APS DR525 Results, Tuning, etc. - Page 15

stretch · 03-20-2007, 08:25 AM

Just read through the entire thread again... what a fantastic read. I do think the "MAF delay" seems to be the most likely cause of your problem, but I have one more idea I don't think you've tried.

Wolf, if you're running an APS intake, could the problem be stemming from the MAF being after a multiple bends (one very sharp)? This is going to create a lot of turbulence in the intake air (which your rescaled MAF calibration has hopefully compensated for), however, what if the amount of turbulence is different on spool-up, while the air in the tube itself is quickly accelerating? The dynamics of air flow after a sharp bend are quite wild. It seems like a longshot, but hey, it's something new to think about that goes back to the MAF calibration.

You might consider throwing the stock airbox on (Will it fit upside down with the hood open? Be createive!), zero out the MAF correction, and see if anything changes. You should be able to tell just blipping the throttle with the car parked and would eliminate the MAF calibration as a cause for sure.

crystal_Imprezav · 03-20-2007, 11:44 AM

I have gone through a lot of code and frankly there isnt a lot there to pick at with the MAF. I am pretty sure there is no delay value. I tweaked some other tip-in values however it only helped when in closed loop. I am going to test blow-through to see how it holds up. I think speed density is probably the way to go to help this cause.

lackskill · 03-20-2007, 11:50 AM

Quote:

Originally Posted by crystal_Imprezav

I have gone through a lot of code and frankly there isnt a lot there to pick at with the MAF. I am pretty sure there is no delay value. I tweaked some other tip-in values however it only helped when in closed loop. I am going to test blow-through to see how it holds up. I think speed density is probably the way to go to help this cause.

So there is a reason that the maf sensor is the distance from the TB that it is.

RainMaker · 03-20-2007, 05:52 PM

Quote:

Originally Posted by crystal_Imprezav

I am going to test blow-through to see how it holds up.

Been there, done that.

crystal_Imprezav · 03-20-2007, 07:21 PM

Yea I feel you, but at this point I am willing to try anything to get the car running better.

RainMaker · 03-20-2007, 07:35 PM

Quote:

Originally Posted by crystal_Imprezav

Yea I feel you, but at this point I am willing to try anything to get the car running better.

Been there, done that too....

Speed density is that last hope for those over 375 awhp, as far as I know.

stretch · 03-21-2007, 09:46 AM

Quote:

Originally Posted by crystal_Imprezav

Yea I feel you, but at this point I am willing to try anything to get the car running better.

Perhaps this is another compelling reason for a water to air intercooler? FMIC cooling but without the increase in intake volume.

lackskill · 03-21-2007, 10:25 AM

Quote:

Originally Posted by stretch

Perhaps this is another compelling reason for a water to air intercooler? FMIC cooling but without the increase in intake volume.

Reverse intake VMIC for less than $3k would be cool too.

04stiguy · 03-29-2007, 11:00 PM

Quote:

Originally Posted by RainMaker

Been there, done that too....

Speed density is that last hope for those over 375 awhp, as far as I know.

FWIW......

Up until recently, I put off going to blow thru based on many negative posts on this board and NASIOC. I just got fed up with the issues I was having with the "rich spike" and part throttle high boost MAF turbulence I would get from the BPV when configured in draw thru mode. I don't know if I happened to get lucky and placed it in just the right spot, but IMO, the blow thru MAF is the only way to go when you have a large volume FMIC. I have been daily driving with it for a few weeks and I have nothing put positive fedback. Drives just like stock.

R4ND0M_AX3 · 04-02-2007, 11:43 AM

I thought this was interesting.
http://www.cobbforums.com/forums/showthread.php?t=31091
Regarding setting the Fuel Injector Boost Error Trim (FIBET) table.

Quote:

Originally Posted by From Christian.'s fuel injector doc

IF YOU ARE RUNNING WITH A FRONT MOUNT INTERCOOLER, WE SUGGEST YOU SET ALL OF THESE VALUES TO ZERO
(see below table). This helps prevent the over-fueling if the engine due to the time delays associated with having the MAF located further
away from the throttle body.

WolfPlayer · 04-02-2007, 01:27 PM

Quote:

Originally Posted by R4ND0M_AX3

I thought this was interesting.
http://www.cobbforums.com/forums/showthread.php?t=31091
Regarding setting the Fuel Injector Boost Error Trim (FIBET) table.

