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BMW 3-Series (E90 E92) Forum
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another high boost N54 engine failure
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10-07-2010, 01:14 PM | #221 | |
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Look for a detailed explanation of "detonation" -- beware its not just simply knocking/pinging in the engine. when you have a grip on how detonation affects cylinder pressures (or rather disrupts), you will see why its not an engine hp output problem -- managing detonation is every engine builder/tuners concern when putting together a forced induction engine package. btw: enrita is basically correct -- a rework of the engine is required if damage of this magnitude has been sustained speculation can prevail here, but basic engine technology MUST be understood to make a educated analysis. -- |
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10-07-2010, 03:08 PM | #222 | |
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10-07-2010, 03:29 PM | #223 |
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But do the codes really matter or mean anything at this point?
I thought it was posted that it was a cold start, and it just went kaputz? So whatever damage was done, happened over a period of time previous to that cold start likely. We need the engine torn down, gone over and investigated/documented what exactly is wrong. Which ever way it gets repaired, I see upwards of a 10K repair bill.
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10-07-2010, 04:52 PM | #224 |
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Damn that sucks for the OP..
But come on really Calvin and Shiv.. We have seen 2 failures from JB3 owners, who have been pushing 19+ psi and you use this to take a dump all over your competition.. Lets say there are only 1000 JB3's running around out there.. That's a .002% failure rate... I mean your record isn't squeaky clean either. |
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10-07-2010, 04:56 PM | #225 | |
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10-07-2010, 05:06 PM | #226 | |
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And just because there have only been 2 public engine failures in the last couple of months, does not mean that there have not been more behind the scenes. Nor does it mean that there aren't many people out there who have not experienced catastrophic failure but rather the far more likely scenario of excessive engine wear and tear from the additive effects of mild/moderate detonation. The basics of engine tuning theory can't be ignored. It's convenient for the developer of what is essentially a boost controller to say that this DME is "different" and that you don't have to tune it correctly. But that, quite clearly, is not true. And I think that everyone, deep down inside, knows that. |
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10-07-2010, 05:14 PM | #227 |
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Hey, I'll just play it safe. Don't run a JB3 and don't run a CMGS. I'm not saying its JB3/CM's fault, but hey. If you're getting on a flight and one of the pilots has crashed before, which plane are you getting in regardless of what the reasons were? You'll take the one with the overall better track record.
EDIT: There is no, 'But but but!' when you deal with this stuff. I've seen two failures with the JB3 and have heard of one with the procede. I strongly feel that it will become even more distinct as things progress. If the JB3 didnt' aquire these so called useless progressive features of the procede then it certainly would. You can argue who came out with it first but thats not what I'm saying. I'm saying, as it stands without those features one tune is less cautious and have been adamant saying that its not necessary to be SAFE! Now here they go saying taper it back because its not safe... Well then as soon as they get these 'progressive' 'autotuning' features I promise you they'll tell you its so great you can ramp it back up to 18-19psi. Suddenly its not cmgs or the engine's fault now is it? PERSONALLY I feel that if all tunes were equal, I'd statistically be a tard to try the jb3. Again, thats only my opinion. Bash me if you want but its simply my outlook on this. I'm not forcing anyone to think the same way as me so really there is no reason to reply. Last edited by klipseracer; 10-07-2010 at 05:22 PM.. |
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10-07-2010, 05:18 PM | #228 | |
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maybe not the best analogy. |
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10-07-2010, 05:21 PM | #229 |
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well.. i think that's a bit extreme. But the point is that people need to be realistic with what each tune can do and do SAFELY.
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10-07-2010, 05:33 PM | #230 | |
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Maybe I can explain it in more lamens terms so people understand using ARBITRARY numbers. Common rules of tuning 1) As boost increases, GENERALLY, you will decrease ignition. 2) As boost increases, Fuel needs will increase 3) Depending on Engine Load and RPM, Ignition "maps" and "fuel maps" determine STARTING Points for fuel and ignition. So arbitrarily a car with 8-10 PSI, wants 15 degree ignition at 5000 RPM. Now, in fairytale world if you want 20 psi at 5000 RPM, you would generally reduce ignition maybe to 10 degree ignition for a starting point. Where SOME TUNES (not naming tunes) they rely on the STOCK MAPS (of ignition) in this case as a starting point which are too high for starting points. Luckily our car unlike others adapts rather quickly. What happens is everytime you go out, the car assumes 20 degrees ignition is good at 5000 RPM. The beauty behind this car is it adapts, and very quickly which is not traditional in your basic car. (Most cars run extremely conservative ignition and rich fuel and dont adjust or barely adjust (especially at WOT). AKA open loop at WOT. Now im getting beyond the scope of things.) Back on topic... So now you are running 20 PSI but your "starting" ignition is at 15 degrees whereas if you "tuned" your maps accordingly (follow the basic rules) you would make your starting point say 10 degrees. So the car is constantly adapting and riding the knock sensor. Literally its saying "Whoa 15 degrees ignition was too much, lets lower it" and it does this at a rate im not sure, but it does it often nonetheless. Viewing the screen image of a car I tuned in the past... If you look at the top Left (redish graph)... you will see as you move to the right (increase load/boost), Ignition is reduced. These are the so called starting points of ignition I speak of. In this vehicles case, the stock ecu can only adapt the first 6 columns (IIRC) to reduce ignition as needed, after that you are left with the choice of the tuner as to if that ignition is good enough thereafter. This specific vehicle will not adapt ignition like our trusty BMW Ecu. However, point being, and this is ONLY A THEORY and NOT CALLING OUT ANY TUNES, with heavy abuse, its very possible that sitting on these high ignition values as starting points, and having the ECU constantly adjust ignition values up and down, it may be abusive long term.... MAY <--- Keyword. I hope this post simply teaches people how ignition works, and nothing more. PS. if your a viewing the large horizontal graph on the right, your "boost columns ignition" would be towards the bottom. As you can see, they are "smooth as silk". The columns above are "stock ignition values" for N/A applications. Those were not tuned in this image. |
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10-07-2010, 05:34 PM | #231 | |
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10-07-2010, 05:42 PM | #232 | |
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CORRECTION". If one were to connect a meth kit to your tuning and not enable a failsafe system it would "autotune" itself to a similar condition of high boost and full advance. And if the meth took longer to spool up or stopped during a run one would expect similar results. One need only look at a pump gas PROcede datalog showing the huge knock/timing drops at 4000rpm to know that all of these systems are riding the factory knock system.... Mike |
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10-07-2010, 05:51 PM | #233 | |
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10-07-2010, 05:56 PM | #234 |
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+100 JPSLICK
You and me have been preaching this for months now. However the jb crowd seems to believe in the hotrod style of tuning. Shove a meth line through the interior, run it through your cheeks, if it vibrates your ass while floored, the car is gonna run 11s. |
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10-07-2010, 06:09 PM | #235 | |
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Mike |
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10-07-2010, 06:14 PM | #236 | |
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That made my day...
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10-07-2010, 06:16 PM | #237 | |
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As for hidden timing corrections, go ahead and scope it and see for yourself. For months, we've been amused that you (Terry) haven't noticed this during your reverse engineering sessions. |
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10-07-2010, 06:17 PM | #239 | |
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10-07-2010, 06:38 PM | #241 | |
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10-07-2010, 06:44 PM | #242 | |
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And this thread has nothing at all to do with knock threshold system anyway because as evidenced by your own and JPs logs the V4 runs 0% CPS on meth. No different than the JB3. Mike |
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