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#26 | |
Scooby Guru
Member#: 8785
Join Date: Jul 2001
Chapter/Region:
SWIC
Vehicle:02 c_turner@ix. netcom.com |
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CT
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#27 |
Scooby Newbie
Member#: 30970
Join Date: Dec 2002
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![]() Tknodav,
Thanks, Hell....For a minute there I thought when I flash the thing I would have to buy a fourpoint!!........Hee,Hee SHotgun |
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#28 |
Scooby Specialist
Member#: 13694
Join Date: Dec 2001
Chapter/Region:
NWIC
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![]() well did you all get your quik road tuning done ?
*try a steady steep hill hardly any brake modulation needed & speeds were reasonable JC |
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#29 |
*** Banned ***
Member#: 10615
Join Date: Sep 2001
Location: sunny so cal
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![]() ok, so shiv, is this really to gain additional power or is this just a short cut for people whom have reset their ecu? would reseting the ecu, then driving it like you stole it for a few tanks allow the ecu to learn and eventaully get the same results?
just trying to figure out what the differences were, if any btw.....what should we name this? i nominate: vishnu reset one more thing, i'll be trying this tomorrow morning, has anyone done it? if so, let's hear some review |
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#30 | |
Scooby Specialist
Member#: 13694
Join Date: Dec 2001
Chapter/Region:
NWIC
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#31 | |
Vendor
Member#: 14494
Join Date: Jan 2002
Location: SF Bay Area, California
Vehicle:WRX Porsche 996 blue & black |
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![]() To answer your question, driving around hard for some time *should* eventually yield the same results. It will happen gradually and the final result will be totally dependent upon the quality of the ECU maps. Too aggressive in fuel, timing or boost maps and you will never see the max Advance Multiplier. FWIW, we do all our ECU mapping with the Advance Multiplier maxed out. This way, the ECU is already at its most aggressive state with little chance for it over-advance itself dangerously as the miles roll by. The Vishnu Reset ( ![]() The same things applies to the stock ECU. In stock cars, we've seen ECU resets result in up to 10hp losses which slowly add back in which each successive dyno pull. Again, this special reset just speeds along the process. Hey, doesn't anyone want to know why this works? I don't think anyone has asked that yet... any guesses? Happy Driving To All, Shiv www.vishnutuning.com Last edited by Vishnu Performance; 01-17-2003 at 03:57 AM. |
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#32 |
Scooby Newbie
Member#: 15073
Join Date: Feb 2002
Location: Canyon Country
Vehicle:2002 WRX Sedan Lotus Seven, A-H 3000 |
![]() does it have anything to do with the transition between open and closed loop?
Lee ps: my car is stonking now ![]() |
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#33 |
Scooby Newbie
Member#: 15306
Join Date: Feb 2002
Location: FRANCE
Vehicle:2011 STi White pearl |
![]() Thanks Shiv,
When you say : "If there are trouble-spots where knock is present, this trick will make it even more present. So be careful!" Won't the ECU retard back again down by 4° in such case ? Or will the ECU keep this maximum advanced timing even if knock is encountered ? |
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#34 | |
Scooby Guru
Member#: 13831
Join Date: Jan 2002
Location: 99 problems but a bitch aint 1
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#35 |
Scooby Specialist
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:2002 Impreza WRX |
![]() Shiv:
Okay I'll hazard a guess. You said not to go on boost before you try this, and I've seen various posts that say the ecu will gradually add timing until it detects knock. If this is a running average of knock correcton, and if the ECU code feels safe giving absolute max possible advance at this low rpm, and boost level, then .... The fastest way to build that running average is to go to the point on the rpm / boost scale the ECU is most willing to give max advance, and hold there long enough to max out the average. Am I close ?? Larry |
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#36 | |
*** Banned ***
Member#: 2992
Join Date: Nov 2000
Chapter/Region:
NESIC
Location: Connecticut, USA
Vehicle:02 WRX Sedan Silver |
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#37 | |
