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Old 10-09-2012, 09:36 AM   #1
portable_johnny
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Default only 4 pounds of boost!!!

Im getting my head spinning with this issue. im a general automotive tech who hasnt gotten too much experience with turbos simply because not many people around me drive them. anyway...picked up a side job. 2000 rs with 02 wrx swap. i figured i may as well take it on and learn the engine and system because its the swap i want to eventually do in my car...

~so the issues are...sunroof stuck open. (power to relay, power probed the connector and the motor is seized, thats a given) needs a motor.

~no idle. i picked up the car, wouldnt hold idle. put the clutch in and it dies and it had a CEL. took off intercooker, did a good throttle body cleaning and now it idles. high, but idles.

~Only boosts 4 pounds.

The kicker is everything ran fine, boosted 16 pounds and was an awesome car before it got parked for a month. was started once a week and idled, never driven.

so i brought it to work, put the scanner up to it and got p1090, p1093, p1507. which after some research, the tumbler generator valves. took them off cleaned it out (dont think theyre serviceable, but ya never know) put it back together and light still came back.

for all i know, that could be a seperate issue from the boost. going to get the tgv for both sides and do that. but why wont it hold boost. the turbo screams.

did a smoke test on the whole vacuum system. from the brake booster (which had some external cracks, but wasnt leaking.) then again from the air box. which to my understanding, filled the turbo, piping, intercooler right up to the throttle plate. no leaks, so that rules out a possible leak in intercooler. found a disconnected vacuum line down behind the altenator, but didnt fix the issue.

was thinking about the wastegate solenoid. that stupid electrical thing by the airbox. but i dont think that will function anywhere under 10psi and it doesnt go that high.

so i think im down to turbo or wastegate. turbo screams and sounds like how it always sounds. took a pair of pliars and moved the wastegate door and it did have propper movement, but maybe it could be gummed up like how a throttle body works? will the intake runners have anything to do with it?

im just trying to get more opinions, other than my inexperienced opinion to try to figure it out. remember the car sat for a month and ran fine when it was parked....

Thank you for your time and efforts.
~Kevin
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Old 10-09-2012, 10:15 AM   #2
KOJAK-02-WRX
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The thing by your airbox is the boost control solenoid and if it is stuck open it could be holding your wastegate open and not allowing the turbo to spool.
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Old 10-09-2012, 10:18 AM   #3
portable_johnny
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but wouldnt you visually see the waste gate pin angled indicating its open? idk i un plugged it and went for a ride and had no change

Last edited by portable_johnny; 10-09-2012 at 10:27 AM.
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Old 10-09-2012, 10:27 AM   #4
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you're correct about boost control system. It can't do anything about the spring in the wastegate, and that should be about 9 psi minimum boost. Forget about the boost control solenoid if you're peaking under 9 psi. There's only two things that can cause a peak under 9 psi... the wastegate actuator is detached or broken, or a large leak somewhere between the compressor output and turbine inlet.

The wastegate usually doesn't get gummed up, it gets too hot for that. For the issue you're having, the wastegate would be stuck open or partially open. The only thing you have to concern yourself with is that it's staying closed. You can wire it shut and if it's still only 4 psi, you know you have another problem (A leak somewhere). If it's higher than 4psi, obviously stop boosting ASAP and figure out the problem with the wastegate. Since you have no boost control when the wastegate is wired shut, you can easily get massive overboost, so be careful with that.

Pre-turbo exhaust leaks usually scream like a banshee on boost, so if that's not what you're hearing, it's probably a really large intake leak, sometimes there will be minimal leaking at idle or cruise, when the system is under vac, but when boost pressure gets going, it pushes stuff apart and there's your leak. So you may not see much testing at atmosphere or spraying carb cleaner around while idling and listening for idle changes to indicate a leak.

Pull off the intake box and take the short accordion hose to Home Depot or Lowes. Find the PVC end cap that fits in there. Buy a tire valve at an auto parts store and drill a hole in the PVC endcap and install the valve there. Put the accordion hose back on and stick the cap in the open end and clamp it in. Pull off all the vac hoses from the turbo inlet and make sure they're capped off. Cap the Bypass valve hose by pulling it off at the intercooler side, since it's a total bitch to get at the other end. Find something that fits in the hose. A golf ball is about the right size. A leak this large could be the bypass valve opening, and you want to be able to check it's outlet, so it's better to pull this side off anyway.

