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Compression test results

Discussion in 'Technical Chat' started by brich85, Jul 24, 2014.

  1. Jul 24, 2014 at 2:08 PM
    #1
    brich85

    brich85 [OP] Member

    Joined:
    Jul 24, 2014
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    #134606
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    7
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    Male
    Orange County, CA
    Vehicle:
    1999 Taco 2.7L
    I have a 1999 2.7L with 165,000 miles. Its throwing a p0300 and p0302 code (random misfire and misfire #2). The engine runs fine other than a little shaking when idling, which has been there since i bought the truck in 2007. So far i ran seafoam through the fuel tank and intake, cleaned the MAF, changed the plugs, wires, and swapped the coils to see if the misfire switched cylinders. No change. So i listened to the injectors with a stethoscope and they all sound good. Then I did a compression test and cylinders #1&2 were at 85psi, while #3&4 were at 210psi. According to my Haynes manual the max is supposed to be 178psi i believe. I did a wet test and 1&2 went to 95 and 100 respectively. My next step is to have a leak down test done, however i was wondering if anyone knew of anything else to do before the leak down test (trying to save money on the fix). I'm guessing its a head gasket due to the front two cylinders both being low. This is the first issue ive had with the truck; no noticeable miss, no overheating, no coolant loss or any other signs of a blown head gasket...
     
  2. Jul 25, 2014 at 10:16 AM
    #2
    brich85

    brich85 [OP] Member

    Joined:
    Jul 24, 2014
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    Male
    Orange County, CA
    Vehicle:
    1999 Taco 2.7L
    I haven't had a chance to check the valve adjustment yet, but is it possible the unusually high compression on two cylinders and the low compression on the other two could be caused by bad valve adjustment?
     
  3. Jul 25, 2014 at 10:35 AM
    #3
    tan4x4

    tan4x4 Well-Known Member

    Joined:
    Nov 30, 2011
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    #67982
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    Rick
    Folsom, CA
    Vehicle:
    99 Tacoma EC 4x4 2.7L Auto
    Bilsteins, OME 881's, 3-leaf AAL, Detroit TruTrac, Tundra brake swap, Michelin LTX AT2, Tranny skidplate, TC skidplate, CBI rear bumper, TG sliders, UltraGauge, PowerTank, Reverse Camera
    Could be burnt valves in those cylinders, but I'm not sure how to confirm that. Low compression is one symptom.

    Its easy to check the valve clearances, but hard to change them (bucket and shim design).
     
  4. Jul 25, 2014 at 2:20 PM
    #4
    brich85

    brich85 [OP] Member

    Joined:
    Jul 24, 2014
    Member:
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    Male
    Orange County, CA
    Vehicle:
    1999 Taco 2.7L
    yea im going to get the leak down test done on monday.
     
  5. Nov 12, 2014 at 9:50 AM
    #5
    96coma

    96coma Active Member

    Joined:
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    Member:
    #140242
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    Male
    First Name:
    Josh
    New Hampshire
    Vehicle:
    96 5sp tacoma 4x4
    to much to post lol
    just had my compression done for shits and giggles 96 tacoma 2.7 4x4 251,000 miles the results were
    cyl 1: 124
    cyl 2: 124
    cyl 3: 126
    cyl 4: 123
    they told me that was great results for how many miles that are on the truck and between 120-127 was normal specs? is that good results?
     
    Last edited: Nov 12, 2014

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