catastrophe before it actually happens. I was advised by Austin @ GIAC, that the piggy can do the same thing but with additional fail-safe systems, albeit it may take bit longer to relay the info to the DME. I have the CM meth kit and while I turned my fail-safe system off, I'm assured that the DME is doing its job by triggering the knock sensor and retarding timing all without issues.

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    I will say that the fuse to my meth kit blew before (several times before the issue was corrected in fact), and in one instance I was running Map 9 on the JB3 w/ only 93 octane. I didn't realize meth stopped flowing until the car went into limp mode and threw a CEL. The DME detected excessive knock and reacted. Probably saved the engine.

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    GIAC is desperately trying to retain any presence in BMW marketshare. Unfortunately, with the latest beta maps from Cobb, their game is almost completely gone.

    Some of you may know that I've been preaching the excellent driveability and predictability from the GIAC tune for more than two years now. But now, they've been equalized in this department by Cobb.
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    Click here to enlarge Originally Posted by vasillalov Click here to enlarge
    GIAC is desperately trying to retain any presence in BMW marketshare. Unfortunately, with the latest beta maps from Cobb, their game is almost completely gone.

    Some of you may know that I've been preaching the excellent driveability and predictability from the GIAC tune for more than two years now. But now, they've been equalized in this department by Cobb.
    Hey Vasil, so have you tested the new maps on track yet to see whether you still get that overboost limp?

    but yeah, the new maps are a great improvement over the previous beta maps
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    Tomorrow! Click here to enlarge I am heading to BlackHawk Farms raceway. That'll be a good test for those maps.
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    @ Vas I think you're right, BUT the fact is that GIAC is the pioneer in getting a tune this powerful while keeping stock like drive-ability. On the other hand, the lack of steady representation on the forums and release of newer maps makes it a bit difficult to keep up to other ones. Having said this, I hope that I can get my hands on the beta tune rather soon to give everyone an update on how this new file performs.

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    Click here to enlarge Originally Posted by orange Click here to enlarge
    @ Vas I think you're right, BUT the fact is that GIAC is the pioneer in getting a tune this powerful while keeping stock like drive-ability. On the other hand, the lack of steady representation on the forums and release of newer maps makes it a bit difficult to keep up to other ones. Having said this, I hope that I can get my hands on the beta tune rather soon to give everyone an update on how this new file performs.

    Oooh, I agree completely. I've been praising GIAC for a long time and I've always pointed out the weak spots in Cobb's tune. What really kills GIAC is the delivery method of the tune. You have to go see a dealer. You have to make an appointment. You have to pay labor. You have to constantly deal with the dealers when there are map updates or if BMW releases a new firmware. Its a major pain in the ass. On the positive side of things: check out GIAC's mobile app. It is very useful and it gives you some excellent functionality.

    I know I probably sound like a broken record by this point, but I think all of the time I've spent waiting on Cobb to finally evolve their tune to a respectable level is finally paying off. And with ATR already out, things can only get better.

    Anyway, to get things back on topic: My personal opinion is that nothing should be left out to chance. If GIAC considers the N54 ECU smart and fast enough to pull timing and prevent the engine from damage (if meth fails), then I want to see theoretical reasoning behind those claims. ...and no, current BMS and Proceed users do not count as proof in my book because up to this point few of them have been pushing such high boost and such high ignition advance in conjunction with meth. ..and the N54 engine is very forgiving with its forged internals. So none of the tuners should be sitting on their laurels and not tune the engine correctly.
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    It's much more dangerous than just running 18psi with no meth on the OEM advance curve (which isn't a good idea) because without meth the DME will simply hold advance very low / make lots of 3 degree corrections. Once you add meth the DME learns up advance to it's ceiling, and then if the meth stops flowing mid run you wind up with knock faster than the DME is programmed to respond. It's very good at making relatively small timing corrections over time and learning a curve for a given boost and octane level. It's not so good at sudden huge corrections that come from a meth failure.

    My advice to anyone running meth would be to run an integrated system like the JB4, or if you're going to use a flash without a safety just keep advance low enough to mitigate much of the risk. On my to-do list is to write a Cobb meth failsafe system for you flash guys. It should be as simple as having the safety trigger an implausible IAT condition that results in massive timing pull on the DME side.
    great thats exactly what i need Click here to enlarge
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    1 out of 1 members liked this post. Yes Reputation No
    A couple of us responded over on E90post to GIAC by posting datalogs of failsafes working proactively by dumping boost when meth flow stops.

