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Thread: VR6 Sounds Like a Lumpy Tractor

  1. #1
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    VR6 Sounds Like a Lumpy Tractor

    1993 OD1 VR6

    Hey guys, so went to use the VR the other day to discover a flat battery.

    Jumped the car and got it running, but unlike normal it sounds terrible.

    Sounds like it has cams in it!!

    Feels extremely lumpy!

    Idle is stable on the Rev counter at 1k cold start and 750 warm, but sounds like a chugging or misfire, exhaust farting etc.

    Engine movement is present on idle.

    On the road it seems to pull okay maybe a little flat but with no signs of misfire/kangarooing.

    MAF has been unplugged with a noticeable change so I think that can be ruled out.

    Checked and changed the plugs, top bank looked fine bottom bank were oily.

    Leads/dizzy and rotor arm were changed a year ago.




    Anyone with suggestions Please

    Thanks

  2. #2
    CF-oholic! fla's Avatar
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    Might be a blocked injector. Post up some pics of the spark plugs - this can tell a lot
    Hasan
    VR6 Auto to manual conversion, beige leather, aircon, TT comps, blue dash lights & switches, Koni TA/Nothelle springs, OBD2, 264 cams, Schrick

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  3. #3
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    Unfortunately I threw them away however after changing the plugs it seemed to run okay, that was yesterday now it's back again.

    The car seems fine when driving just not so great when at idle.

  4. #4
    Enthusiast Gti_Jamo's Avatar
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    Have you checked the voltage at the battery? Since it was flat it could be not charging properly and the ecu is not getting 12v on idle.
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  5. #5
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    Interesting!
    I did check the voltage at the battery when it wouldn't start and it read around 10.5v

    I shall indeed re-check the voltage shortly.

  6. #6
    The ECU will likely have lost adaptation to your engine if it has lost power from the battery.

    Now usually, in my experience, this results in the car running smoother for a while as it will tend towards overfuelling until it adapts again but you may find issues if it's not had a clean power loss and re-apply so I would suggest doing the ECU reset process in a controlled way. That just means disconnect the battery fully for 30 seconds before reconnection. And of course you want the battery fully charged when you do this.

    Car power supply is very messy, the ECU should tolerate voltage drops as low as 8v during cranking, but if you have a flat that can't start the car at all it's possible this can cause issues for the ECU too.

    A Corrado is for life, not just for the MOT.
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  7. #7
    CF-oholic! fla's Avatar
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    Then take it for a good drive for at least half an hour at motorway speeds. When the temps are up to normal do some hard acceleration in 2nd and 3rd.
    Hasan
    VR6 Auto to manual conversion, beige leather, aircon, TT comps, blue dash lights & switches, Koni TA/Nothelle springs, OBD2, 264 cams, Schrick

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  8. #8
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    Hi,

    Okay so re-checked the battery and the voltage is all good.
    I decided to disconnect over night to see if it presented any remedy, unfortunately not.

    Had a spare blue coolant sensor knocking about so decided to fit that.
    Measured the pins on the current sensor and it seemed off so replaced it.
    Car is still running lumpy on idle.
    I put a cone filter on the car prior to the idle issue and all was fine but decided to re-fit the factory air box incase that was affecting the MAF, still no good.

    So to recap:
    Fresh Plugs
    Dizzy
    Rotor Arm
    Blue Coolant Switch
    MAF okay

    Engine fires immediately
    No noticeable power loss when at WOT

    RPM fluctuate slightly at idle

    Car sounds like it's chocking at idle

    At low speed and accelerating it sounds like there is resistance from the engine but above 2000rpm it pulls nicely.

    Can I achieve anything plugging in via the ODB1 ports?

    Could the ISV be causing these issues potentially.

    Much appreciated for all responses.

  9. #9
    The ECU will tell you if there is a fault, yes. That's always worth doing. Yours is a 93 with the OBD2 socket?


    A Corrado is for life, not just for the MOT.
    [ WARNING: the above message may contain irony, sarcasm and outright lies. ]

    ** Every time you think about sex, another Corrado gets written off. **

  10. #10
    CF Nutter fendervg's Avatar
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    Check for any vacuum leaks on the inlet elbow and manifold, and the PCV tubing.
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