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2008 cat w/ low boost

Discussion in 'Peterbilt Forum' started by dustinbrock, May 8, 2015.

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  1. May 8, 2015 #1
    dustinbrock

    dustinbrock Road Train Member

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    Apr 19, 2012
    saskatoon,sk
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    been chasing this for a bit now. I have a 2008 pete 389 with a c15 sdp acert engine, has a delete and should be putting 600 to the ground. problem is its boosting 35 to 40 lbs.

    pressure leak tested and all is well, did a complete engine rebuild with new head. only replaced the high pressure turbo because pete said the low pressure one was fine.

    where could my pressure be going? I don't think peterbilt could properly diagnose a failed ball bearing turbo to save their lived (neither can i) so for all I know maybe they were wrong about the one being good.

    a mechanic said to pinch off wastegate line. I pinched it right closed with no change at all, put back to normal.

    thanks in advance.
     
    dustinbrock, May 8, 2015
    dustinbrock, May 8, 2015
    #1
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  3. May 20, 2015 #2
    RSQ20

    RSQ20 Medium Load Member

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    Jul 11, 2013
    Upper Fraser Valley, BC Canada
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    Where are you tapped in to read the boost??

    Turbo outflow, intercooler (in/out) or intake manifold??

    ... Philip
     
    RSQ20, May 20, 2015
    RSQ20, May 20, 2015
    #2
  4. May 23, 2015 #3
    dustinbrock

    dustinbrock Road Train Member

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    Apr 19, 2012
    saskatoon,sk
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    wherever the factory guage is reading from. I've found multiple bad boost leaks and fixed them, then a engine code popped up for the iva oil pressure solenoid which turned out to be a broken wire. now no engine code again and still just 40 lbs of boost.
     
    dustinbrock, May 23, 2015
    dustinbrock, May 23, 2015
    #3
  5. May 23, 2015 #4
    RustyBolt

    RustyBolt Road Train Member

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    Bement, IL
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    Does that model have a turbo with a waste gate? Betting it does. My 05 C13 has the waste gate. Won't build over 31.5 lbs of boost.
     
    RustyBolt, May 23, 2015
    RustyBolt, May 23, 2015
    #4
  7. May 23, 2015 #5
    dustinbrock

    dustinbrock Road Train Member

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    Apr 19, 2012
    saskatoon,sk
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    it does have a turbo with a wastegate. it's the dual turbo acert engine. I should be building 50lbs easy, maybe more with the tune I've got.
     
    dustinbrock, May 23, 2015
    dustinbrock, May 23, 2015
    #5
  8. May 23, 2015 #6
    RustyBolt

    RustyBolt Road Train Member

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    Bement, IL
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    Your "tune" will in no way change the waste gate setting. It's set from the factory. I guess one could adjust it manually by turning the nut on the threaded rod coming from the actuator. Not sure though. Don't think I would mess with it. Bump it up too much and blow the turbo or blow the head off the engine. LOL
     
    RustyBolt, May 23, 2015
    RustyBolt, May 23, 2015
    #6
  9. May 23, 2015 #7
    RustyBolt

    RustyBolt Road Train Member

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    Bement, IL
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    That it to say ... It is set mechanically. Not by the ECM
     
    RustyBolt, May 23, 2015
    RustyBolt, May 23, 2015
    #7
  10. Mar 27, 2017 #8
    bgxpress2006

    bgxpress2006 Light Load Member

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    May 25, 2013
    Montreal, Quebec
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    Bumping this thread up.... i have an 07 mxs with a tune, normally boost in 60lbs range but now only boosting at 30-35lbs range, thought it was air to air, pressure tested it and its perfect, as it should be its new from November, pressure tested in reverse from air to air back to turbos blocking off air breathers and found a leak at top turbo exit at flange, clamp was wore so put a new one on and everything looked good, left shop and nothing changed stil low boost... just before getting home it felt like problem went away, im starting to think this is a wastegate problem.... anybody have any thoughts
     
    bgxpress2006, Mar 27, 2017
    bgxpress2006, Mar 27, 2017
    #8
  11. Mar 27, 2017 #9
    dustinbrock

    dustinbrock Road Train Member

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    Apr 19, 2012
    saskatoon,sk
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    If it's a wastegate issue then pinching the wastegate line should produce more boost. If you've got low boost then you either have a air leak, weak turbo or fuel issue.

    My issue from this tread was a fuel issue. My fuel pump was actually weak. It would test fine at idle but under load it would die.
     
    dustinbrock, Mar 27, 2017
    dustinbrock, Mar 27, 2017
    #9
    bgxpress2006 Thanks this.
  12. Mar 27, 2017 #10
    John3009

    John3009 Bobtail Member

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    Aug 4, 2016
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    @dustinbrock I have the exact same setup as you. 2008 389 with c15 cat that's been deleted and recently been rebuilt. I'm only getting about 38 pounds of boost every now and then it bumps 40. What kind of pressure are you getting now and how did you fix it? Thanks.
     
    John3009, Mar 27, 2017
    John3009, Mar 27, 2017
    #10
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