Results 1 to 6 of 6

Thread: Was boosting 11-12psi / now only 8-9psi

  1. #1
    Forum User Feedback Score 0 SuperFast3000GT's Avatar
    Join Date
    Nov 2010
    Owner Since
    2009

    Location
    Nashville, TN
    Posts
    20
    Thanks
    1
    Thanked 1 Time in 1 Post

    Was boosting 11-12psi / now only 8-9psi

    I have a electronic boost controller and a actual boost gauge in the car. (Stock 9b's. Vac reduction/block off plates)

    It's set to-

    start boost 9psi (when wastegates are supposed to start opening)
    Gain 38% (how fast the wastegates open)
    Target boost set to 12 psi

    Before I was holding in the 10-11psi range steady and spiking in the high 12's-low 13's.

    I walked into a store last week and when I came back out and ever since I'm now only holding 7-9psi with the same settings and spiking no more than 10.5 and that 10.5 usually only happens on the first or second boost of my cruise. I made it boost a little higher by cranking up the boost setting to 13-13.5 but it backfired afterward. (running to rich?)

    So, I just bought a 3sx pressure tester. When using a 12v tire pump I found a couple small leaks and fixed them (all i could find with such low pressure-biss screw/vaccum cap where the clutch booster was/BOV... and had already replaced my rear turbos intercooler pipe o-ring) but I'm still having the same issue. The tire compressor won't build any decent amount of pressure to do a real test so I need to get my hands on more air power, I know.

    Until then, anyone have any ideas? Bad boost controller solenoid? Wastegates not sealing right? Or just a random boost leak that suddenly opened up?

    I wouldn't think a turbo went bad. The car still doesn't smoke at all (rare for a 3/S) nor is there oil in my intercooler pipes. Also, the turbos sound fine...there's no whining sound or anything weird or different.

    Someone, please tell me a boost leak could cause my car to still be able to hold a pressure that's steady because that's exactly what it does....it's just less now.

  2. #2
    Forum User Feedback Score 0
    Join Date
    Sep 2010
    Owner Since
    2002

    Location
    Taichung, Taiwan
    Posts
    335
    Thanks
    59
    Thanked 19 Times in 12 Posts
    I would get a MBC and call it a day. A friend with a EBC had a similar problem. It wouldnt boost past 14.7lbs. He switched in a MBC and hasnt had a problem yet boost 18lbs. From what Ive been, EBCs are pretty unreliable.

  3. #3
    Forum User Feedback Score 0 SuperFast3000GT's Avatar
    Join Date
    Nov 2010
    Owner Since
    2009

    Location
    Nashville, TN
    Posts
    20
    Thanks
    1
    Thanked 1 Time in 1 Post
    --------------------------------------------------------------------------------

    FYI- Before I went to into the store, everything was fine and the car was boosting fully according to my settings. I was probably indeed "raising some hell" though, just prior. (but no more than usual)

    I usually sit and let my car idle and cool down before shutting it off but on this day, I was in a hurry. I was in the store for no more than 10-15 minutes. When I came back out, that's when the boost issue had started.

    My electronic boost controller has a built in turbo timer but I haven't hooked it up yet due to being lazy and feeling like I don't need it. I just usually use good judgement and don't boost a lot when I know I am not far from my destination. If I do boost hard and come to a stop, I usually let the car continue to cool down a minute or two before shutting it off.

    On this day I didn't, I just waited 20-30 seconds and went in the store. But, I did come back out and restart it not long afterward. (which is why I thought it would be ok)

    Could that have caused this issue? Oil sludging in the turbo or whatever happens?


    Something in the back of my mind said, "sit, and let this bitch cool before you go in" LOL but I didn't.... and now this. Just a coincidence?

  4. #4
    Forum User Feedback Score 0 SuperFast3000GT's Avatar
    Join Date
    Nov 2010
    Owner Since
    2009

    Location
    Nashville, TN
    Posts
    20
    Thanks
    1
    Thanked 1 Time in 1 Post
    Quote Originally Posted by VR-4 0wnz j00 View Post
    I would get a MBC and call it a day. A friend with a EBC had a similar problem. It wouldnt boost past 14.7lbs. He switched in a MBC and hasnt had a problem yet boost 18lbs. From what Ive been, EBCs are pretty unreliable.
    thanks for the reply! Did he change the settings any? I can raise the actual boost I'm getting up by raising the boost setting or increasing the gain on the controller... but under the normal settings that I have been using for a while... it's not the same anymore.

  5. #5
    Spun Bearing Club '10 Feedback Score 0 O_ROD's Avatar
    Join Date
    Sep 2010
    Owner Since
    2007

    Location
    Ontario, Canada
    Posts
    34
    Thanks
    3
    Thanked 1 Time in 1 Post
    Sounds like a boost leak to me. Find someone with a compressor and pressure test up to around 15psi. Make sure to disconnect and block your PVC return line when doing so.

    After you get that out of the way, if the problem still persists, we can look at other things.

  6. #6
    Here for the party Not Verified Feedback Score 1 (100%) CoreyB's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Location
    Canaan NH
    Posts
    1,749
    Thanks
    368
    Thanked 108 Times in 89 Posts
    Quote Originally Posted by steve68 View Post
    A leak in the exhaust could do it. Like the rear manifold warped, as they all do eventually.

    Steve
    Or a cracked front manifold which is super common as well.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
The 3000GT/Stealth/GTO Web History Project
3000gt.com
3000GT / Stealth International WWWboard Archive
Jim's (RED3KGT) Reststop
3000GT/Stealth/GTO Information and Resources
Team 3S
3000GT / Stealth / GTO Information
daveblack.net
3000GT/Stealth/GTO Clubs and Groups
Michigan 3S
MInnesota 3S
Wisconsin 3S
Iowa, Nebraska, Kansas 3S
North California 3000GT/Stealth
United Society of 3S Owners
3000GT/Stealth/GTO Forums
3000GT/Stealth International
3000GT/Stealth/GTO Event Pages
3S National Gathering
East Coast Gathering
Upper Mid-West Gathering
Blue Ridge Gathering