Scooby Guru
Member#: 7089
Join Date: May 2001
Chapter/Region:
NWIC
Location: Western Wa
Vehicle:2016 STi |
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That'd be around 2.7psig, or pounds per square inch gauge, on a boost gauge/meter. |
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#38 |
Scooby Specialist
Member#: 25905
Join Date: Oct 2002
Chapter/Region:
SCIC
Location: San Diego, CA
Vehicle:2003 Silver Wagon Tuned with Enginuity |
![]() Jon, sounds like you've mostly got it, but I've got a few more comments:
It has something to do with experiencing a part-throttle application (low-boost). It also has something to do with keeping the RPMs constant. What I don't quite understand is why this ends up boosting the timing up across the entire rev range, I thought that different RPM ranges were adjusted independantly. (The cause of uneven power delivery under some conditions even on a stock WRX?) Apparently I was mistaken and there is one general timing advance. When knock is detected, it drops timing across the board. This would mean that if you tuned the ECU to run too lean at one particular RPM and the engine knocked, the ECU would drop timing across the board even if the timing you're running is safe at other RPM points. Feel free to correct me if I'm wrong. |
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#39 | |
Scooby Specialist
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:2002 Impreza WRX |
![]() Jon:
Quote:
To clarify, the two possibilities. It could have some ideal timing setting (say 24 degrees BTDC) in its code that it trys to get to if the octane will allow it, or it could always add advance until it determines the current knock limit, and then off sets to a point (say 3 degrees < knock limit timing). Larry |
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#40 |
*** Banned ***
Member#: 2992
Join Date: Nov 2000
Chapter/Region:
NESIC
Location: Connecticut, USA
Vehicle:02 WRX Sedan Silver |
![]() Let me elaborate on my previous post.
Let's assume there are two ignition advance tables which can only be changed by a reflash. Each of these tables is two-dimensional with an idential number of rows and columns, indexed by engine RPM and MAP. Each entry in the first table, which we'll call IGL, represents best ignition advance without knock for low octane gasoline. Each entry in the second table, which we'll call IGH, represents best ignition advance without knock for high octane gasoline. The ECU will never advance the ignition beyond IGH table values and never retard the advance below the IGL table values. Now let's takes Shiv's Ignition Advance Multiplier (IAM), which he says ranges in value from 1 to 16, and form another scalar, called e, which ranges in value from 0 to 1: e = (IAM - 1) / 15 e is used to form a "rough correction quantity," which we'll call AT, in the following way: AT = IGL + e * (IGH - IGL) In other words, AT is an interpolation between the low octane timing advance and the high octane timing advance. When e is zero (i.e. when IAM is one), the low octane timing is used and when e is one (i.e. when IAM is 16), then the high octane timing is used. Otherwise, a timing somewhere between the low and high octane timing is used. There is also a table of learned "fine correction quantities," which we'll call AP, with the same dimensions as IGL and IGH, above. Final learned ignition advance (IGTL) is: IGTL = AT + AP Assuming that IGTL is greater than IGL and less than IGH, it becomes the actual ignition advance. The timing learning mode conditions (see my previous post) were selected to insure reliable knock detection - RPMs greater than 5000 means more engine noise and low engine load means low knock sensor output. When timing learning mode is active, the ECU has a timer going. Every second or so the timer pops and the ECU checks to see whether there has been any knock during the interval, If not and if the IAM is not yet set to its maximum value, then it's incremented by 1. However, if, during the previous period, the number of knock events exceeds a threshold, then the IAM is decremented by a number, let's say 2. If the knock count is greater than zero but less than the threshold, then IAM remains unchanged. Whenever the IAM is changed, the fine correction table, AP, is zeroed out. If a knock event doesn't cause a change in IAM, then the appropriate fine correction table entry is adjusted. P.S. So, If what I've written here is correct, it should take a full 8 seconds (not 5 seconds) for the Ignition Advance Multiplier (IAM) to change from its initial value of 8 to its max value of 16, assuming no knock. ![]() Last edited by Jon [in CT]; 01-17-2003 at 06:51 PM. |