    It's not even a discussion that having a proactive failsafe is a good idea.

    The DME still functions reactively if it needs to.......but GIAC kept infering that having to use a failsafe was an indication of an "inferior" tune and that it's best to let the DME manage engine knock scenarios.

    OK

    No argument that the DME will pull timing when it has to. But what I can't tolerate about their position is that somehow they keep infering that the piggies don't allow this to happen because they are intercepting signals and fooling the DME.

    While that is true in terms of CPS offsets and boost levels.....it is not true about knock. Piggies do not intercept or alter knock control and that failsafe is still very functional......even with a proactive failsafe like meth flow monitoring.

    I lost all respect for GIAC on that debate. It was all a marketing exercise as far as I am concerned.

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    @Dcafs, I agree.

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    Click here to enlarge Originally Posted by vasillalov Click here to enlarge
    and the N54 engine is very forgiving with its forged internals.
    invalid statement

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    Click here to enlarge Originally Posted by DCAFS Click here to enlarge
    A couple of us responded over on E90post to GIAC by posting datalogs of failsafes working proactively by dumping boost when meth flow stops.

    It's not even a discussion that having a proactive failsafe is a good idea.

    The DME still functions reactively if it needs to.......but GIAC kept infering that having to use a failsafe was an indication of an "inferior" tune and that it's best to let the DME manage engine knock scenarios.

    OK

    No argument that the DME will pull timing when it has to. But what I can't tolerate about their position is that somehow they keep infering that the piggies don't allow this to happen because they are intercepting signals and fooling the DME.

    While that is true in terms of CPS offsets and boost levels.....it is not true about knock. Piggies do not intercept or alter knock control and that failsafe is still very functional......even with a proactive failsafe like meth flow monitoring.

    I lost all respect for GIAC on that debate. It was all a marketing exercise as far as I am concerned.
    Can you attach a link to where this was stated by GIAC. What I read was this: "The DME acts as a built in fail-safe when you allow it to function properly. If meth flow lessens or comes to a halt, the DME will be able to pull the necessary timing".

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    Click here to enlarge Originally Posted by orange Click here to enlarge
    Can you attach a link to where this was stated by GIAC. What I read was this: "The DME acts as a built in fail-safe when you allow it to function properly. If meth flow lessens or comes to a halt, the DME will be able to pull the necessary timing".
    http://www.e90post.com/forums/showpo...1&postcount=31

    From GIAC: "The idea that meth is safer with a piggy-back is not true. The fact remains that these systems cannot control timing, which is why they must have "safeguards" in place and run on separate maps. With the speed at which the new DME's process, I can assure you that you are much safer letting the DME make adjustments than an external system.

    By recalibrating the entire DME, we allow it to work seamlessly with the engine. On our Race file, it can quickly detect any problem with fueling and make an adjustment within a couple revolutions. An external DME has water-methanol safeguards in place because it has to. When you allow the DME to function properly, without intercepting signals, it acts as its own safeguard."

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    So much for shopping the competition lol, so much confusion over how the piggys operate.

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    Click here to enlarge Originally Posted by DCAFS Click here to enlarge
    http://www.e90post.com/forums/showpo...1&postcount=31

    From GIAC: "The idea that meth is safer with a piggy-back is not true. The fact remains that these systems cannot control timing, which is why they must have "safeguards" in place and run on separate maps. With the speed at which the new DME's process, I can assure you that you are much safer letting the DME make adjustments than an external system.

    By recalibrating the entire DME, we allow it to work seamlessly with the engine. On our Race file, it can quickly detect any problem with fueling and make an adjustment within a couple revolutions. An external DME has water-methanol safeguards in place because it has to. When you allow the DME to function properly, without intercepting signals, it acts as its own safeguard."
    Depending how you look at it the above may or may not make sense

    One way to slice it is the following: IF the DME were to use requested/actual MAF (i.e. boost oversimplified) values in calculating its TOTAL amount of ignition correction to be applied then:
    1) it can protect itself due to bad octane (no meth) in a reactive way (not ideal)
    2) running a piggyback to up boost when on meth can potentially take away from that safety as true MAF values won't be seen by the DME as its being told its running stock load targets (stock boost) and in turn the DME won't be able to calculate the required total timing correction.

    The other way to slice it is if MAF values don't play into the timing correction calculation equation at all. It uses knock sensor voltage (which are available as loggable channels) and the current ignition timing and corrects using a 1-D timing correction table somewhere that's setup to say have a horizontal axis being knock voltage and values being a factor representing correction to be applied. In this case, running a piggyback on top would not take away from the DME's built-in safety mechanisms.

