Not hitting target boost, datalog included

deviant94ex · 09-09-2011, 01:40 PM

I have a 2005 92x Aero running Cobb OTS Stage 2 93 v3.00. I have a TurboXS Stealthback with the stock axle-back and a Grimmspeed uppipe.

I am not able to get more than mid 13psi range in 2nd, 3rd, and 4th gears, and hit 14psi in 5th on the highway (albeit with a bit of fine knock correction according to the log). There is no other corrections or anything that I see with a cursory glance of the log in any other gear.

The datalog has a few pulls in it, one in 2nd gear, then shifting into 3rd...then later on a small 4th and a small 5th gear pull I believe. Can you guys take a look and let me know your thoughts.

https://docs.google.com/spreadsheet/...M2ZEE&hl=en_US

Specifically:

1. Anything look out of whack with knock, pulled timing, etc?
2. Would the stock axle-back cause that much boost drop?
3. Does this seem like simply a mechanical issue where I could adjust the wastegate actuator arm length to increase the boost to target levels?

Thanks for the assistance.

Chris

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explosivo · 09-09-2011, 09:25 PM

your DAM is still at 16 so knock isn't that bad. It looks like your hitting your max WGD but boost doesn't appear to be increasing, and your boost target is at 16, so your car should be doing whatever it can to achieve it. Possible boost leak or restriction somewhere? I cleaned my air filter after I wasn't hitting my boost targets when I initially swapped over to a cobb tune and literally boosted 2 psi higher, but my filter was crazy dirty.

People start to increase actuator tension when they max our their WG, I don't know if your car has an adjustable actuator, but you would be better finding the underlying issue rather than trying to tune around it.

Cobb Tuning · 09-10-2011, 08:41 AM

Yes, the stock axleback on these cars is pretty restrictive and you can see reduced boost as a result. Tightening the wastegate arm would be your next step if you believe you are going to keep it. Try half a turn at a time and keep logging. A 3rd gear wide open throttle (WOT) run from around 2000 RPM to near redline (if you can do safely) is a good consistent means of tuning for boost at WOT. The TD boost error will tell you how close you are coming to the actual target (postive values mean you are underboosting by that amount, neg. values you are overboosting). Try to get your peak boost +/- 1 psi of target.

Bill

09-09-2011, 01:40 PM	#1
deviant94ex Scooby Newbie Member#: 55548 Join Date: Feb 2004 Location: Northwest CT Vehicle: 05 Saab 92X Aero	Not hitting target boost, datalog included I have a 2005 92x Aero running Cobb OTS Stage 2 93 v3.00. I have a TurboXS Stealthback with the stock axle-back and a Grimmspeed uppipe. I am not able to get more than mid 13psi range in 2nd, 3rd, and 4th gears, and hit 14psi in 5th on the highway (albeit with a bit of fine knock correction according to the log). There is no other corrections or anything that I see with a cursory glance of the log in any other gear. The datalog has a few pulls in it, one in 2nd gear, then shifting into 3rd...then later on a small 4th and a small 5th gear pull I believe. Can you guys take a look and let me know your thoughts. https://docs.google.com/spreadsheet/...M2ZEE&hl=en_US Specifically: 1. Anything look out of whack with knock, pulled timing, etc? 2. Would the stock axle-back cause that much boost drop? 3. Does this seem like simply a mechanical issue where I could adjust the wastegate actuator arm length to increase the boost to target levels? Thanks for the assistance. Chris * Registered users of the site do not see these ads.

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09-09-2011, 09:25 PM	#2
explosivo Scooby Newbie Member#: 175579 Join Date: Mar 2008 Chapter/Region: SWIC Location: Gilbert Vehicle: 2006 WRX TR OBP	your DAM is still at 16 so knock isn't that bad. It looks like your hitting your max WGD but boost doesn't appear to be increasing, and your boost target is at 16, so your car should be doing whatever it can to achieve it. Possible boost leak or restriction somewhere? I cleaned my air filter after I wasn't hitting my boost targets when I initially swapped over to a cobb tune and literally boosted 2 psi higher, but my filter was crazy dirty. People start to increase actuator tension when they max our their WG, I don't know if your car has an adjustable actuator, but you would be better finding the underlying issue rather than trying to tune around it.

09-10-2011, 08:41 AM	#3
Cobb Tuning NASIOC Manufacturer Member#: 4803 Join Date: Mar 2001 Location: Austin, DFW, Portland, SOCAL	Yes, the stock axleback on these cars is pretty restrictive and you can see reduced boost as a result. Tightening the wastegate arm would be your next step if you believe you are going to keep it. Try half a turn at a time and keep logging. A 3rd gear wide open throttle (WOT) run from around 2000 RPM to near redline (if you can do safely) is a good consistent means of tuning for boost at WOT. The TD boost error will tell you how close you are coming to the actual target (postive values mean you are underboosting by that amount, neg. values you are overboosting). Try to get your peak boost +/- 1 psi of target. Bill