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Vishnu Technical: Ignition timing control facts
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07-21-2009, 03:57 PM | #199 | |
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07-21-2009, 04:03 PM | #200 |
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07-21-2009, 04:25 PM | #201 |
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Now doesn't the ECU have to adjust the timing, plus everything else when it adjusts the boost for different altitudes? Don't know if that matters.. Im a noob when it comes to this kinda stuff, so easy on the bashing.
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07-21-2009, 04:49 PM | #202 | |
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07-21-2009, 05:15 PM | #203 |
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Oh shit please dont drag the Flat Earth Society into this too....
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07-21-2009, 05:18 PM | #204 | |
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SHIV im not doubting you dude. im not a Fanboy. F*** everyone cuz when my engine blows up neither you nor Terry are gonna care. Its all about me, myself and I. I totally see what your product does. I just wanna see what mikes rebuttal is about. Hell I might be a future customer of yours. My loyalty is to my car and bank account. And im not arguing against the effectiveness of CPS offsetting. I just think that this thread has gotten way off topic with Vishnu-ites bashing on BMS. Like i said im just in here learning as i go along. edit: whats evolution?
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07-21-2009, 05:31 PM | #205 |
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Not much in the way of bashing until Mr.Happy @ n54tuning.com showed up and started throwing hand grenades. Then Vishnu-ites started pulling the pins and throwing them back.
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07-21-2009, 05:33 PM | #206 |
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But majority of people believe in intelligent design.
http://www.harrisinteractive.com/har...ex.asp?PID=581 http://www.wnd.com/news/article.asp?ARTICLE_ID=49153
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07-21-2009, 06:09 PM | #207 | |
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Unfortunatly the majority of people out there are retarded.. Douglas Adams said it best: "people are a problem". |
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07-21-2009, 07:54 PM | #208 | |
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Some ECUs are more sophisticated than others, they have multiple tables that interpolate with each other based on different contingencies and some ECUs are simple. The DME happens to be a sophisticated ECU, but it DOES NOT THINK on its own. It DOES NOT ADAPT. It reacts to data from the sensors. The interceptor (proceed) takes intercepts the data from the sensors and tells the ECU that it is getting a different signal than what it in the ECU map. The ECU says OK and sends a different signal to the sensors. For example, say the ECU has in its timing map a command telling it to fire the spark plug @ 13* BTDC at 7000 rpm at WOT. The ECU gets a signal from the CPS sensor telling it to do just that, BUT the Proceed intercepts that signal and corrects it by -3* (CPS offset/correction). So now the ECU is told to fire the spark @ 10* BTDC @ 7000 rpm at WOT. The ECU thinks that it is following the map, but it is NOT, it is following what is coming from the sensors via the Proceed. That is all there is to it. The ECU does not think, does not adapt and does nothing of what Mike is saying it does. The ECU takes the data in and spits different data out. This, BTW, is NOT direct timing control. Direct timing control is when you flash the map in the ECU and the DME reads the new timing/fuel data. That, and only that is direct control. For your second question, yes it is possible to determine detonation by logging data from the ECU. Each engine has a microphone attached to it. The microphone listens to the engine and sends the sounds to the ECU. The ECU has multiple filter maps that filter the sound and determines what is knock and what is not. If the ECU determines that a certain sound is knock, then it commands the CPS to retard iginition timing. The ECU usually spits out the knock signal through the CAN/OBDII port and you can log it if you have the necessary logging equipment. Once you log it you will not that every time the knock signal goes higher, there is a corresponding timing retard. When I ran an XEDE I was able to log that signal using an additional device on the harness. Everytime the signal increased the timing got pulled. Maybe Shiv can implement something like this on the Proceed. |
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07-21-2009, 08:25 PM | #209 |
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Agreed. CAS offsetting does not even target a specific timing angle.
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07-21-2009, 08:31 PM | #210 | |||
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You do mean the piezoelectric knock sensors (i hope). They are far from a "microphone." Quote:
oy vey, why did I just pull myself into this thread.... |
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07-21-2009, 08:37 PM | #212 |
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Well I finally arrived back after some delays and had a chance to speak to BMS/Terry and lay down a strategy for testing.
Here is an overview of what we decided we would do. First, we'd like to show that the CPS offsetting is generally learned out by the ECU. We plan to do this by creating a repeatable test, like 2000-7000rpm 3rd gear pulls, in similar weather conditions. Then we will perform this test with a well adapted and well tuned CPS offset in place several pulls to develop effective timing averages over many runs. Then we will disable the CPS offsetting, let the ECU adapt, and repeat this same test to create non-CPS averages. These two sets of averages along with the supporting detail will become the basis for analysis. Second, we'd like to show that total timing advance drops don't necessarily equate proportionally to knock. This is a much more advanced concept and we need to give more thoughts to how to perform the testing in a way that will be accepted by all. The V3 system is perfect to perform this testing as CPS can be turned on and off, and the CPS maps are well developed and accepted by all. Also, we don't have any source code to "tamper" with the device. The first order of business is to recreate the tests in the first post. As you can see by the attached BT log we're having a hard time doing that... So the work continues. Mike P.S Shiv, let me know if its cool to post data in this thread or do you prefer for me to start a new thread. Let me know. . |
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07-21-2009, 08:37 PM | #213 | |
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http://www.burgertuning.com/images/jb3_max_power.jpg |
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07-21-2009, 09:13 PM | #214 | |
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07-21-2009, 09:14 PM | #215 |
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07-21-2009, 09:43 PM | #216 |
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Interesting thread.
