Subaru Forester Owners Forum banner

1 - 20 of 27 Posts

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #1
I've posted a lot recently about the pulsing acceleration that I have under moderate acceleration. This log shows not only a cycling of boost, but also engine rpm. Throttle pressure was held quite constant, and the car does not accelerate smoothly. Automatic transmission in 3rd and didn't downshift. Comments are very welcomed.

2007 Forester XT automatic
Mods:
TurboXS 4" downpipe, catless 3" midpipe, and stock axleback
Cobb stage 2 91 reflash with 91 octane ethanol free gasoline (same symptoms in stage 1 also)
Stock inbox less resonator box, using stock style paper filter.

View attachment 22430
 

Attachments

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #3
No, I haven't. It's really not a stock car at this point...that was my logic at least. It definitely seems like a boost control issue. I don't know how the pills work, etc, but it goes woosh woosh woosh as the car thrusts down the road.
Big boost, loss of boost, big boost, loss of boost until it gets into the 4500 rpm range, then it all smooths out, but I RARELY take the RPM that high because it just doesn't feel good.
 

·
Super Moderator
2007 Forester Sports XT 4EAT
Joined
·
35,883 Posts
I tried running Stage1, which improved performance, but also caused engine cutouts. I was told it was caused by over boosting, a commom problem with the OTS tune. I'm running the married stock map until my scheduled dyno protune, later this month. :smile:

Bobby...

My MODding Journal
 

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #5
I'm sure the flood of "get tuned" responses are just a bit away...
With the wealth of self tuners and mechanical people here, I'm hoping to hear about changing the pill, or something relatively mechanical in nature that I can do without racing to a tuner.
 

·
Super Moderator
2007 Forester Sports XT 4EAT
Joined
·
35,883 Posts
I'm sure there are those that love the OTS tune maps, but you've got to be pretty lucky to have one that closely matches your specific build. :frown:

I'm running almost stock, so I'm going for a dyno protune for the experience, fun & more crap to put in my Member Journal! :biggrin:

Bobby...

My MODding Journal
 

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #7
Yeah, I do agree that OTS maps are junk, but really just using it for the couple months during the build up, hoping to finish up the exhaust shortly, TMIC shortly, and potentially cap it all off with possible turbo and injectors, and then really call it quits and get tuned with the turbo, and injector setup, but really concerned with the current state... Driveability is BAD for VERY basic mods.
 

·
Registered
2004 fxt A/T
Joined
·
2,576 Posts
Remove the pill all together, that will illustrate if it is mechanical. Your WGDC look pretty stable so it doesn't look like a boost control issue. I'm saying leak, more specifically the y-pipe (either the y-pipe itself or at the turbo). That would give the whoosh sound and explain why the ecu is pulling fuel since it thinks more air is getting in.
 

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #9
I did have the intercooler off when I installed the exhaust. I definitely struggled when I re-installed the intercooler, but was happy when it went back together. I do get "full" boost under full throttle, it's just the mid-range that's goofy. There is a very pronounced "whoosh" sound, I left the leak theory alone due to still hitting boost, but you have a good point. Removing the pill, I can do this, just wondering if this is simply a step to diagnose the issue, or permanent?
 

·
Registered
2004 fxt A/T
Joined
·
2,576 Posts
Removing the pill is just to diagnose, if you left it out you would run on WG boost, about 9 psi IIRC. The fact that you are still hitting full boost illustrates even more that it isn't a boost control issue.
 

·
Premium Member
2017 VW Golf SportWagen 5MT
Joined
·
10,887 Posts
I believe you are describing the same choppiness I have. What was the weather like? I think mine gets worse when it's 50 and below.

Stan
 

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #12
Is it possible to still hit boost with a leak? I would assume so. It'll just keep the WG closed or open less to maintain boost, correct?
 

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #13
Yeah, it's warm...it finally hit 50 today! Life in the northern climate!
I know air density plays a pretty big factor in forced induction, but I don't know...Frustrating to say the least.
Stan, have you logged numbers at all with an AP? I should really shoot a video, you guys would not believe it if the video turned out.
 

·
Premium Member
2017 VW Golf SportWagen 5MT
Joined
·
10,887 Posts
Yeah, that one is kinda long.. basically, there are 2 pulls in there, up and down the same empty strip with a u-turn in the middle. I left all the non-WOT stuff in there, it could be cleaned up. I think it was 1st through 4th.

Stan
 

·
Premium Member
2008 FSXT 4EAT
Joined
·
4,161 Posts
My guess is wastegate flutter. Look at the boost and WG duty columns - they're oscillating, which means the WG isn't staying closed. It isn't staying closed because the actuator is meant to operate at lower boost levels.

You can manually adjust the tightness of the WG actuator by disconnecting the actuator arm and turning it. There are some more detailed write-ups on Nasioc on adjusting the actuator.
 

·
Registered
2004 Subaru FXT MT
Joined
·
1,853 Posts
My guess is wastegate flutter. Look at the boost and WG duty columns - they're oscillating, which means the WG isn't staying closed. It isn't staying closed because the actuator is meant to operate at lower boost levels.

You can manually adjust the tightness of the WG actuator by disconnecting the actuator arm and turning it. There are some more detailed write-ups on Nasioc on adjusting the actuator.
Yep, thats where I was going to start...

Did you already tighten the WGA when you installed the TBE? If not, thats the first thing you need to mess with. You want to sneak up on things here, 1 turn at a time. But I think I ended up (and most do) around 2.5-3 turns. You want to shorten the arm, fyi...
 

·
Registered
2007 Forester XT
Joined
·
311 Posts
Discussion Starter #19
Sounds great. I found a big printout from COBB on this, and I'll check NASIOC too. Will this need to be lengthened again for a "return to stock"?
 
1 - 20 of 27 Posts
Top