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Old 11-03-2005, 02:20 PM   #1
greysave
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Default Race gas is causing timing retard

Ok this is a strange problem. I have street tuner with a large turbo setup. I was wondering if having the stock dynamic advance could cause knock or the car to think it is knocking? Dynamic Advance a was tuned by a tuner but advance b and c are set to stock levels. I am hoping this is the problem but am open to input.
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Old 11-03-2005, 07:34 PM   #2
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What are your mods? What kinda race gas are you talkin about?
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Old 11-03-2005, 08:36 PM   #3
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Mods are sr55, modded injectors, tbe, fmic, and all other supporting mods.
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Old 11-04-2005, 02:03 AM   #4
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Are you using a high octane leaded/unleaded race fuel or a mid octane oxy. enhanced fuel?
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Old 11-04-2005, 07:43 AM   #5
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I am using vp 110 leaded. I also tried using c16 with the same result. I will post my data log later today.
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Old 11-04-2005, 07:53 AM   #6
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If only the 'A" map was tuned, there could be somethign weird goign on. For example, maybe the car detects the higher octane and tries to use the 'B' map which is untuned. It depends on what was done, honestly.

From what I've read, the car uses the 'A' map and will try to work it's way up to the 'B' map. If the values in the A map on your car are higher than the B values (which is the opposite of how they are stock), then that might explain your problem.

What you might want to do is take your 'A' map, copy the scaling and values into your 'B' map and then see what happens. If your knock correction doesn't decrease, then that may be, at least part of your problem. You might then want to try adding a bit of timing to the B map in the higher load/higher rpm areas to see if the car will run it.

I still have found very little information on the C map, so I don't know what it does.

Thanks,
Mike

Last edited by crazymikie; 11-04-2005 at 08:05 AM.
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Old 11-04-2005, 08:18 AM   #7
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Quote:
Originally Posted by crazymikie
I still have found very little information on the C map, so I don't know what it does.
I find it incredible that so much time has passed since the release of StreetTuner and Cobb is STILL unable to explain precisely how those maps are used.
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Old 11-04-2005, 09:02 AM   #8
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I wonder if EcuTek has explained these maps to anyone. I'd be very interested to understand them.

In my experience (albeit limited) it is harder to get an STi to run consistently than it is to get a WRX to run consistently. If feels like there is more going on with the ECU and it is constantly trying to optimize things. If the 3 maps aren't set up correctly, it seems like it will be very inconsistent.

Thanks,
Mike
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Old 11-04-2005, 09:13 AM   #9
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Quote:
Originally Posted by Jon [in CT]
I find it incredible that so much time has passed since the release of StreetTuner and Cobb is STILL unable to explain precisely how those maps are used.
I think part of the reason for this is they act different car to car. I swear my car will goto the B-map as a function of coolant temp. Other people see the B-map with higher octane fuel, and still others see the B-map with IAT.

TMS
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Old 11-04-2005, 10:32 AM   #10
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I did a datalog and noticed that from 2300-2400 rpm my timing is 33.0 then around 2450 or so it drops to 6.5 and works its way up. I just feel like maybe my primary ignition table may be off. After reading up a bit Cobb recomends that you rely less on dynamic advance and more on primary ignition. Does anyone have any input on this?
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Old 11-04-2005, 11:19 AM   #11
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Quote:
Originally Posted by TheMadScientist
I think part of the reason for this is they act different car to car. I swear my car will goto the B-map as a function of coolant temp. Other people see the B-map with higher octane fuel, and still others see the B-map with IAT.

TMS
Think back to the days before anyone knew about the two ignition tables in the WRX and how the IAM was used to combine the values. Back then tuners used to piss and moan about how the WRX would alter its timing on them without any apparent rhyme or reason. That is the situation today with the throttle-by-wire ignition advance tables. It only seems like the ECU has car-to-car variability because we lack any understanding of the actual algorithms the ECU is using for selecting and combining ignition advance table values.

Trey Cobb has offered a vague explanation in a PRIVATE communication to a ProTuner user (see http://forums.nasioc.com/forums/show...5&postcount=40):
Quote:
The Knock Correction A, B, and C maps are not something that operate completely independant of eachother. In basic terms table C acts like the single Knock Correction map you find on all other models. A & B work together based on a number of conditions and in turn effect the value provided by the C map.

This is not an easy thing to describe. If you're hoping its something like "Below Condition X it uses Table A, between X and Y it uses Table B, and above Y is uses Table C", you won't be so lucky.

Its more like on some conditions Value from Table A is substracted by the value in Table B, then multiplied by another variable, adjusted by multiple other conditional maps, then based on the value in Table C a variable of the Table A-B calculation is applied to the Table C lookup value.

