Power Issue in 5th - Comes in Waves

Ryeeno · 08-20-2007, 02:16 PM

Went for a big highway cruise for the first time since Catback and protune (AP) and had this issue.

On the first big uphill section in 5th gear, power dropped way off around 3300 RPMs. On a mild grade the power would come on in waves from 3300 RPM on. Hard to describe. Not a jerky motion but more like a regular, oscillating wave. I tested 4th and 3rd and there was maybe a slightly similar feeling but it was really noticeable in 5th. The more throttle, the more noticeable the waves. WOT would barely lift the RPMs on any level of grade in 5th.

Any ideas?

Stage 2 2002 WRX.

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thummel26 · 08-20-2007, 02:20 PM

gotta be the tune....catback itself wont have anything to do with it.

Master2192 · 08-20-2007, 02:30 PM

Do you have a boost gauge? It sounds like a boost waver, either caused by the tune or changing elevation.

Ryeeno · 08-20-2007, 02:54 PM

I have a boost gauge but it's sitting in the box right now waiting to be installed.

My first thought was boost leak. The RPM spot where it kicked in was right at the usual point where the turbo would kick in. The tune was a few weeks ago and I hadn't noticed anything until that point. Seemed to happen pretty abruptly - like all of a sudden something felt off. Pain in the ass.

mpggomd · 08-20-2007, 03:14 PM

sounds like your boost is waving up and down...are you using the stock controller??

twizzstyle · 08-20-2007, 03:41 PM

Sounds exactly like boost oscillation. Seen lots of people posting about this problem lately, very strange. I had the same thing. I took my boost solenoid off, took it apart and cleaned it with brake cleaner, the problem has never returned.

Boost would oscillate from 17psi to like 12psi, back and forth. Very annoying.

Ryeeno · 08-20-2007, 03:46 PM

Quote:

Originally Posted by mpggomd

sounds like your boost is waving up and down...are you using the stock controller??

Yes, stock controller.

ikhan1999 · 08-20-2007, 05:33 PM

nice thread... i'm having a similar issue (feels like power comes on in waves). I'll keep an eye on this thread.

Ryeeno · 08-20-2007, 06:50 PM

I'm curious about other possible fixes. Also curious about why it's so noticable in 5th, but not other gears.

Frizondizog · 08-20-2007, 07:13 PM

I had the same issue a long time ago, I had a boost gauge tho, Boost was just going back and forth due to a broken vacumn line

vnmvx-0 · 08-20-2007, 07:20 PM

Quote:

Originally Posted by Ryeeno

I'm curious about other possible fixes. Also curious about why it's so noticable in 5th, but not other gears.

probably because in the higher gears, the engine load is greater = more boost required

passion4JC · 08-30-2007, 03:43 PM

Someone solve this boost oscillation problem please! I've been having that too...

AZScoobie · 08-30-2007, 04:05 PM

Boost oscilating issues. Maybe I should right a faq on how to program the boost control system so these tuners can read it and not have this issue. I would gladly fix your map for free but if its a protune its locked and I cant open it. If they will convert to street tuner I would be happy to adjust it for you. I used to have these issues myself. It always shows up in taller gears. The lower the RPM and the load the more pronounced.

Clark

WRXShawn · 08-30-2007, 05:00 PM

I used to have that with an early version of the OTS Cobb stg2 map but with a later version it went away. I had the stock BCS at the time.

passion4JC · 08-31-2007, 12:32 AM

Quote:

Originally Posted by AZScoobie

Boost oscilating issues. Maybe I should right a faq on how to program the boost control system so these tuners can read it and not have this issue. I would gladly fix your map for free but if its a protune its locked and I cant open it. If they will convert to street tuner I would be happy to adjust it for you. I used to have these issues myself. It always shows up in taller gears. The lower the RPM and the load the more pronounced.

Clark

FAQ would be nice.

I forgot to tell you earlier Clark that I'm running a TDC e-tune. Just re-flashed the Cobb Stg2 OTS and the oscillation was even worse.

AZScoobie · 08-31-2007, 01:49 AM

Who wants a fee tune via email? I will remap the car with Cobb or open source and you try it and then you can provide feedback... If you have a protune now it must be converted to street tuner format so I can access it. If your tuner wont do that you are out of luck. Email me your file and I will get on it.