    The one question really is, are the external failsafes really that: "failsafes", or, is it the case that all this time the DME was the saviour and the "failsafes" we've been using grew on us as methods of failsafing. Does the DME really truly need an external failsafe? Where is proof of this, or, where is the proof that it doesn't need an external failsafe?

    In any case, what I'd personally love to know more about is the logic/handling that the DME uses when it comes to issuing timing corrections. For instance, how does it know to correct 2.x vs. 3.x vs. 10.x degrees and what does it base the calculation on. Obviously, it is responding to events happening in the engine's dynamic running environment but more insight into what is actually involved would be great to know.

    In terms of failsafes, I'll continue to run my built-in failsafe that comes with the HFS-4 kit. I'll also recommend anyone else running meth to also run any failsafe on top of the DME as it'd be pretty foolish to recommend otherwise due to the current lack of knowledge into the DME's timing correction calculations/handling.

    If we'd like to take this thread further on this topic let's try to discuss the two of the following:

    1) How could we quantitatively prove the DME being or not being able to cope on its own with a loss of meth flow.

    2) How could we quantitatively prove the external failsafe being fast enough to react and save the motor in case of bleeding edge, ballztothewall, no compromise/cushioning, aggressive tune made for pump gas and meth. (To my knowledge, a few engines that have had external failsafes, still had documented internal failures. Flow sensors were in, wired up, did they work or not or whatever, that's outside the scope of this discussion)

    Fire away..
    Last edited by dzenno@PTF; 07-15-2012 at 01:26 PM.
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    Click here to enlarge Originally Posted by DCAFS Click here to enlarge
    http://www.e90post.com/forums/showpo...1&postcount=31

    From GIAC: "The idea that meth is safer with a piggy-back is not true. The fact remains that these systems cannot control timing, which is why they must have "safeguards" in place and run on separate maps. With the speed at which the new DME's process, I can assure you that you are much safer letting the DME make adjustments than an external system.

    By recalibrating the entire DME, we allow it to work seamlessly with the engine. On our Race file, it can quickly detect any problem with fueling and make an adjustment within a couple revolutions. An external DME has water-methanol safeguards in place because it has to. When you allow the DME to function properly, without intercepting signals, it acts as its own safeguard."
    I'm not so sure it's a marketing ploy on Giac's part. I mean this really isn't their selling feature. However, I agree with Thomas' statement that the DME would be the fastest product able to make parameter adjustments. I think we all agree on that. Logic would dictate that a native brain would be much more efficient in relaying data than an external one. Call me crazy. That being said, I would love to know what tweaks GIAC has made to each of their files in an effort to hasten timing control. I would have to agree with Dzenno's statement and say that you can never be too safe. Adding an extra layer of protection is definitely worth the small expense!

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    Dzennos approach is a fair one.....there is too much unknown about what GIAC is doing to promote their claim, so one can only assume they are letting the DME correct tming via knock sensors or some calculated value that monitors meth flow somehow.

    In either case.....it's a reactive mechanism. The meth failure has to happen first and symptoms have to be noticed by the sensors at a combustion chamber level (ie knock or fuel trims or AF ratios).

    An external failsafe monitors only one thing = meth flow. It doesn't even talk to the DME. It gives the green light to the piggy to go ahead an increase boost once methflow is confirmed. Conversely, if it notices methflow has dropped, it signals the piggy to drop boost to stock levels.

    This is proactive approach based on adequate methflow.

    I can't prove that it's quick enough to avoid knock events other than my own datalogs where meth flow stopped unexpectedly and boost dumped down to 9 psi very suddenly. I had no knock occurrences on those logs, so it seems to work as claimed.

    Why wait for the knock to happen once methflow gets messed up?

    I think Dzenno has stated that in his own examles he didn't realize meth wasn't flowing and saw that huge amounts of timing had been pulled by the DME. It didn't grenade the engine, so I guess you can conclude that the DME did a good enough job of dealing with the situation.

    But still, I don't know about you - but I strive for as little knock activity as possible. So for me, an external failsafe achieves this, even if a so-called falisafe isn't really needed when the DME will pull timing anyways.

    Besides......this isn't really a discussion about piggybacks if you think about it.....it's really about external failsafes. The fact that GIAC blends the two together just serves their ability to discredit the competition.

    Actually I would bet that even Cobb probably runs an external device with their own car using the HSF4 kit.

    Anyone know?

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