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Go Back   IWSTI.com: Subaru STI Forums > STi Technical Discussion > ECU Tuning & Performance Electronics > Cobb Street Tuner


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Old 07-25-2005, 05:57 PM   #1
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Default Even more Newb ST questions.

Ok, I've got some newbie questions about Streetuner. I've been reading their help, and studying the stage 2 v1.04 tables.

Here we go:

1. I've noticed, as WolfPlayer has said in his guide, that many of the calculated loads stop at 2.75. Lets say I've got all the bolt-ons (which I basically do ), and I hit 3.25. Does that mean I'm simply running where 2.75 left off? Is there danger in this, or, just alot of power left on the table?

2. The primary ignition maps only go to 2.75, yet, the dynamic advance goes to 2.90? How will that ever be used? I mean, there isn't a primary column at that load to add advance to...

3. Why do most Throttle Position columns only go to 80%? Is 100% interpolated or something? Probably a simple answer to this, but, hard searching on 80% in the forums.

4. The DAM, this is at .5 by default. But... Does this value go to 1 if no knock is detected, or, conversly, to less than .5 if knock is detected? Meaning, you'll be running your entire amount of dynamic advance specified in the Dynamic Advance Table A/B/C if no knock is detected? If so, why even have a starting point? I suppose this allows for more performance on a knocking engine...

Thanks to all for any replies, and I apologize in advance for my Newb questions.


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Old 07-26-2005, 04:20 AM   #2
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1) Yes. It uses the 2.75 values. Danger? Yes (although not as much with the stock Cobb map). When you begin tuning for power you'll see that you have to take a lot of fuel out of that 2.75 column (stock type intake). This puts things on the edge and you need to be in control of fuel and timing

2) The 2.75 column just continues out. So, when you are running 3.0 load it uses 2.75 primary ignition and 2.9 dynamic.

3) They assume that if you are at 80% then you are at WOT. No need for more resolution. How often are you at 90%? I don' think I ever really am.

4) Yes to your initial questions. The value of 0.5 is used because this is the median value between performance and total crap Start in the middle and figure out which way to go. Lots of ECUtek tuners and Vishnu change this to 1.0. I can see why they do this ... because as soon as I reset the ECU the first thing I always do is bring the DAM up to 1.0 by the trick I mentioned (Vishnu trick).

t
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Old 07-26-2005, 07:30 AM   #3
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I guess I'm still confused on this question though:

2. The primary ignition maps only go to 2.75, yet, the dynamic advance goes to 2.90? How will that ever be used? I mean, there isn't a primary column at that load to add advance to...


If I understand correctly, the primary ignition tables are the base for what timing to use. So, lets just take a cell for an example from v1.04 stage 2:

(lets assume IAM is 1)
Advance Table A says at a load of 2.90, at 4400 RPM, the ECU will add 3.18 degrees of timing.

Now primary IGN map:

4400 RPM/Calc Load only goes to 2.75. Will the ECU simply add 3.18 to whatever is in the last column at that RPM? So, in this case, 11.64+3.18?

Or, will it never be able to add any timing at 2.90, because there simply isn't a value in the primary maps that resides at [2.90:4400]?
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Old 07-26-2005, 08:46 AM   #4
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In the base ignition map ... for whatever load you are at beyond 2.75 ... it uses the 2.75 value. So, if you are at 3.0 load then is just uses the value specified at 2.75.

Examples:
2.50 load = uses 2.50 load column from main ignition and 2.50 load from dynamic
2.75 load = uses 2.75 load column from main ignition and 2.75 load from dynamic
2.90 load = uses 2.75 load column from main ignition and 2.90 load from dynamic
3.00 load = uses 2.75 load column from main ignition and 2.90 load from dynamic
3.10 load = uses 2.75 load column from main ignition and 2.90 load from dynamic

When going past the values specified in the tables then the ECM will use the last column. This is the same with the RPMs too. If you ran your motor up to 9000 rpms then it would use the values specified at 7600.