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#41 |
Scooby Specialist
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:2002 Impreza WRX |
![]() Jon;
Great info. So based on that then the short answer to my question above is the ECU attempts to get to a preprogrammed hard coded ideal advance for high octane fuel (or as close to that number as the algorthm will allow). edit -- ( at least in any given cell of the table, so there is not a global fixed max timing, but a max in each cell) This is an important non-trivial distinction vs the off set scenario for the following reason. If this fixed advance max scenario is correct, then there is some octane of fuel that will give you the maximum possible ignition advance the ECU is allowed to give. In that case once you exceed that ideal octane level you will gain no more advance, and with the exceptions of a cushion of octane for changing conditions and possible differences in burn characteristics, going to a higher octane fuel will have no effect on advance and probably horse power. If the off set scenario was the correct behavior of the ECU, then you could in effect tune the ignition timing the ECU would give you by finding the fuel octane that gave the mechanically ideal ignition advance. Last -- although I think I know the answer just to be absolutely clear, are the algorthms you posted above, known to be true (at least in general behavior if not in exact construct) or are they hypothetical for the purposes of the discussion? Larry Last edited by hotrod; 01-17-2003 at 07:06 PM. |
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#42 |
*** Banned ***
Member#: 2992
Join Date: Nov 2000
Chapter/Region:
NESIC
Location: Connecticut, USA
Vehicle:02 WRX Sedan Silver |
![]() I stole the algorithms from FHI's US Patent 5,000,149 because they seemed to fit (after scaling Shiv's Ignition Advance Multiplier to the patent's e) the little bit of actual data offered by Shiv. I have no idea of whether the WRX's ECU uses anything even remotely similar to what I've written.
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#43 |
Scooby Specialist
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:2002 Impreza WRX |
![]() That's pretty much what I thought, as I knew you liked to dig into the patent files.
I would guess they are very close, with maybe some trivial additonal variables thrown in etc. At this point someone with a dyno could take those relationships and play with different fuels and either validate them or demonstrate exceptions. My guess based on my previous experience and what you've added here is from a performance point of view the improvements above 104 octane will be small, except for those running high boost and with on the edge tuning. In that case they probably do not rely on the stock ECU anyway. If how ever one of the folks who can do ECU reflashes wanted to they could optimise a reflash high octane map for 112 or above, with a low octane map at typical values to give the ECU more dynamic range. I love puzzles !! Larry |
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#44 | |
Scooby Specialist
Member#: 25905
Join Date: Oct 2002
Chapter/Region:
SCIC
Location: San Diego, CA
Vehicle:2003 Silver Wagon Tuned with Enginuity |
![]() Quote:
Interesting that FUJI filed that patent you reference back in 1991! I wonder how long they've been using it? Given light of this information, do you think that Vishnu's ECUTEK mapped ECUs still have the low-end map capable of running crappy fuel? I'd had to get a crappy tank of fuel (or someone fills it with 87 on accident!) after a reflash and have the engine detonate to bits because the mapped ECU no longer has the adjustment range to back off enough. Now knowing this info, it seems that I was correct in thinking that the ECU does adjust timing parameters over specific RPM ranges. But it that general adjustment map seems to affect performance the most. It would be interesting to learn Shiv's general strategy when designing the various maps what what they change to get so much more power over stock. |
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#45 | |
Scooby Specialist
Member#: 14141
Join Date: Jan 2002
Location: [email protected] @ 5800 ft on 13T
Vehicle:2002 Impreza WRX |
![]() Quote:
For example, if a tuner changes the mixture or boost profile at high rpm, does the ECU just require a much stronger signal at high rpm to pull timing? Larry Last edited by hotrod; 01-18-2003 at 01:16 AM. |
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#46 |
*** Banned ***
Member#: 2992
Join Date: Nov 2000
Chapter/Region:
NESIC
Location: Connecticut, USA
Vehicle:02 WRX Sedan Silver |
![]() Some other observations.