Both daemon and I have our FIBET set to zero and still see crazy rich spikes. Changing the FIBET does nothing on my car. Definitely try setting the FIBET to zero (which is covered very early on in this thread), but don't be surprised if it doesn't do anything for your car.

t

R4ND0M_AX3 · 04-02-2007, 03:28 PM

Quote:

Originally Posted by WolfPlayer

Both daemon and I have our FIBET set to zero and still see crazy rich spikes. Changing the FIBET does nothing on my car. Definitely try setting the FIBET to zero (which is covered very early on in this thread), but don't be surprised if it doesn't do anything for your car.

t

I don't have a front mount but the newest worksheet from christian says I should be using zeros instead of 30's that I had in there because of teh PE850s.

I did reread the whole thread and noticed that you tried 0s but where later back to something else.

I just thought it was intereseting that it's now an open recomendation for FMICs. (from COBB anyway).

I just got back from my local protuner with a my table updated. Please COBB, stop asking us to change things we dont have access to change.

flatthump · 04-02-2007, 03:31 PM

crystal_Imprezav · 04-02-2007, 09:09 PM

No go, been there done that one too.

04stiguy · 05-13-2007, 09:10 PM

Quote:

Originally Posted by 04stiguy

Fourth gear.

FWIW, here is updated data using blow-thru. Very satisifed with how the car runs now.

This is the first turbo Subaru I have tuned. I would welcome some expert opinions from those who have tuned a rotated GT car on California 91 octane. Not sure what kind of timing I can get away with.

I think I could step up the curve, but not sure how much.

03-20-2007, 08:25 AM	#211
stretch Silver Member Car: Aspen 2005 STi Fav Mod: TurnInConcepts.com Coilovers Location: Silver Spring, MD Posts: 1,811 Join Date: Mar 2006 Trader Rating: (2)	Just read through the entire thread again... what a fantastic read. I do think the "MAF delay" seems to be the most likely cause of your problem, but I have one more idea I don't think you've tried. Wolf, if you're running an APS intake, could the problem be stemming from the MAF being after a multiple bends (one very sharp)? This is going to create a lot of turbulence in the intake air (which your rescaled MAF calibration has hopefully compensated for), however, what if the amount of turbulence is different on spool-up, while the air in the tube itself is quickly accelerating? The dynamics of air flow after a sharp bend are quite wild. It seems like a longshot, but hey, it's something new to think about that goes back to the MAF calibration. You might consider throwing the stock airbox on (Will it fit upside down with the hood open? Be createive!), zero out the MAF correction, and see if anything changes. You should be able to tell just blipping the throttle with the car parked and would eliminate the MAF calibration as a cause for sure. This ad is not endorsed by this member. Please register or login to hide this ad. Last edited by stretch : 03-21-2007 at 10:47 AM.

03-20-2007, 11:44 AM	#212
crystal_Imprezav Spec C Club Car: Slow 05 STi Fav Mod: Loping Idle Location: Chewy's Garage Posts: 1,878 Join Date: Mar 2005 Trader Rating: (12)	I have gone through a lot of code and frankly there isnt a lot there to pick at with the MAF. I am pretty sure there is no delay value. I tweaked some other tip-in values however it only helped when in closed loop. I am going to test blow-through to see how it holds up. I think speed density is probably the way to go to help this cause.

03-20-2007, 07:21 PM	#215
crystal_Imprezav Spec C Club Car: Slow 05 STi Fav Mod: Loping Idle Location: Chewy's Garage Posts: 1,878 Join Date: Mar 2005 Trader Rating: (12)	Yea I feel you, but at this point I am willing to try anything to get the car running better.

04-02-2007, 03:31 PM	#223
flatthump Enginerd Car: The Spaze Mobile Fav Mod: Tuning Location: South O.C., Ca Posts: 13,019 Join Date: Jan 2006 Trader Rating: (5)	^

04-02-2007, 09:09 PM	#224
crystal_Imprezav Spec C Club Car: Slow 05 STi Fav Mod: Loping Idle Location: Chewy's Garage Posts: 1,878 Join Date: Mar 2005 Trader Rating: (12)	No go, been there done that one too.