CLark

passion4JC · 08-31-2007, 07:08 AM

me, me, me...i'll try it...

passion4JC · 09-06-2007, 01:41 PM

update...sent my Cobb map to AZScoobie...waiting for the retune...will post feedback...

jigga · 09-06-2007, 04:07 PM

ahh.. I remember this issue... My tuner cured it by changing the pill in the vacuum line and a bit of retuning...

foxboroxt · 09-06-2007, 08:10 PM

You want to see some real boost oscillation, have your big IC crack the nipple off your wastegate! My boost was going from 12 to 20+, very disturbing.

scraggy · 09-07-2007, 12:06 AM

Quote:

Originally Posted by AZScoobie

Who wants a fee tune via email? I will remap the car with Cobb or open source and you try it and then you can provide feedback... If you have a protune now it must be converted to street tuner format so I can access it. If your tuner wont do that you are out of luck. Email me your file and I will get on it.

CLark

Any utec love?

94'325is · 09-07-2007, 10:58 AM

Have you guys tried cleaning your stock BCS? My 03' was doing the exact same thing and I took it off and cleaned it and now I hold 17 psi in all gears. It takes only a few minutes to clean and it makes a huge difference.

passion4JC · 09-07-2007, 01:32 PM

Cleaned the BCS several times. Also cleaned the MAF sensor several times too. Checked all vacuum lines, even cleaned them to make sure...and it is still doing it.

Ryeeno · 10-29-2007, 07:36 PM

Bump this up. Did the email tune work out? Mine is still doing it. Boost goes from 14 - 9 - 14 - 9 in 5th. Flashed back to Cobb Stage 2 93 OTS Map and it's even worse (shows up in 4th).

Tuner says it mechanical and mechanic says it's the tune.

Haelan · 10-29-2007, 08:17 PM

There are many causes for boost oscillations. One thing to check before you start ripping stuff apart...

Do a log on your intake manifold pressure vs. the wastegate duty cycle %. I had a problem overboosting causing an oscillation-type effect (waves of power). If you look below at the bottom you'll see a high duty cycle (70%), it gets to 14.22 PSI, and the ECU says "Oh ****..." and lowers the wastegate duty cycle, but it still climbs another 1.3 PSI before finally settling down.

The problem was MUCH more pronounced in the higher gears. According to my boost gauge my pressure looked spot on, but my ECU is clearly seeing higher pressures than I want it to with a stock map.

What fixed mine: loosening the wastegate arm. You'll lose that immediate power surge in lower gears that feels nice coming off a stop, but you'll have steady boost in higher gears--no more rollercoaster. If anyone reading knows about PID loops, that is essentially what the ECU software is doing to control the boost pressure. The mechanical wastegate arm would apply to the PID Smax and Smin threshold. Depending on how the arm is adjusted creates a 'minimum' boost pressure (mechanical boost)--with all the gains set to 0. The tighter you have that set the more likely your PID loop will overshoot (under-damped). Loosening it too much and you'll be taking forever to build boost and may not hit it at all (over-damped). Having the boost shoot up to the correct PSI as quickly as possible without ringing out is critically damped.

You can fix it with a custom tune to modify your boost map or wastegate duty cycles, and provide a nice stabile boost curve that will be much better than the conservative stock settings.

Just know that blindly tightening your wastegate arm does have consequences and the ECU will not always be able to regulate the BCS to keep boost pressure below it's maximum threshold.

Primary Wastegate Duty Cycle (%) Manifold Relative Pressure (psi)

72.16 11.61
72.16 13.2
70.98 14.22
59.61 15.67
47.45 15.38
41.96 13.78
44.71 12.48
47.06 12.77
47.84 13.35
47.84 13.93

08-20-2007, 02:16 PM	#1
Ryeeno Scooby Specialist Member#: 117161 Join Date: Jun 2006 Chapter/Region: VIC Location: Burnaby Vehicle: '02 WRB WRX '10 Forester XT	Power Issue in 5th - Comes in Waves Went for a big highway cruise for the first time since Catback and protune (AP) and had this issue. On the first big uphill section in 5th gear, power dropped way off around 3300 RPMs. On a mild grade the power would come on in waves from 3300 RPM on. Hard to describe. Not a jerky motion but more like a regular, oscillating wave. I tested 4th and 3rd and there was maybe a slightly similar feeling but it was really noticeable in 5th. The more throttle, the more noticeable the waves. WOT would barely lift the RPMs on any level of grade in 5th. Any ideas? Stage 2 2002 WRX. * Registered users of the site do not see these ads.

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08-20-2007, 02:20 PM	#2
thummel26 Scooby Newbie Member#: 153511 Join Date: Jul 2007 Chapter/Region: E. Canada Vehicle: 2004 STi WR Blue	gotta be the tune....catback itself wont have anything to do with it.