All of this is sort of moot anyhow. Why? Because all of us ST users desperately need to modify our tables to support up to 3.25 load. I still can't believe that Cobb supplied the maps in this fashion given that the Stage II basemap will often give values of 3.10.

t
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Old 07-26-2005, 09:04 AM   #5
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Where do you live WolfPlayer? Just curious because since I've been using ST I haven't been able to get to a load of 3.0 at stage 2. Except for when I threw on an Apexi intake and was mightly surprised at the high loads I was hitting until I realized it was seriously tricking the MAF. Now that I have it tuned back to reality, I'm back to not being able to hit or break 3.0. Of course it is pretty darn hot here right now (Florida). Maybe in the winter.

Wonder if my headers have anything to do with it... Hmmm... And I also haven't attempted to tune the area where max load generally occurs for me yet. But it certainly hasn't happened with the stock stage 2 map.
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Old 07-26-2005, 10:22 AM   #6
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Quote:
Originally Posted by WolfPlayer
In the base ignition map ... for whatever load you are at beyond 2.75 ... it uses the 2.75 value. So, if you are at 3.0 load then is just uses the value specified at 2.75.

Examples:
2.50 load = uses 2.50 load column from main ignition and 2.50 load from dynamic
2.75 load = uses 2.75 load column from main ignition and 2.75 load from dynamic
2.90 load = uses 2.75 load column from main ignition and 2.90 load from dynamic
3.00 load = uses 2.75 load column from main ignition and 2.90 load from dynamic
3.10 load = uses 2.75 load column from main ignition and 2.90 load from dynamic

When going past the values specified in the tables then the ECM will use the last column. This is the same with the RPMs too. If you ran your motor up to 9000 rpms then it would use the values specified at 7600.

All of this is sort of moot anyhow. Why? Because all of us ST users desperately need to modify our tables to support up to 3.25 load. I still can't believe that Cobb supplied the maps in this fashion given that the Stage II basemap will often give values of 3.10.

t
Awesome! Thanks for the answers. Kinda what I thought, but, was just checking.

I'm getting some logging tonite, and sending them off to Dave Hall for his suggestions.

Quote:
Originally Posted by daemon

Just curious because since I've been using ST I haven't been able to get to a load of 3.0 at stage 2.
I'll be logging tonite as well, we'll see what I get up to. I'll be looking for max values at torque peak..

Which brings up another newb tuning question!!!

If your tune is good, can it increase the engine load, thus making it possible that you need to tune for more engine load, and so on and so on?
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Old 07-26-2005, 10:38 AM   #7
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I have to take back a little of what I wrote. I just looked at a log from this morning and noticed I hit 3.0 even! 3.25 here I come.

And yes, the tune can effect engine load. You just need to be sure all areas in your map are safe enough. If you take it slowly then you won't run into a huge oscillating effect where you have to make large adjustments because of your adjustments, etc.
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Old 07-26-2005, 10:54 AM   #8
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Sounds like you are on the right path now.

I live in Maryland ... around Sea Level. Check out your boost where you are hitting 3.0. If it is not hitting ~17.5 then you aren't even at max boost for Cobb which means that when the weather gets colder and you can reach max boost then it will most definitely go up (it will go up in colder weather anyhow due to the cooler charge temp).

I'm running a modified stock intake. I removed the resonator. Installed an STI air filter, Samco MAF hose, and a 3" velocity stack in the fender.

t
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Old 07-26-2005, 11:41 AM   #9
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Where did you get the fender velocity stack from? I recall seeing it somewhere a long time ago.

I'm having no problems hitting boost. When do you usually hit peak boost when starting from sub-3000 (and what gear) and what are you peaking at?
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Old 07-26-2005, 12:45 PM   #10
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Quote:
Originally Posted by WolfPlayer

I'm running a modified stock intake. I removed the resonator. Installed an STI air filter, Samco MAF hose, and a 3" velocity stack in the fender.

t
I have also removed the snorkel and am using a higher flow panel filter. I don't have the velocity stack.

Have you actually changed the intake calibration in the fuel tables? Since the diameter didn't change in the housing, I wouldn't think its required...
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Old 07-26-2005, 06:07 PM   #11
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daemon - I got the velocity stack from Summit Racing. I got the idea from ScoobyMods. Here are my pics: http://www.bescaredracing.com/sti/in...ncer/velocity/

drfrink24 - You wouldn't think it is required ... and who knows, maybe it isn't. I never performed any scans before doing my intake mods. I purchased ST afterwards. I do know that the IDLE long term fuel trims were off by 4-6%. Part Throttle fuel trims still remained at zero.

t


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