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Old 07-09-2013, 02:03 PM   #1
AcquaCow
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Default 04 STI OL MAF Scaling Prereqs? My curve looks strange...

Hi,

I've finished several passes of closed loop scaling and have that pretty well dialed in, but my open-loop isn't a nice curve the way I've been led to expect.

Car is an 04 STi, stock injectors, Injen AEM 65mm CAI, APS 3" turbo inlet, equal length headers, and 1-cat turboback exhaust.



I'm not sure what is causing the curve change from 3.5-4. I originally ignored it and smoothed it into a normal-looking curve, but on the next pass of OL logging, all the data says the curve is correct. I'm within 3% of the AFR table with that curve, but everything I've read tells me I shouldn't have a curve like that.

Some folks have mentioned AVCS affecting it, but I haven't seen anything that said to zero out AVCS before scaling MAF/etc..

Thanks,

-- Dave
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Last edited by AcquaCow; 07-09-2013 at 05:42 PM.
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Old 07-09-2013, 03:08 PM   #2
Frank_Zuccarini
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I show a similar, though less severe, 'zig-zag' at about 4.4V. Derived by countless Open Loop runs with a WB O2 Monitor.

I've always assumed that it has something to do with CL to OL switching, or possibly a delay between when the exhaust gas passes the O2 sensor and my AccessPort records the output, but I don't know.

I'll stay tuned for whatever we learn.

Frank
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Old 07-09-2013, 05:44 PM   #3
AcquaCow
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Hmm, just decided to go look at the CAI...





It's not an Injen afterall... this changes a few things, but not my original question... Cobb has scalings for this intake on their site, but not for the 04... so I can't open the map in accesstuner w/o a valid basemap to compare numbers... grr.
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Old 07-10-2013, 07:49 AM   #4
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Lots of things can change measured AFR at the tailpipe. That 'lump' in the MAF scaling isn't correct.
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Old 07-10-2013, 07:54 AM   #5
AcquaCow
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AFR was measured behind the turbo, before the cat.
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Old 07-10-2013, 04:35 PM   #6
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Random thought for sure but.......ive never seen a MAF mounted sideways.


After a tune it would be fine but the way it is sitting may be affecting the scaling a little. Strictly speaking out my ass here, just thought it looked different then noticed its not sitting on top lol
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Old 07-10-2013, 07:16 PM   #7
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Either that or you may have a small boost leak, which would explain the dip.
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Old 07-10-2013, 10:27 PM   #8
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Well, I picked up a different intake today (APS 65mm), will build a boost-leak test kit before I put it on and check the manifold/etc for leaks before I install it.

-- Dave
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Old 07-11-2013, 09:31 AM   #9
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I have tuned several AEM intake cars that look like that. I HATE these intakes...
OP, looks like you scaled it appropriately for what it is...

Steve @ Pullz-On Tuning
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Old 07-11-2013, 10:31 AM   #10
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You may want to try grounding the intake. As I know the newer GR AEM intakes need to be grounded properly to prevent the MAF getting noise into its signals. Plastic stock intake does the for us already, and alot of intakes out there are coated, but the all metal ones can cause issues like this.
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Old 07-11-2013, 04:14 PM   #11
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This is interesting^^ I've heard this a long time ago but never really paid it any attention.

Steve @ Pullz-On TUning
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Old 07-22-2013, 11:35 PM   #12
AcquaCow
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Used the boost leak tester... ramped it up to 12psi with no leaks...pretty sure that isn't the issue...


So out with the AEM and in with the APS...


It was a tight fit on a GC, but somehow I managed to get the filter on it.



Somehow it all fits...



I found a curve on romraider forums that I'll richen up and start with... see if I get a proper scaling out of this...

I'll report back.

-- Dave
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Old 07-30-2013, 02:00 AM   #13
AcquaCow
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Well, been scaling the APS finally...with an odd result..

New thread here:
http://forums.nasioc.com/forums/show....php?t=2534098

Thanks,

-- Dave
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Old 08-03-2013, 02:03 AM   #14
AcquaCow
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Re-scaled with an APS intake...

Mostly stock MAF curve in blue, pink is my resulting APS curve... much nicer than the AEM...
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Old 08-15-2013, 10:29 AM   #15
AcquaCow
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Hmm, did some more logging as I saw myself running a tad rich in a place or two... maf curve is starting to develop that S shape around 4v again...not anywhere nearly as severe, but there's still something there...

-- Dave
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