Code P0507 idle speed control system

Discussion in 'Import Vehicles' started by Todd1967, Jul 6, 2017.

  1. Todd1967

    Todd1967 Newbie

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    Please fill out the following to ask a question.

    MAKE:Nissan
    MODEL:Altima
    YEAR:05
    MILES:205300
    ENGINE:2.5S
    DESCRIBE ISSUE.... idle runs high, I done a smoke check for vacuum leaks, fixed. I have changed the spark plugs, ignition coil packs, crankshaft position sensor, MAF sensor, intake gaskets, valve cover gasket, pcv valve, throttle body gasket, new throttle body and did the relearn procedure about 20x. Did a compression test, everything good there, also a block test for a bad head gasket, that's good no leaks. I'm running out of options, I think my MAF sensor might be bad. I'm not sure what to do next and or check. Your guidance would be much appreciated.
    Thank you.
     

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  2. billr

    billr wrench Staff Member

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    Have you tried blocking the vacuum line to the power-brake booster? What is the hot idle speed now, in neutral with A/C off? If the idle is really higher than I (or the PCM) expect it to be, the first thing to determine is where the extra air is coming in. You block the IAC inlet port to see how that effects the idle speed. No effect? Then block the PCV and brake-booster lines to make sure one of those isn't a big leak. After that, slide a block of wood across the TB opening, if that doesn't kill the engine then you know there has to be a vacuum leak somewhere; you gotta keep checking. Got it? There is only one way the idle can be too high... too much air getting in; and there are only five ways for it to get in (IAC, throttle, PCV, brake, "other"), we need to isolate which path the air is going and focus there.

    Is this an "electronic" throttle system? I hope not, the possibilities get more complicated if the problem is in the IAC/TB assembly.
     
  3. Todd1967

    Todd1967 Newbie

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    Yes this is a electronic throttle body. With no load it goes from 900 to 1400 then to 1800 rpm. Once i turn on the ac it levels out at about 1000 rpm. The car drives fine when in drive. I will check all 5 locations for vacuum leaks of what you recommend me doing. I will follow up with the results.
     
  4. kev2

    kev2 wrench

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    4 QR or 6 VQ cylinders?
    there are NO other codes ?
    A leak Anywhere after MAF sensor. PVC is specifically mentioned as a possible leak area.
    You changed MAF - did you clean the TB? Do not use a K&N type filter, use a scanner and compare reading to vehicle tach. see attachment
     

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  5. nickb2

    nickb2 Wrench. I help when I can

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    Read this TSB carefully and follow instructions to a "T", it may apply to you.

    Talks specifically of high idle and presence of P0507 codes.
     

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  6. nickb2

    nickb2 Wrench. I help when I can

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    Also, as Kev mentioned, check the intake air inlet tube for any cracks that may be present under scrutiny of a good light source.

    Of note, I am particularly interested in you doing a "manual" idle reduce procedure as listed in the TSB in above post. Seems this would be a good thing to do since the TB was replaced, as also many other major idle related parts/gaskets were also.
     
  7. Todd1967

    Todd1967 Newbie

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    Ok thank you. I will get this going, I appreciate all the help.
     

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