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Old 04-28-2013, 08:46 PM   #1
RodThe3inchKiller
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Join Date: Apr 2013
Default only 5 psi of boost. adjusting waste gate actuator arm?

hello new to the site. im struggling to find out why my boost is so low.i have a 02 wrx with cobb downpipe, borla cat back, catless uppipe, and cobb AP. Im using the stage 2 93 oct. map. Im currently only running 5-7 psi and at the most.

so this is what ive done so far... ive checked the BCS by connecting it to bat..it works...checked for the pill...its there. connected my intake to an air compressor at 20 psi. didnt find any leaks... I dont think the exhaust is leaking before the turbo. i rev it up and i dont feel anything blowing by at all the junctions.

the previous owner had the dealer put a new turbo in it few years back because of the cat breaking up. So im thinking could they have not set the actuator arm to the proper tension idk. im thinking about adjusting it. How do i check for proper tension? Can anyone think of any other tests?
Also here is some logged data. does every thing look normal? I dont really have a baseline for what these should be reading
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Old 04-28-2013, 09:05 PM   #2
the suicidal eggroll
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Default

Low knock, good DAM, WGDC>0, so you can scratch a disabled boost control system off of the list. However, your AFRL is pretty high at 9.4% at the start of the log, you might want to look into that.

Anyway, since you've already eliminated a disabled boost control system and boost/exhaust leaks as the culprit, the next thing I would do is remove the reference line from the wastegate actuator and go for a drive. Be VERY careful as you get on the throttle, watch the boost gauge religiously. Without the boost reference line in the mix, the wastegate SHOULD never open, which means your boost should rise until it hits the turbo's limits well into the 20 psi range. So if you see the boost breaking 15 psi then back off the throttle.

If you run high boost during this test, then everything is fine mechanically and you could try tightening the wastegate arm a slight amount. If you still run ~5 psi during this test then you should check again for leaks or possibly a dead wastegate. You could also be running so rich that you don't have the energy to spool the turbo properly. You wouldn't happen to have a wideband would you?
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Old 04-28-2013, 09:55 PM   #3
RodThe3inchKiller
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Default

thank you for the help. ill try disconnecting the vacuum lines to the actuator and see what happens ....i'm kind of confused tho if i disconnected it and there is not enough tension, wouldnt it give me low boost because the waste gate is not closed all the way?

what should AFRL be running at? What are the possible causes for running rich? I dont have a wide band 02 sensor just the two stock 02 sensors. So if its running rich that would also indicate that i have no pre turbo intake leaks. reason being that any unmetered air would make it run lean....hmmm Also my CEL is on for Evap system (small leak) but no others. I feel like that is an unrelated issue but im not 100%

Last edited by RodThe3inchKiller; 04-28-2013 at 10:06 PM.
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Old 04-29-2013, 03:27 AM   #4
mod maniac
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Egg roll is right air psi opens the wastegate and that is the first test I would do. It also sounds like you are running on wastegate pressure are you sure the pill is in the line? Your afr's should be at 14.7 when not in boost and go up to a max of 10.5 to 11.something depending on the tuner. Im not sure what cobb does.
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Old 04-29-2013, 04:53 AM   #5
missmysubie
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this is gonna sound weird but my bugeye had a similar issue. I brought it to the tuner and through the Cobb AP noticed that the ECU was not seeing boost. Its been a while but I think it had a zerod out WGD......He had to retune me for a Hallman MBC and everything was right again in the world.
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Old 04-29-2013, 07:58 PM   #6
RodThe3inchKiller
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Default

I tried disconnecting the vacuum line from the actuator. there was no change.
yeah the pill is dolphinately there. i replaced the line it was in and put in back in the correct location.... afr going up from 14.7 to 10.5? isnt that going down.. sorry im pretty green with this stuff
the AP didnt read any boost or was it low? whats a zeroed out WGD? have any more details on what exactly was wrong with your car.
any other ideas. intake gasket leaking under boost maybe?
Any more information is much appreciated. thanks guys
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Old 04-30-2013, 01:08 AM   #7
mod maniac
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Ok if the boost doesn't go up with the vacuum line off the cats are bad or the turbo is bad or you have a boost leak or you have a massive exhaust leak before the turbo.
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Old 04-30-2013, 01:17 AM   #8
rdowner22
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For a second reference, if you don't know if your wastegate is working, you could take the boost line from the wastegate to the boost controller and hook it to a bike pump with a guage and start pumping... If its a stock TD04 you'll see the wastegate door open I'd say maybe 12lbs? not sure on the stock spring rating.

As for leaks before the turbo, when your engine is cold, jack the cars front up and put it on some jacks... take some soapy water in a spray bottle and spray your headers that come from your block, the crosspipe and then the other side of the exhaust manifold as well as where the uppipe connects. Then go to the top and spray where the uppipe connects to the bottom side of the turbo. Start the car and look for bubbles... spray spray spray... look some more. You kind of have a short period of time before the manifold gets so hot that the water just burns off right when it hits it. But if you find a leak tighten it up more. GL
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Old 04-30-2013, 09:26 AM   #9
prescottn6ft7
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Check the MAF too. Just helped someone local with all the same symptoms as you have and we ended up finding a used MAF from a forester from a local for $20 and fixed his low boost issue.
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