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Old 01-22-2007, 11:36 AM   #1
rexecutioner
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2002 WRX sedan
silver

Default bad turbo?

Its been a long time since visiting this site, hoping I can get this problem sorted w/minimal time down. The car is a 2002 wrx w/84.5k on it.
I noticed this wkend that my turbo is acting irradically. When I stomp on it and the turbo kicks in, the needle bounces up to 18-20psi and then it drops off, as tho the turbo isnt working. When going a lil softer on the throttle it goes up to about 5-7psi w/o issue but wont go higher, sometimes it stays at this level and others it drops off, as stated above.
I did all of the mods myself so I am somewhat competent in that area. Just need some pointing in the right direction. If it turns out to be a bad turbo I would consider upgrading and making some further mods. If its an ez fix then I would like to fix it at least for the time being while considering my options for making this baby a lil faster.
Right now the car has a turbo xs exhaust and one of the first downpipes that came out, came from the west coast along w/an underdrive pulley, cant remeber the guys name( shiv comes to mind, does that sound right?). I had one of TXS first piggyback chips and boost controler(stage 2 I think) but it was removed at some point because I didnt like the tempermentalness of the car at part throttle. STI hood scoop, split intake so the air doesnt go to the back of the scoop, silencer mod, EGT and fuel pressure guages.
I'm not too sure what improvements have come and gone in the past 3 yrs, I recall the vf34 being the turbo of choice back then. I will do some reading/catching up in the meantime. If anyone could help w/some suggestions for the quick fix it would be greatly apreciated.
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Old 01-22-2007, 01:12 PM   #2
big16gwrx
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if i were you i would check all of the connections from the turbo to the inter cooler, get some t-bolt clamps put them in place of your hose clamps and tighten everything down you can get clamps from pep boys.... also i would check all of your vaccume connections.... you may want to also do a pressure test... there is a thread somewhere that talks about making a pvc fitting and hooking it up to the turbo inlet tube and pressurizeing the system to like 10 psi and listening for leaks.... sounds to me like you got a major leak... possibly even a blowen fitting somewhere... but thats just my .02....
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Old 01-22-2007, 04:40 PM   #3
rexecutioner
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That sounds like the right place to start and a leak did cross my mind. I'm a little doubtful thats the problem because I do show quite a bit of vacum comming off throttle at high RPM. Roughly 26in @3000rpm, I tend to think this wouldnt be the case w/a leak???
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Old 01-22-2007, 10:31 PM   #4
rexecutioner
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OK, did a lil reading in the 2.0 turbo forum. Seems I need to make one of these leak listening decives out of 2" pvc ebow, a cap and a valve mounted thru the cap. I'm guessing I need to take the valve plunger out and hook a hose up to the valve and use it like a stethascope? I still think I would be losing vacum if I had these leaks but I'll try anything to get this figured out. BTW, above I sated I have a shiv downpipe...... that should read uppipe. The exhaust is the turbo xs turbo back.
I am a bit worried about the high boost pressures, is 18 psi a dangerous in a momentary spike?
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Old 01-22-2007, 10:38 PM   #5
hondaeater69
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drops off to what PSI? if it drops to like 15 or so, or you have boost hunting (where the boost doesn't settle) you are overboosting/spiking and your ECU is having a hard time controlling boost. you need a tune.
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Old 01-23-2007, 09:15 AM   #6
big16gwrx
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your right could be boost spike.. cold weather can wreak havoc!
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Old 01-23-2007, 05:03 PM   #7
rexecutioner
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Thanks for the input HE69, for the most part it dropped down to 4, sometimes as low as zero... anywhere in that range.
Today is a different scenario, I dont hear the turbo spooling up at all anymore and the boost doesnt go over 4psi at any time and remains at or just above zero until 4-5K rpm
At idle w/the car warmed up I am still pulling 21 inches of vacum.
Talked to a mechanic today who does aftermarket work only by appointment. Site unseen, he felt it was a wastegate problem.
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Old 01-23-2007, 05:20 PM   #8
hondaeater69
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yes could be WG is too loose, or the turbo is going bad.
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Old 01-28-2007, 05:34 PM   #9
rexecutioner
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To my surprise while on a long drive this wkend the turbo started working again. It works fine so long as you dont mash the pedal. At part throttle I get 5-6psi boost. However, when putting the pedal down the boost spikes up high as before, and then it cuts out completely. It doesnt work for a while after this and then suddenly it comes back. What would cause this boost cutout? It was suggested to me that the culprit could be the boost control valve or a sticking wastegate. How would I go about figuring out which of these is actually the problem?
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Old 01-28-2007, 07:07 PM   #10
hondaeater69
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you may want to start by taking a log of your ecu when this is happening. if you are overboosting, and knocking, your ECU has the ability to pull boost back until the detonation goes away... this may be what you are experiencing.
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Old 01-29-2007, 08:39 PM   #11
rexecutioner
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It was suggested to me today to try reinstalling the manual boost control that came w/the TurboXS stage 2 unichip combo that I shelved 3 yrs ago. It was explained that due to the colder temps the turbo may be flowing more, thereby creating more boost. Does this sound feasble to you? I mean this hasnt happened in past winters.....why now?
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Old 01-29-2007, 08:41 PM   #12
rexecutioner
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PS. I dont have the means to do the ecu logging, guess I have to do some more reading and decide whether I should invest or just bring it to someone who is capable.
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Old 01-29-2007, 11:47 PM   #13
rexecutioner
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I think what I am getting is fuel cut when the boost spikes to 18-20psi. I get a sudden loss of power, 0 boost, and even a change in the exhaust note for a time..... then all of a sudden I get boost back 15 min down the highway along w/an improved exhaust note. Would a faulty FBC be causing this? BTW, is the factory boost control and a boost control valve the same? Or is the valve that plastic restrictor or pill in the line to the BCS? I am thinking the BCS is the culprit from some things said in that wastegate arm thread.
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