I think we need some new definitions of direction ignition control. Many people are referring to direct as the ability to run some number that can be set in a map somewhere regardless of whether this capability adds any value to the tuning process which it does not. Since the Procede can read DME igntiion timing via CAN, it could actually do direct ignition control going by this definition. All it would have to do is add one different calculation: CAS Offset = Procede Target - DME Actual timing. Then the Procede would have direct timing control. You could enter the timing you want it to run and the engine would run it. Would it actually achieve anything in terms of tuning... no. The truth is that the factory DME has timing maps which already have a shape that is well matched to the engine (with rising ignition advance with RPM and less ignition advance with more boost). The problem is that the piggyback tunes achieve more power by running more boost WITHOUT the DME knowing that the engine has more boost. Anyone who knows anything about tuning knows that as boost rises, ignition advance lowers, but in this case the DME still thinks there is 7psi of boost when the actual boost might be 15psi. So where does this extra ignition retard come from that is required when adding singificantly more boost: * In the case of good high RON race fuels, it is not required. The required ignition advance for 7psi with pump fuel would be about the same as 15psi with say 100RON race fuel. * In the case of a system with CAS phase adjustment, the system can add this extra ignition retard. The shape of the curve is maintained (with respect to RPM), but the curve just has an offset applied to it. The actual ignition advance being run is the same as if the ECU had been correctly mapped for that boost level (hence why "direct" control is not required) assuming the tuner has mapped it well. * In the case of a system without CAS phase adjustment, the DME must make this adjustment by first recognising that it is required. The only sensor that can provide this information is the knock sensor. The knock sensor cannot measure when knock is almost happening. It can only measure when knock IS happening. There is however variable intensity of knock, and it can detect lower levels of knock than are likely to cause immediate damage, and can respond quick enough to prevent damage from prolonged knock. However the knock sensor cannot determine when conditions have changed to allow the ignition advance to be run without knock after it has retarded timing, so the algorithms slowly reintroduce the ignition that has been removed (slowly being seconds rather than milliseconds). When knock starts to occur again, they remove it again. There is likely to be multiple ignition base maps in the DME, and depending on the level of knock activity over a period of time, it may then decide that the fuel RON is lower and enter a base ignition map with lower timing which enables it to be a little closer to ideal timing from the base map. But it will then take a period of time with low knock activity to return to the more agressive base timing map. This may be the adaption people refer to on some tunes. So how much of this less intense knock can the engine take. Well I have seen high quality race forged pistons damaged with severe knock in a short time (seconds) in other applications, and it would likely be the same with the N54 with probably lower quality pistons. With less severe knock, racing pistons can generally run for long periods. In the case of the N54... nobody really knows, and it is still relatively early days. For the user wishing for long reliable service, I guess the best that can be recommended is to minimise duration and severity of knock in whatever way possible to maximise reliability. Also, the longer the engine is run at higher loads and temps, the higher the chance of damage more quickly. Also, a little information on knock sensor systems. They do use a piezo, and it is effectively a microphone with the major difference being that the output bandwidth is tuned to be well matched to typical knock frequencies, and also piezos are more efficient in terms of output voltage and more robust than other types of microphones for the engine environment. The DME has frequnecy filters that then limit the bandwidth to the expected bandwidth of any possible knock. This frequency is typically related to bore diameter. This signal is then input to the main processor in the DME. But it does get a little more complex than this. Knock can typically occur over a short range of the piston movement. Typically this may be about 70 deg BTDC to a fair way ATDC. In a direct injection engine this range would be further limitted by when the fuel is injected. The DME typically takes a sample of the knock sensor level outside of this range , and then a sample inside this range and compares the two. If there is more noise during the knock "window", then it can determine the knock level from how much more. This method has the benefit that a noisy engine (worn bearings etc.) will not false trigger the knock sensor as most other noise will be constant at all engine positions. It also has the benefit that the DME can determine which piston is experiencing the knock from the position of the piston and the knock level. I suspect that the knock status datalog parameter is applied before this piston phase filtering is done, and this explains why it may show knock at very light loads even though knock is all but impossible at light loads. Anyway... just a little more info from my experiences. Of course I cannot categorically claim all this applies to the N54, but all the evidence I have seen suggests this is the case, and I have worked with so many other cars that I do know use these approaches including late model direct injection euros, I would be close to 100% sure this is the case. I actually find it amusing that people think the N54 is some super special engine that runs differently to other engines and that the the DME does things differently to aid a marketting cause when the evidence says otherwise. |
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07-21-2009, 11:06 PM | #217 | |
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07-21-2009, 11:45 PM | #220 |
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