It appears that the stock ECU's load reference for ignition timing is, crudely, boost. It appears that ignition advance determination depends, ultimately, on the input from only three sensors: Crank angle position sensor (for engine RPM) Manifold absolute pressure (MAP) sensor Knock sensor It appears the ECU ignores other sensors which folks here have speculated are an influence on timing advance: Mass air flow (MAF) sensor Throttle postion sensor Intake air temperature (IAT) sensor I know, for instance, that RiftsWRX believes strongly that intake air temperature plays an important role in determining ignition timing advance, so strongly that he was able to persuade the UTEC designers to include it as a timing advance modifier in the TurboXS UTEC piggyback. And to Shiv (who asked: "Hey, doesn't anyone want to know why this works? I don't think anyone has asked that yet... any guesses?"): I'll bite. I'm asking: why this works? And please don't be shy in the future about sharing other observations/tips about how the stock ECU really works, now that you can see it internals. P.S. Shiv, if I have guessed more or less correctly, am I the lucky winner of an ECUTEK Stage 2 from Vishnu? ![]() |
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#47 |
Scooby Specialist
Member#: 13025
Join Date: Dec 2001
Chapter/Region:
RMIC
Location: Longmont, Colorado
Vehicle:1998 RS-T Rally Blue |
![]() Yeah, why does this trick (shiv reset) work. Also, how did you come up with it? And thanks for it.
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#48 | |
Scooby Guru
Member#: 13831
Join Date: Jan 2002
Location: 99 problems but a bitch aint 1
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![]() Quote:
The stuff that hotrod talked about with octane is great too. Right after you fill up with high octane before some motorsports event, do a quick ecu reset in this fashion and if everything else is in proper working order youre basically guaranteed the best performance your car can give ![]() |
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#49 | |
Scooby Guru
Member#: 8785
Join Date: Jul 2001
Chapter/Region:
SWIC
Vehicle:02 c_turner@ix. netcom.com |
![]() Quote:
Anyone who has used an SAFC on a WRX while monitoring a Delta dash can clearly see that MAF input effects ignition advance. The more fuel is removed with the SAFC(less MAF input voltage at the ECU) the more advance ramps up. In cases where the fuel system is far overkill for the application and alot of negative fuel correction is needed on the SAFC Ignition advance can rise to the point that its to much and knock is induced. Greg (Turborex) as spent hours datalogging this behavior and can offer more insight. I have yet to try this reset trick but will datalog with delta dash my advance curve before and after the reset/trick. It will be interesting to see the final results. I found Shivs post interesting because I have been using this trick for about a year now without knowing what I was doing and or why it was working. I discovered this trick while drag racing. I noticed on a reset ECU my times would drop. This was back before the delta dash existed so I was guessing as to what was causing the power loss. While experimenting and pulling a few ideas of posters on this forum I found that reseting the ECU and then running wastegate boost on the way to the track before boosting up high would always net a faster time. Add race fuel, Reset ECU, Turn boost down to 8psi, Drive to track, turn boost up.... I posted that suggestion many times to drag racers on the forums. Now I know why it worked. Clark Last edited by AZScoobie; 01-21-2003 at 12:08 PM. |
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#50 | |
Scooby Newbie
Member#: 14076
Join Date: Jan 2002
Location: San Diego
Vehicle:2003 WRX Sedan WRB |
![]() Quote:
I also see less MAF voltage equals less "air flow" (what the ECU thinks), thus shouldnt the natural reaction of the ECU be to advance timing to improve off/low/none boost performance. Wouldnt the ECU think that you're a lower RPM and adjust accordingly? |
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