Use a compressor if you have one, or bike pump if you don't to pump up the intake to ~20-25 psi. look for post-turbo leaks with some soapy water on every joint in the intake. hose connections, base of the injectors is a common boost leak, bypass valve gasket and outlet. As best you can on the intake manifold to TGV housing gasket and the gasket on the head side of the TGV housing.

As far as idle moving around, if you don't find a leak, the IACV is a possible source for that. You may have cleaned it out with your "throttle body cleaning," I don't know. Here's a good thread discussing how to extensively clean that valve. You absolutely must have a brand new gasket before you start, the old one is not re-usable.

http://forums.nasioc.com/forums/showthread.php?t=781242

Also MAF is a possible source of issues there. CRC electronics cleaner and spray all up in the MAF to clean it may help some, especially if you have an oiled cotton air filter.

Last edited by Concillian; 10-09-2012 at 11:21 AM.
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Old 10-09-2012, 10:49 AM   #5
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wow hahaha. thank you for your imput. going to try wiring the waste gate closed and seeing where it goes from there. i only pressurized it to 5 pounds because i didnt know about blowing out any seals or anything
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Old 10-09-2012, 11:20 AM   #6
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Quote:
Originally Posted by portable_johnny View Post
I only pressurized it to 5 pounds because i didnt know about blowing out any seals or anything
Well, if you're only holding 4 psi, then you must be leaking by 5 psi if that's your problem...

The only stuff that isn't designed to see 25 psi is off the turbo inlet, where it's always vac. That's why we pull that stuff off and cap them, so everything that sees high pressure is designed to see it.

Also there is a third thing that could cause it, some extensive restriction in the exhaust somewhere.
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Old 10-09-2012, 12:50 PM   #7
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and wat about those codes? think it has anything to do with it? or separate issue
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Old 10-12-2012, 12:33 PM   #8
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i think the tgv codes are putting it into limp mode, but there isnt a low rev limit, any other way to check that?
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Old 10-12-2012, 02:55 PM   #9
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ECU cannot force boost lower than wastegate spring (~9psi.) 4psi max mean it's something other than boost control / limp mode. And limp mode will cap it at 4k RPM.

If TGVs are closed it's a significant restriction, but you should be able to see more than 4psi, especially since the MAP sensor is at the throttle body. It should actually see plenty of pressure upstream of the TGVs if they're closed, flow ends up low, but you should still be seeing plenty of boost.

Last edited by Concillian; 10-12-2012 at 03:28 PM.
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Old 10-12-2012, 04:48 PM   #10
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okay thanks for clearing that up
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Old 10-13-2012, 09:30 AM   #11
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found the problem. some wierd form of limp mode. figured id drive it and wipe out the codes as i was driving it. so i was in second gear, cleared the codes, as soon as the light went out, it shot up to 14lbs of boost and took off until the CEL came back on after 5 seconds or so. so just need another tgv and it should be good. after getting pulled over 53 in 30
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Old 10-13-2012, 12:03 PM   #12
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53 In a 50!? Doesn't beat mine.. I got a ticket for $196 for going 58 in a 55 on a coastal hwy. The judge upheld it. Said I was a habitual speeder
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Old 10-13-2012, 01:01 PM   #13
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I have the TGV motors and sensors for sale.
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Old 03-06-2013, 06:25 PM   #14
04_wrx_beckley_wv
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i know this is a old thread, but i have a 04 wrx, throwing p1093 which is tgv stuck closed, its not boosting either, then if i cycle key and get on it, it will boost till i let off gas then stops boosting till i cycle key again, so the tgv closed will limit your boost, anyways, which side is the 1093 closed side, the drivers side or the pass side, is it the one that looks like tps or the other one.
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Old 03-06-2013, 06:30 PM   #15
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I don't know which code is which side, but the majority of the TGV issues are passenger side that people mess up when doing an uppipe, turbo, and or inlet install.
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Old 03-06-2013, 06:37 PM   #16
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well i did kinda crack the front one on the drivers side that looks like the tps sensor, i didnt think it messed it up, but it could have. i was getting a bolt off and socket hit it and i heard a crunch.
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Old 03-06-2013, 06:43 PM   #17
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Both passenger and driver look the same, but the motor and sensor are on opposite sides. Passenger rear is the same as driver front. The motor is the worm gear. You can always unplug them when they're open and have someone with a Tactrix flash the ECU to remove the codes. A worm drive shouldn't move, but you can jam something into the gears to be sure it doesn't slam shut while under load.
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Old 03-06-2013, 06:51 PM   #18
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i just got my tactrix cable in the mail today, was gonna delete them and fix the codes.
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