B18C high idle, slight hunt

Discussion in 'Engine' started by Dannyboy205, Jan 17, 2018.


  1. Dannyboy205

    Dannyboy205 Donator Donator

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    I purchased a modified 98 dc2 from my friend and i have put it back to standard but have a few issues.

    The car starts and runs. Bit the idle when warm is around 1250-1500 ticking over and when pulling away and coasting etc the idle can climb to 2.5k and hang around there.

    The car had an aftermarket TB. I replaced the TB and IACV with second hand items.

    So far i have
    Checked the TPS values and adjusted it
    Cleaned out the IACV and checked resistance
    Blocked all vacuum pipes to check for leaks
    Sprayed brake cleaner to try find a vacuum leak
    Adjusted throttle stop and clean TB to get best seal
    Screw the idle screw in as far as possible to see if idle drops

    My next options are, try a 3rd IACV or replace the second hand throttle body. I think the idle screw has been replaced in it and might not give a perfect seal.

    Is there anything obvious im missing?

    Tomorrow ill block of the iacv port again and see if it dies and try narrow down the air supply thats keeping her revving.

    Unless there is a vacuum leak. Surely its an IACV problem? Or the idle screw thats been replaced is not correct
     

  2. irf

    irf Donator Donator

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    How did you clean the throttle body? Did you open the valve and clean around/behind it?

    Block off the iacv as you said but on cold start. If it doesn't die I think you might have cleaned away the throttlebody valve seal.
     
  3. Dannyboy205

    Dannyboy205 Donator Donator

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    I used throttle body cleaner as usual. It is an old throttle body. Im wondering if the butterfly just cant seal well enough!

    If the IACV is blocked of on cold start, it should die shouldnt it. If not i must have an airleak! But i cant find it any where.
     
  4. MotorMo

    MotorMo Active Member

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    That's a fairly large 'leak' for it to idle hunt...I believe the 98 spec DC2 Type R throttle body does not have a 'fast idle valve' that other Integra's have. You stated your using an old throttle body- just a thought to make sure this T.B. doesn't have one.
    upload_2018-1-18_7-47-52.jpeg With Fast idle, VS [​IMG]No fast idle. [​IMG]
     
  5. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    youve either got an air leak or your iacv is getting stuck open. tap it with a hammer whilst running, it may lossen it and allow it to work properly again.
     
  6. Dannyboy205

    Dannyboy205 Donator Donator

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    Right few updates

    I smoke tested the intake, there are no vacuum leaks.

    I ran the car up to temp. When i disconnect the iacv the car idles slightly lower but still above 500 rpm.

    When i blocked of the port in the TB that feeds the IACV and idle screw the car dies.

    Meaning no air is entering around the throttle plate as suggested last night.

    This is a b18c TB, i checked. The previous owner of the TB suggested the idle screw may have a fault. I think this is causing my high idle. If i remove the iacv conpletly from the car and blank it off. Then run the car with the idle screw all the way in. It shouldnt run at all
     
  7. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    ok so it seems youve narrowed it down to the idle screw. its a pretty basic function so i wonder why its letting so much air through?
     
  8. Dannyboy205

    Dannyboy205 Donator Donator

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    Im not sure if its been stripped. Then replaced with the incorrect size. So it never closes fully!
     
  9. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    must have been something like that.
    probably needs a new TB then unless you want to tap a new thread for it
     
  10. Dannyboy205

    Dannyboy205 Donator Donator

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    Ill probly replace the throttle body.

    My next problem is the speedo not working. When i purchased the car it was ok.

    Reads in kmh still

    Ive swapped over another VSS. Ive also replaced the plug with a brand new multi plug and pigtail. And ive removed the multi plug to the speedo and cleaned it. Is there any way the speedo drive has been worn out in the diff itself? Or is this un heard off. I removed the VSS and had a look inside. The sensor should centralise itself.

    Does any 1 know what output signals should come from the vss. I buzzed the plug out quickly and found a 12v feed
     
  11. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    id be very surprised. although i think the gear thats on the diff is pressed on so its possible i guess.
    are you getting voltage at the sensor?
     
  12. Dannyboy205

    Dannyboy205 Donator Donator

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    Ive left the workshop now. Was getting frustrated and hungry

    Im assuming i should have a 12v feed
    A ground
    And a signal to the speedo?
     
  13. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    iirc its 5v.
    yes youll have a reference voltage, ground and and a signal voltage back to ecu. id jack the front end up and let it run in gear. test voltage, change gear and see if voltage changes as wheel speed increases
     
  14. Dannyboy205

    Dannyboy205 Donator Donator

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    Exactly my plan mate. Thanks! I have a lift so ill raise it a foot. I did think all of the sensors where 5v. Im not sure where i got 12 from. I did wonder if it had a dodgey converter wired in some where/ removed. But i havnt come across it yet!

    Trying to get this 98 back to ita glory.

    Already done brakes, Cam belt etc
     
  15. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    its certainly possible. issues like this are always time consuming arent they
     
  16. Dannyboy205

    Dannyboy205 Donator Donator

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    Proped pain! I have dug out the service manual and the test for the VSS is as you said.

    Check for 5v feed. Ground. 5v pulsing from the signal wire.

    Then check wire from ECU to cluster for 5v.

    I have 2 VSS. I have an exploded diagram for the internals. Ill open them up tomorrow and make sure the little join isnt broken

    Screenshot_20180118-212505.png
     
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  17. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    good shout on the drive link within the vss, i didnt think of that
     
  18. ellb123

    ellb123 Member

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    You could also put the VSS sensor into a drill and spin it up, that way you can rule out/in the diff?

    There isn't separate fuse or anything you could have missed either? When my speedo didn't work it was the fuse that uses both the alternator and the speedo
     
  19. Dannyboy205

    Dannyboy205 Donator Donator

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    Well im one step closerm good shout for the fuse! There is one i need to check.

    I removed the replacement VSS. And split both of them.

    Two things i found. The drive link was missing in one, and the gear was smaller on the other!!

    Between the two i have now constructed one good sensor! Havnt had time to run it yet.

    20180119_131237.jpg

    20180119_131329.jpg
     
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  20. jesse888

    jesse888 Ek9+Turbo+Nurburgring= Heaven Staff Member Donator

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    ah so it was the vss then, glad you found it
     
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