08-20-2007, 02:30 PM	#3
Master2192 RIP 10/12/83 to 02/10/08 Scooby Specialist Member#: 83254 Join Date: Mar 2005 Chapter/Region: NWIC Location: Roy, Washington Vehicle: 98 2.5 RS 04 WRX	Do you have a boost gauge? It sounds like a boost waver, either caused by the tune or changing elevation.

08-20-2007, 02:54 PM	#4
Ryeeno Scooby Specialist Member#: 117161 Join Date: Jun 2006 Chapter/Region: VIC Location: Burnaby Vehicle: '02 WRB WRX '10 Forester XT	I have a boost gauge but it's sitting in the box right now waiting to be installed. My first thought was boost leak. The RPM spot where it kicked in was right at the usual point where the turbo would kick in. The tune was a few weeks ago and I hadn't noticed anything until that point. Seemed to happen pretty abruptly - like all of a sudden something felt off. Pain in the ass.

08-20-2007, 03:14 PM	#5
mpggomd Scooby Specialist Member#: 74167 Join Date: Nov 2004 Chapter/Region: NESIC Location: Tewksbury Vehicle: 2011 WRX Sedan WRB Cobb Stage 2 OTS	sounds like your boost is waving up and down...are you using the stock controller??

08-20-2007, 03:41 PM	#6
twizzstyle Scooby Guru Member#: 18941 Join Date: May 2002 Chapter/Region: NWIC Location: Kenmore, Washington Vehicle: 2005 Lotus Elise Orange	Sounds exactly like boost oscillation. Seen lots of people posting about this problem lately, very strange. I had the same thing. I took my boost solenoid off, took it apart and cleaned it with brake cleaner, the problem has never returned. Boost would oscillate from 17psi to like 12psi, back and forth. Very annoying.

08-20-2007, 05:33 PM	#8
ikhan1999 Scooby Specialist Member#: 94428 Join Date: Aug 2005 Chapter/Region: MWSOC Location: Ex-PDX & Chi-town... Now CO Vehicle: 2002 ???	nice thread... i'm having a similar issue (feels like power comes on in waves). I'll keep an eye on this thread.

08-20-2007, 06:50 PM	#9
Ryeeno Scooby Specialist Member#: 117161 Join Date: Jun 2006 Chapter/Region: VIC Location: Burnaby Vehicle: '02 WRB WRX '10 Forester XT	I'm curious about other possible fixes. Also curious about why it's so noticable in 5th, but not other gears.

08-20-2007, 07:13 PM	#10
Frizondizog Scooby Newbie Member#: 157171 Join Date: Aug 2007	I had the same issue a long time ago, I had a boost gauge tho, Boost was just going back and forth due to a broken vacumn line

08-30-2007, 03:43 PM	#12
passion4JC Scooby Specialist Member#: 46389 Join Date: Oct 2003 Chapter/Region: MAIC Location: Baltimore, MD Vehicle: 2003 WRX Stg 2 PSM	Someone solve this boost oscillation problem please! I've been having that too...

08-30-2007, 04:05 PM	#13
AZScoobie Scooby Guru Member#: 8785 Join Date: Jul 2001 Chapter/Region: SWIC Vehicle: 02 c_turner@ix. netcom.com	Boost oscilating issues. Maybe I should right a faq on how to program the boost control system so these tuners can read it and not have this issue. I would gladly fix your map for free but if its a protune its locked and I cant open it. If they will convert to street tuner I would be happy to adjust it for you. I used to have these issues myself. It always shows up in taller gears. The lower the RPM and the load the more pronounced. Clark

08-30-2007, 05:00 PM	#14
WRXShawn Scooby Specialist Member#: 35742 Join Date: Apr 2003 Chapter/Region: W. Canada Location: Regina, Saskatchewan, Canada Vehicle: 2002 PPG + FPGreen Silver	I used to have that with an early version of the OTS Cobb stg2 map but with a later version it went away. I had the stock BCS at the time.

08-31-2007, 01:49 AM	#16
AZScoobie Scooby Guru Member#: 8785 Join Date: Jul 2001 Chapter/Region: SWIC Vehicle: 02 c_turner@ix. netcom.com	Who wants a fee tune via email? I will remap the car with Cobb or open source and you try it and then you can provide feedback... If you have a protune now it must be converted to street tuner format so I can access it. If your tuner wont do that you are out of luck. Email me your file and I will get on it. CLark

08-31-2007, 07:08 AM	#17
passion4JC Scooby Specialist Member#: 46389 Join Date: Oct 2003 Chapter/Region: MAIC Location: Baltimore, MD Vehicle: 2003 WRX Stg 2 PSM	me, me, me...i'll try it...

