Revs temporary hanging at 1300rpm

Discussion in '8-valve' started by mrglee, Oct 7, 2022.

  1. mrglee Forum Member

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    Started doing this now and then but happening most of time now hot or cold engine revs will stick at about 1300rpm for 3-5 seconds when I stop before idling worse if you nearly stall before dipping the clutch will go to nearly 2000rpm can't seem to replicate this when stationary cable and linkage all move smoothly and freely
    Also might be related poor cold start then engine idles but touch the throttle and throbs like it's running on three have to let it idle for about a minute before moving off have changed leads cap and plugs with no improvement no codes show engine performance very good.
    96 GTi agg
     
  2. rubjonny

    rubjonny Administrator Staff Member Admin

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    first thing ideally plug diagnostics in check fault codes and your ecu measuring blocks to make sure all the sensors are working ok.

    top suspect though would be a dirty throttle body on these, makes it hard for the throttle motor to keep the idle steady
     
  3. mrglee Forum Member

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    Don't have proper diagnosits but removed the intake pipe and very dirty in there where the flap seats also a lot of oil round the electrical connection on the throttle body shall give all a good clean.
     
  4. mrglee Forum Member

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    We'll all cleaned out and now revs hang at 1800rpm and stays there unless you tap the throttle a couple of times think it's time to take it somewhere to have it checked over.
     
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    could be the cable sticking? worth a check
     
  6. Tristan

    Tristan Paid Member Paid Member

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    Echo what RubJonny said, I had the same problem and found the cable was starting to fray. I also had a dodgy ISV.
     
  7. mrglee Forum Member

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    Got to work reversed into a parking space and throttle went nuts kept going from idle to 3000rpm and back to idle turned off and restated same problem tried turning off and restated again rev shot up to 4500rpm and stayed there turned it off and left till home time really hard to start still very quick on hard throttle tho had a horrible metallic squeal/dragging sound for a while checked underneath all's where it should be but did finally got two codes that will not clear
    00518 tps signal out of range (g69)
    00530 tps -g88
    Does this mean the tps is faulty or when I cleaned all the crap out the throttle body it now seating different to the point out of range?
     
    Last edited: Oct 12, 2022
  8. rubjonny

    rubjonny Administrator Staff Member Admin

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    right so check the flap, the noise you heard was probably the motor. g88 is the sensor for the stepper motor and g69 sensor for the throttle for them both to be flagged suggests something Very Bad has happened to the throttle or maybe you just have a snapped wire or dirty plug
     
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  9. mrglee Forum Member

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    I think your right removed the plug and put back in and started well both codes have been deleted and not returned on start up will idle as normal but as soon as you touch the throttle idles at 1800rpm.
    The sequel metal dragging sound only happens when moving something is rubbing I assume on the brakes tho overhauled 1500 miles ago new discs and pads all round will investigate this further.
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    ok good news. if you remove the throttle cable from the TB and rev it by hand, does it do the same thing?
     
  11. mrglee Forum Member

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    Sorry forgot to mention that does the same thing with cable removed throttle will not close any further.
     
  12. GVK

    GVK Paid Member Paid Member

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    Sounds like the throttle motor gears are sticking, try finding another TB
     
  13. mrglee Forum Member

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    Every now and then after switching off the ignition I can heard what sounds like a small electric motor running after about 5 seconds it stops can hear it wind down sound comes from dash area /engine bay I suppose it's the tb motor trying to overcome the sticking gears will look for a replacement any manufacturers to avoid or recommendations.
     
  14. rubjonny

    rubjonny Administrator Staff Member Admin

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  15. mrglee Forum Member

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    Just to update problem has now gone now idles beautifully not sure how I fixed it tho battery was disconnected for 2 days and charged after it went flat (interior light left on) cleaned the ht cap up and found the knock sensor connector had fallen to bits (replaced) just got a bit more work to do then mot looking forward to driving it again tho have really enjoyed driving the manta around.
     

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