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Boost issue any ideas?

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Old Jul 7, 2008 | 10:30 PM
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baggedoutmazda's Avatar
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From: bc canada
Boost issue any ideas?

ok quick run down, this a jdm fd, when i got it no mods except for intake filters, i checked compression good all around, if you take off in 1st gear it boosts good, shift to 2nd fast not boosting, let off throttle you hear noise like something unspooling, then step on it & it boosts. since then i have done silicone lines, plugs 9's all around, 8.5 msd wires, removed double throttle, removed coolant from throttle body, new fuel filter & o2 sensor, crappy e-bay full exhaust, aluminum rad, eliminated ast, restrictor pills are still in, still same problem, sorry i don't have a boost pattern, i know last drive i seen 12psi around 4500 rpm, also breaking up at around 4500 & up i think i may have a couple of problems but as usual not alot of time to work on it, any pointer would be great, thanks
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Old Jul 7, 2008 | 10:44 PM
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sbnrx7's Avatar
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Sounds like it could be the charge control valve actuator. How many miles on the car?
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Old Jul 7, 2008 | 11:10 PM
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apeiron
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Pull the 1" hoses that run to the rear (inlet side) of the charge release valve + pressure release valve.

These will look like they are in find condition, but at the very base where they meet the Y pipe, they become very hard and inflexible (the clamps no longer seal off properly).

Those two things are a cheap fix and 1 more thing to rule out.

I was having an issue with my car where it would boost fine in first and second, but in third fourth and fifth, the secondary turbo would sometimes kick in and sometimes it would not.

While you are at it --- look underneath the pressure chamber (the black box) and make sure that your 1 way check valves are in tact.
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Old Jul 8, 2008 | 12:07 AM
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baggedoutmazda's Avatar
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From: bc canada
not sure of actuall milage on engine, appears to have been changed or at least turbo's changed, it's a 92 which should have restrictor pills in lines, this one has restrictors built into hose fittings, car has 175.000km, also forgot to mention vacume is 18-20 at idle warm. as for check valves they all looked good when i did hose job, but not sure how to test them, probably should just replace them anyway, thanks
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Old Jul 8, 2008 | 09:05 AM
  #5  
baggedoutmazda's Avatar
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From: bc canada
this unspooling problem/sound also happens sometimes from 2-3 gear if shifting fast, under boost from previous gear, shift fast no boost until let off throttle unspooling noise then step on it & it boosts again. very curious what the ''unspooling'' noise i may be hearing is.
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Old Jul 8, 2008 | 09:18 AM
  #6  
apeiron
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From: Boulder, CO
My guess is that when the valve opens for the secondary turbo to engage (turbo pre control valve I believe) you have a leak somewhere on the secondary side of the Y pipe and this is causing a pressure drop.

If your system is not pressurizing properly then this will cause a venting noise / possibly a de-spooling sound from the CRV.

Check the hose that is running to the black release valve, it should run to the middle of the Y pipe just below the coupler.

Pull this pipe off and inspect it.

It certainly sounds like you have a leak though
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