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Thread: 1990 G60 Surging Idle On Startup - Corrects with defogger ON

  1. #1

    1990 G60 Surging Idle On Startup - Corrects with defogger ON

    New G60 owner here with an Idle issue I can't seem to find any mention of here.

    The car will rev between 1000 - 2500 RPM a few times when starting (only after the engine warms up, first start of the day is fine) and corrects itself almost immediately after I turn on the windshield defogger. Also worth mentioning the car idles at 1200 RPM constantly on a good day.

    Rarely it'll choke up and stall - although I don't think this issue is related and I haven't been able to replicate it.

    Things I have done:
    - Cleaned ISV
    - Replace Blue Temp Sensor
    - Installed correct Spark Plugs and wire (previous owner had incorrect plugs installed)

    Any clue what's going on?

  2. #2
    CF-oholic! seanl82's Avatar
    Join Date
    1st September 2011
    North Devon
    I'd check all your vac hoses to make sure there are no breaks or splits first, but it could be a battery or alternator issue. The fact that revs change when you switch on the heaters is normal. You're demanding more from the battery, and so the alternator will supply more power to compensate, hence you get the slight drop then surge whenever you turn on any electrical item. The lights are usually most noticeable. 1200 rpm is high though, so unless someone has been fiddling with your idle screw to mask or incorrectly overcome a stalling issue (sounds plausible), I reckon checking vac lines and intake pipework should be your first port of call mate.
    95 Classic Green VR6 - Jetex Cat Back|BMC CDA|VT mounts|Bilstein B12s|288mm front brakes|Mk4 Rears|Braided hoses|Daves16v shortshifter|Lupo wipers|Uprated headlight loom|
    CCGB #3982

  3. #3
    Join Date
    15th October 2008
    West Yorkshire
    Someone has probably messed with it, so you need to do a full service and check over of vac lines / wiring to look for any damage, then set the car up. Start with static timing to make sure it's not a tooth out or anything, then dynamic timing with idle adjustment - if you google it Rubjonny did a guide on this, it's the same as for a 8v gti (PB engine).

    A major culprit for idle issues is the rubber o-ring on the idle screw, so remove this before setting it up to make sure all a'ok

  4. #4
    Thanks guys this is great help.

    I just received 2m of vacuum line from BBM I’ll be swapping in today. Will updates progress here for anyone else who might have the same issue.

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