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Old 06-08-2014, 08:28 PM   #1
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Default Turbo boosting 2psi only, stumped.

I feel I can get better/faster information here than on m.net.

Little backstory. Car is a '92 Black and Tan. Has a Greddy kit on it.
I bought the car about 2 months ago, it had been hit by a deer and when I went to check it out it did not start. I looked it over and found a blown main fuse. Talked him down a bit, came back, replaced the fuse and the car started right up, with some blue smoke of course.

I get the car home, find out there are a lot of things wrong/jerry rigged/lazily done.
-Sebring Timing Box crimped into the CAS wires
-Vortech FMU
-Heater hose used for oil drain.
-A/C lines cut
-Heater core brass lines cut
-CLT wiring fucked
-Massive exhaust leak
-Nasty bad old gas
-Mold inside car
-Top torn

Plus a lot of other little things.

I basically tore the car down, check keyway, timing, wp, etc etc. Pulled exhaust manifold, turbo, downpipe off the car. I did not get the surfaces milled flat. I did take an emery cloth and worked on each surface. Then I installed brand new hardware, new gaskets, and torqued them down till I couldn't anymore. Go ahead and flame me on that one, I don't care. This car will not see more than 5-6psi. I am not building this car, I am simply trying to get it running right.

I have fixed everything. The only thing that eludes me now, is the turbo is not boosting past 1-2psi.
-I have checked wastegate operation. It starts moving around 5psi and is fully extended around 12psi.
-I have eliminated my intercooler as to remove possible leaks.
-I have installed a WBo2 that is now working correctly.
-The FMU is doing it's job, at the 2psi I am seeing it is running 10.5-11.5 afr (not the greatest, but not dangerous)
-I have no exhaust leaks
-I cut reliefs in the exhaust manifold between 1-2 and 3-4.
-I have adjusted the preload on the actuator both ways with no change
-I have unhooked the vacuum going from the compressor outlet to the wastegate actuator and wired the wastegate closed, no change.
-I have removed my BOV to eliminate possible leaks, no change.
-The turbo itself has little side to side play and no in/out play


The only thing I have not done is pressure test my charge pipes. With that I have a question though. If I have my boost gauge spliced into the vacuum line coming from the compressor outlet to the wastegate, if I had a leak in my charge piping, would the pressure I see at the boost gauge reflect that? Basically I'm asking, going with the flow of air, if I had a boost leak, would the pressure be the same in the entire routing of the charge piping, or would the pressure be higher the closer you got to the compressor outlet?

Thanks for any help guys.
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Old 06-08-2014, 08:38 PM   #2
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Pressure is the same in all of the charge piping, basically. The difference will not be large enough for you to accurately measure with a standard boost gauge. 2psi is either a wastegate flapper that isn't closed or a big boost leak.
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Old 06-08-2014, 08:42 PM   #3
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I read 10% of what you wrote, mainly your checklist, didn't see what are you using to check boost pressure? Is the gauge accurate? Is the line connected and not crimped somewhere? If the dude hit a dear maybe the impact pushed something against the vac line. To only make 2psi you have to have a pretty big leak if it isn't the gauge...
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Old 06-08-2014, 08:46 PM   #4
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When I had the gauge tee'd off the intake manifold, at idle it read right around -20 in vacuum, so I am guessing it is pretty close. The gauge goes all the way to max when outside pressure is applied, so I don't think it's crimped anywhere.
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Old 06-08-2014, 08:56 PM   #5
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What would a pretty big boost leak sound like? I need to get a pvc cap and put a valve stem in it so I can test my piping for leaks. That' the only thing I haven't done.
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Old 06-08-2014, 08:57 PM   #6
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I would blame your turbo. If youvd simplified your charge pipes to only a few couplers to run without an inter cooler, I'm guessing you would have found a leak big enough to only create 2psi. Does the turbo spin freely by hand? Does it spin for a minute after shutting down the engine from an idle?
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Old 06-08-2014, 09:01 PM   #7
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Oh god, comparing a video of my car to a car with a boost leak, that's what I have. It sounds too similar. Guess Lowe's will be seeing me tomorrow.
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Old 06-08-2014, 09:04 PM   #8
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I still have about 5 couplers. I'm pretty sure listening to this

and then my car (try to ignore the intake induction sound, I have the hood off)
Video - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting

It has to be a boost leak.
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Old 06-08-2014, 09:06 PM   #9
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Check to see if your compressor housing is firmly attached.... -.-
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Old 06-08-2014, 09:10 PM   #10
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Turbo spins freely by hand, spins for a bit after idling for a minute.
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Old 06-08-2014, 09:11 PM   #11
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The vband? That is tight. There are large c-clips that hold them in place as well. I actually tried to clock the turbo and found that out.
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Old 06-09-2014, 01:58 PM   #12
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You made no mention of exhaust. If everything else checks out and you don't have any exh manifold or major boost leaks it sounds like your cat is stopped up.
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Old 06-09-2014, 03:01 PM   #13
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Kinda sounds like its detonating
either that or you were driving through some gravel
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Old 06-09-2014, 03:03 PM   #14
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Wait. Are you still running the bandaids and stuff you mention in the first post?

When you mention them as being "rigged," what have you changed to fix them?
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Old 06-09-2014, 03:07 PM   #15
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No but seriously, you're describing almost exactly the issues I had. Make sure your CHRA is firmly secured to both the compressor and turbine housings. especially if you've had them apart for clocking.
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Old 06-10-2014, 12:05 AM   #16
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Only bandaid I have hooked up right now is the FMU. I took the Sebring box out completely. Everything was split off of one vacuum port, so I spread them out. No more than two things per port now.

Will a clogged cat cause the car not to boost? I have not checked the exhaust yet.

The pinging sounds were my shift **** rattling around.

I didn't actually have the turbo apart. The only thing I did was take the vband off and tried to separate the exhaust side. When I found out it had large c clips I stopped and put it back on. I had to look up what chra meant :(
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Old 06-10-2014, 12:11 AM   #17
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So you're boosting on a stock ecu with a stock n/a timing map. Yes?
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Old 06-10-2014, 01:49 AM   #18
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At least put the Sebring box back in right and tap on the cat with a hammer to see if it rattles. No joke I picked up 8 psi just by taking out the clogged cat on a 2.3l volvo
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Old 06-10-2014, 11:14 PM   #19
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Yes to stock ECU and stock timing map. So I should hook the Sebring box back up? Thanks for the help so far guys!
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Old 06-11-2014, 02:52 AM   #20
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