09-06-2007, 01:41 PM	#18
passion4JC Scooby Specialist Member#: 46389 Join Date: Oct 2003 Chapter/Region: MAIC Location: Baltimore, MD Vehicle: 2003 WRX Stg 2 PSM	update...sent my Cobb map to AZScoobie...waiting for the retune...will post feedback...

09-06-2007, 04:07 PM	#19
jigga Scooby Guru Member#: 9960 Join Date: Sep 2001 Location: in bed... Vehicle: 2002 Impreza WRX WRBlue Perl	ahh.. I remember this issue... My tuner cured it by changing the pill in the vacuum line and a bit of retuning...

09-06-2007, 08:10 PM	#20
foxboroxt Scooby Specialist Member#: 73104 Join Date: Oct 2004 Chapter/Region: NESIC Location: Mansfield, MA Vehicle: 2003 WRX wagon stg2 2011 Outback	You want to see some real boost oscillation, have your big IC crack the nipple off your wastegate! My boost was going from 12 to 20+, very disturbing.

09-07-2007, 10:58 AM	#22
94'325is Scooby Specialist Member#: 122315 Join Date: Aug 2006 Chapter/Region: South East Location: Tampa/Orlando Vehicle: 2003 WRX OBP	Have you guys tried cleaning your stock BCS? My 03' was doing the exact same thing and I took it off and cleaned it and now I hold 17 psi in all gears. It takes only a few minutes to clean and it makes a huge difference.

09-07-2007, 01:32 PM	#23
passion4JC Scooby Specialist Member#: 46389 Join Date: Oct 2003 Chapter/Region: MAIC Location: Baltimore, MD Vehicle: 2003 WRX Stg 2 PSM	Cleaned the BCS several times. Also cleaned the MAF sensor several times too. Checked all vacuum lines, even cleaned them to make sure...and it is still doing it.

10-29-2007, 07:36 PM	#24
Ryeeno Scooby Specialist Member#: 117161 Join Date: Jun 2006 Chapter/Region: VIC Location: Burnaby Vehicle: '02 WRB WRX '10 Forester XT	Bump this up. Did the email tune work out? Mine is still doing it. Boost goes from 14 - 9 - 14 - 9 in 5th. Flashed back to Cobb Stage 2 93 OTS Map and it's even worse (shows up in 4th). Tuner says it mechanical and mechanic says it's the tune.

10-29-2007, 08:17 PM	#25
Haelan Scooby Specialist Member#: 151045 Join Date: Jun 2007 Location: NW Indiana Vehicle: 2013 Subaru STI CBP	There are many causes for boost oscillations. One thing to check before you start ripping stuff apart... Do a log on your intake manifold pressure vs. the wastegate duty cycle %. I had a problem overboosting causing an oscillation-type effect (waves of power). If you look below at the bottom you'll see a high duty cycle (70%), it gets to 14.22 PSI, and the ECU says "Oh ****..." and lowers the wastegate duty cycle, but it still climbs another 1.3 PSI before finally settling down. The problem was MUCH more pronounced in the higher gears. According to my boost gauge my pressure looked spot on, but my ECU is clearly seeing higher pressures than I want it to with a stock map. What fixed mine: loosening the wastegate arm. You'll lose that immediate power surge in lower gears that feels nice coming off a stop, but you'll have steady boost in higher gears--no more rollercoaster. If anyone reading knows about PID loops, that is essentially what the ECU software is doing to control the boost pressure. The mechanical wastegate arm would apply to the PID Smax and Smin threshold. Depending on how the arm is adjusted creates a 'minimum' boost pressure (mechanical boost)--with all the gains set to 0. The tighter you have that set the more likely your PID loop will overshoot (under-damped). Loosening it too much and you'll be taking forever to build boost and may not hit it at all (over-damped). Having the boost shoot up to the correct PSI as quickly as possible without ringing out is critically damped. You can fix it with a custom tune to modify your boost map or wastegate duty cycles, and provide a nice stabile boost curve that will be much better than the conservative stock settings. Just know that blindly tightening your wastegate arm does have consequences and the ECU will not always be able to regulate the BCS to keep boost pressure below it's maximum threshold. Primary Wastegate Duty Cycle (%) Manifold Relative Pressure (psi) 72.16 11.61 72.16 13.2 70.98 14.22 59.61 15.67 47.45 15.38 41.96 13.78 44.71 12.48 47.06 12.77 47.84 13.35 47.84 13.93