Boost Fluctuating... Any Ideas? - Subaru WRX Forum
 
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post #1 of 15 Old 10-25-2005, 01:09 AM Thread Starter
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Boost Fluctuating... Any Ideas?

Here's the story, I got an AccessPort last monday and installed it and did not notice a difference. Found out I was only at 9.1 lbs of boost, so figured out the the restricter PIL before the wastegate was missing, making it close early. Got PIL hose in there and I was finally getting the boost that I should. Now, my car will boost, then lose boost for a bit, then it comes back, lose it...etc(you get the point), it is very annoying. I've been checking hoses, changed the bov gasket and no change. I'm thinking the ecu needs to be re-set from only getting 9.1 lbs, but I'm not sure. Any one heard of this? Any more ideas?
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post #2 of 15 Old 10-25-2005, 02:25 PM
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When you say it fluctuates, do you mean sometimes you will hit a certain level, and the next time you drive it it is lower? Or do you mean as you accelerate the boost raises and falls?
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post #3 of 15 Old 10-25-2005, 08:46 PM Thread Starter
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Quote:
Originally Posted by Cosmo
When you say it fluctuates, do you mean sometimes you will hit a certain level, and the next time you drive it it is lower? Or do you mean as you accelerate the boost raises and falls?
As I accelerate, the boost raises and falls, then raises and falls.... I just tried reseting my ecu and nothing changed. It's weird, I can't hear any noise like boost is escaping. What do you think?
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post #4 of 15 Old 10-26-2005, 09:06 AM
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Quote:
Originally Posted by nicksalerno
As I accelerate, the boost raises and falls, then raises and falls.... I just tried reseting my ecu and nothing changed. It's weird, I can't hear any noise like boost is escaping. What do you think?
It will do that some. Your ECU is searching for a certain AFR, and you car runs leaner at certain parts of the RPM range. How much is it changing? Do you have a log you can let us see?
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post #5 of 15 Old 10-27-2005, 01:16 AM Thread Starter
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Quote:
Originally Posted by Cosmo
It will do that some. Your ECU is searching for a certain AFR, and you car runs leaner at certain parts of the RPM range. How much is it changing? Do you have a log you can let us see?
Don't have a log. But this morning I brought my AP to work to read the boost on the way there and I saw mostly 17's and one 18 at peak before it backed off. I know that isn't right, the most I should be getting is around 15.8. Looking at my boost gage, if I'm accelerating at about 4500 rpm and up(not really getting on it), the boost will go up to about 0.1 then back off to about 0.06 then back to 0.1 and down again. A few times I've seen it go to about 0.11-0.12 then back off to 0.06 if I get on it. Tried stage 1 to day and nothing changed, just lower boost. I'm getting lost for ideas....
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post #6 of 15 Old 11-05-2005, 09:33 PM
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What will it sound like if boost pressure is escaping. My turbo makes a small whine but I think that's normal, I just want to be sure since I dont have a boost gauge.

Brent
2007 Satin White STi, 1989 Nissan Sil-Coupe, 1998 Toyota 4runner (to be built..)...
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post #7 of 15 Old 11-06-2005, 01:40 AM
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not to much of a whine but more of a whisle.


all the intercooler hooses are tight and not leaking right?
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post #8 of 15 Old 11-06-2005, 03:09 AM
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i havnt played with the stock boost control setups for a while but shouldnt the pill go in the pipe from the pressure source to the tee not the wastegate side. i think what it does is changes the resolution of the control solenoid. Someone with a stock one check under their bonnet and let us know please. in my 2000 model it was on the comp cover side of the tee not the actuator, i think. have you put a different BOV on, check all connections for vacuum and boost on the manifold.if you have changed anything put it back to standard 1 piece at a time until you find which mod it is, dont bother changing the exhaust after the turbo as it will not cause this, it is either electrical or pneumatic (vacuum pipes, intercooler pipes, BOV) good luck
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post #9 of 15 Old 11-06-2005, 10:32 PM
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I've noticed a nasty surge / fluctuation when I accelerate at 3/4 throttle. If I stand on it, she will hold at about 19 lbs, but at moderate acceleration it wavers between about 8 to 15 lbs. I had my tuner to drive it & check it out and he said that it simply didn't like not having full throttle. He explained it that with the VF34 & big exhaust I was overflowing the exhaust, the engine was searching for more throttle input to keep up with exhaust flow. He also said that it was a common complaint with bigger turbos on auto cars. His solution was just run WFO all the time! Don't know if he was BS'ing me or not, but it made sense since it only does it at moderate acceleration.
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post #10 of 15 Old 11-07-2005, 04:21 AM
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remove your bov and block off the hole, see if it still happens, with this info it sounds like it may begin to open with part throttle. if it does not do it without a bov then simply tighten the bov spring until it stops doing it. pressure on either side of bov piston becomes equal and it opens slightly until pressure bleeds off then closes again causing fluctuating boost at part throttle. this is not normal and any tuner who says otherwise is looking for the easy way out. I'd find another tuner, this guy is lazy and couldn't be bothered looking by the sounds of it. especially if he is the guy who fitted the gear and has given a warranty.
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post #11 of 15 Old 11-09-2005, 07:10 AM
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have you tried putting the intake silencer back in?
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post #12 of 15 Old 11-03-2006, 04:55 AM
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I removed my intake silence and have a BOV and boost gauge All were done withing one day, I am thinking the Silencer is doing the same thing to me on my 07, I just bought it and have a dual stage BOV and mechanical gauge for now, but I removed the silencer after the gauge install and I don't remember it doing it with the silencer in. Could the silencer make my car surge at partial throttle?
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post #13 of 15 Old 11-03-2006, 02:11 PM
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Quote:
Originally Posted by Team Dream
I removed my intake silence and have a BOV and boost gauge All were done withing one day, I am thinking the Silencer is doing the same thing to me on my 07, I just bought it and have a dual stage BOV and mechanical gauge for now, but I removed the silencer after the gauge install and I don't remember it doing it with the silencer in. Could the silencer make my car surge at partial throttle?
no it shouldnt all the silencer does is quiet the intake noise it does not change performance at all in or out. ill look at my stock boost control stile guy what exactly am i looking for and ill let you know.
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post #14 of 15 Old 11-03-2006, 05:18 PM
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I went to the dealer and explained it to one of the reps, he said it sounds like the boost solenoid, so I am bringing them the car Monday, the silencer is back in but the car is running funny, and the boost fluctuates at anything over 1/4 throttle
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post #15 of 15 Old 11-05-2006, 11:48 AM
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i had the same problem on my 02 wrx and like cosmo was saying a dealer tech told me it was the factory boost control soleniod trying to regulate to a certain air/fuel ratio. when the boost would creep up the ECU would tell the solenoid to place a cut on the boost to regulate thus the dimmer switch feeling of acceleration and boost. i placed a greddy profec spec B EBC on my car an OOOO YYYYEEEAAA its 17.5 18.0 PSI constant. i have no cats and a front mount so i think it sould handle it but good luck buddy. man that was annoying though
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