Once I get more time I'm going to publish a description of exactly how all 3 knock correction maps interact on the STI models but I already know its going to create more confusion than it'll resolve. Some may be hoping for a simple description for a very complex and dynamic system. In the end your best results will come from tuning based on what you're seeing in your datalogs or from the dyno, not by focusing purely on absolute values in the map.

So the basic idea is that they are all dependant on eachother. A&B work directly together and indirectly with C, C being more of the lead character.

Good luck,
Trey @ COBB
From that explanation, anyone seeing their "ECU go into the B map" is completely off-base (out in left field, to be more precise).

I think EVERYONE who owns an STi StreetTuner should start his own thread in Cobb's STi StreetTuner forum asking for a detailed description of how the A, B, and C maps relate and how their values are used to arrive at an ignition advance. Cobb claims such an explanation might confuse people more than they are now. How is that possible? Everyone is COMPLETELY in the dark now.

Oh, and bump your Cobb thread daily with "Bump for explanation." Maybe that'll get their attention.

Last edited by Jon [in CT]; 11-04-2005 at 01:49 PM.
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Old 11-05-2005, 10:25 PM   #12
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I've been thinking about this and I'm starting to think that these maps may work like the CL/OL delay mapping works on the 04/05 WRXs. There are a whole slew of inputs, there is some logic around what all of the inputs are (look at coolant temp, IAT, fuel quality, etc) and based on the values of all of these things, pick some value calculated based on the values in A, B and C.

A scenario like this might explain why different people see changes under different conditions- one person may have a series of inputs satisfied, except for coolant temp. As soon as the coolant temp is above a certain point, it is the last input needed to choose a value in map B.

This doesn't explain things if certain cars ALWAYS seem to move between maps given the same condition, however.


Mike
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Old 11-05-2005, 10:39 PM   #13
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Quote:
Originally Posted by crazymikie
As soon as the coolant temp is above a certain point, it is the last input needed to choose a value in map B.

This doesn't explain things if certain cars ALWAYS seem to move between maps given the same condition, however.
I guess you didn't read Trey's explanation very carefully. He says "If you're hoping its something like "Below Condition X it uses Table A, between X and Y it uses Table B, and above Y is uses Table C", you won't be so lucky." Instead, he says "Its more like on some conditions Value from Table A is substracted by the value in Table B, then multiplied by another variable, adjusted by multiple other conditional maps, then based on the value in Table C a variable of the Table A-B calculation is applied to the Table C lookup value."

He's claiming that Table C is the basic table and that Table A is reduced by the Table B value as part of the adjustment to Table C.
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Old 11-06-2005, 12:14 AM   #14
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Quote:
Originally Posted by Jon [in CT]
He's claiming that Table C is the basic table and that Table A is reduced by the Table B value as part of the adjustment to Table C.
I've talked to Trey about this and I have done my own testing. On an ECU reset on my car my ECU will most definitely use the A map. I have posts illustrating this and have tons of logs that show it. Point for point, it follows A on my car. If knock is detected, it scales back. If it can run at A consistently with no knock then it appears to add fractions of timing and will creep up using B as a maximum.

http://www.iwsti.com/forums/showthread.php?t=32289
http://www.iwsti.com/forums/showthread.php?t=27424

Take a good hard look at the first post. Dynamic Advance A and Dynamic Advance B are exactly the same in all light/medium load areas and all low-mid RPMs. They only differ in the part that needs protection ... and all the values are HIGHER here. It's like somebody copied DA A and just highlighted the bottom right corner of the table and increased the values.

To this day, I haven't seen any data ... at any point in time ... that shows DA C being used at WOT. Maybe at part throttle - but I haven't put ANY time into examining the DA maps with regard to part throttle.

t
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Old 11-06-2005, 09:56 AM   #15
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Quote:
Originally Posted by Jon [in CT]
I guess you didn't read Trey's explanation very carefully. He says "If you're hoping its something like "Below Condition X it uses Table A, between X and Y it uses Table B, and above Y is uses Table C", you won't be so lucky." Instead, he says "Its more like on some conditions Value from Table A is substracted by the value in Table B, then multiplied by another variable, adjusted by multiple other conditional maps, then based on the value in Table C a variable of the Table A-B calculation is applied to the Table C lookup value."

He's claiming that Table C is the basic table and that Table A is reduced by the Table B value as part of the adjustment to Table C.
I saw that, but I was more responding to TMS' point that different cars seem to have different triggers that move them from table to table. More generalized, they may be a set of 'table lookup' functions that use the values in A, B and C and depending on how the input conditions are satisfied, a different lookup function is chosen.

Thanks,
Mike
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