I have the SHO ghost smh

Discussion in 'Gen 1 & 2 - Engine, Exhaust, Drive Line & AC syste' started by SHOYAY, Jul 20, 2019.

  1. SHOYAY

    SHOYAY SHO Member

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    I just can't figure out the running lean issue with my 92mtx. I've changed (with known good used parts and new) tps, iac, fuel pressure regulator, cam sensor, maf, iat, dis , O2 sensors...and all it wants to do is run lean, constantly getting cel because of it and mileage is crappy, not to mention performance is blah. I have 22hg vac and 35 psi fuel pressure at idle... I'm lost...
     
    Last edited: Jul 20, 2019
  2. zoomlater

    zoomlater SHO Member Supporting Member

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    Have you tried cleaning your MAF or swapping it out for a known good one.
     
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  3. SHOYAY

    SHOYAY SHO Member

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    Yes maf been changed also, forgot to put that in lol
     
  4. SHOdded

    SHOdded SHO Member Supporting Member

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    What codes are you getting? If you have a CEL, there must be codes available to look at.
     
  5. SHOYAY

    SHOYAY SHO Member

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    Codes that keep coming up are 172, 176, 326 (egr system has been deleted)
    And just yesterday for first time got 211 code.
     
  6. luigisho

    luigisho SHO Member

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    vacuum leaking hose or seal?
     
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  7. SHOYAY

    SHOYAY SHO Member

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    Can't find a vac leak and have 22hg at idle
     
  8. BaySHO Performance

    BaySHO Performance SHO Member

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    Car would run rough if there was a vacuum leak. Your O2 sensors might be on the blink. I use the Bosch 13942 from Autozone.
     
  9. NoSlo

    NoSlo GoldMember

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  10. SHOYAY

    SHOYAY SHO Member

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    I just put o2s in a month ago...the boschs
     
  11. SHOYAY

    SHOYAY SHO Member

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    I know sorry, out of ideas and what's possibly wrong, everything's been done that I can think of short of pcm
     
  12. itwonder

    itwonder SHO Member

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    Since you've hit most everything else, perhaps an exhaust system restriction?
     
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  13. SHOYAY

    SHOYAY SHO Member

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    Stupid question but would that do that tho? I do have one muffler(driver's side)that doesn't flow good compared to the other one...it has catless y-pipe and stock cat back
     
  14. NoSlo

    NoSlo GoldMember

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    You didn't mention long ago that you had modified factory emissions control devices on your vehicle.

    Tampering with the exhaust changes the resonant frequency, port velocities and timing, gas scavenging, backpressure vs vacuum during valve overlap, etc, which alters the exhaust gasses left in the cylinder vs intake charge at different RPM.

    [​IMG]

    All those fancy pipes on the top of the engine work in conjunction with the pipes on the other side of the combustion chamber, and a computer, that knows how it is supposed to behave, injecting a particular amount of fuel and measuring the resulting stochiometry needed for catalyst activation.
     
    Last edited: Jul 24, 2019
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  15. SHOYAY

    SHOYAY SHO Member

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    So everyone who put a catless y-pipe on were running a lean afterwards?
    I found a partial problem to the lean running... pulled out new o2s to check them and one of them had the tip totally missing, so ordered a couple more new ones.
     
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  16. SHOMON

    SHOMON 95 MTX Supporting Member

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    I never had good luck with the Bosch 02 sensors in either my ATX or my MTX.
    NTK is the O.E. manufacturer and look identical in size and design as the Motorcraft ones I
    put in last year when I was getting 02 sensor codes. They are $2.00 cheaper than the Bosch
    on Rockauto.
     
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  17. BaySHO Performance

    BaySHO Performance SHO Member

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    YMMV. Never had a problem with the Bosch, 13942 (MTX) or 15716 (ATX). Over the last 19 years, many installs of both on client cars.
     
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  18. itwonder

    itwonder SHO Member

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    You can check exhaust system back pressure with a gauge that taps into the 02 sensor bung. Are your fuel injectors the correct ones? We're running Denso O2 sensors, FWIW.
     
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  19. SHOYAY

    SHOYAY SHO Member

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    Fuel injectors are factory. Haven't had chance to drive it since putting new O2 in, will be driving it Sunday
     
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  20. SHOYAY

    SHOYAY SHO Member

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    Put the new O2 sensors in last week and finally got to drive it yesterday, and still running lean smh.
     

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