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Thread: VZ Commodore running rough

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    Default VZ Commodore running rough

    I have a VZ Commodore 2004.2 months ago had the plugs and coils changed.
    The last few days i's been running rough,like one cylinder is missing,the same symptoms as before I had the coils changed.
    After about 10 mins shaking it goes back to normal all day.
    The mechanic said it's the computer( common fault) with Commodore.
    $ 600.00 to replace and reprogram it.
    Once the engine warms up ,no problem.
    Any ideas?
    Thanks in advance
    Gulliver

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    Quote Originally Posted by gulliver View Post
    I have a VZ Commodore 2004.2 months ago had the plugs and coils changed.
    The last few days i's been running rough,like one cylinder is missing,the same symptoms as before I had the coils changed.
    After about 10 mins shaking it goes back to normal all day.
    The mechanic said it's the computer( common fault) with Commodore.
    $ 600.00 to replace and reprogram it.
    Once the engine warms up ,no problem.
    Any ideas?
    Thanks in advance
    Gulliver
    Hi I would find another mechanic I have never heard of a ECU playing up on a VZ ( assuming its a V6) I would suspect one of the coils has failed again ( I see a lot of GOSS branded coils fail weeks after fitting) what brand coils where they ? Most cars I fix with ECU problems are good when cold and play up when warm.
    I am assuming he did a scan and no codes came up ? .
    and if you wanted a ECU Id buy one from a wreck (cheap) and have a local mechanic program it to the key and BCM for you

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    Its not the ECU, has he had it on a tech2 to diagnose it properly, Did you replace the plug leads? any signs of loss of coolant? I'd be more inclined to say you have dirty dribbling injectors, does the car blow much black smoke on start up and when its running rough

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    I've had similar problems in the past that were caused by the connection TO the coil. It's not necessarily any engine connections (leads) at all.

    IIRC (it was a while ago) it was the ignition connection. The symptoms were as you describe.
    The fact that there's a highway to hell and a stairway to heaven says a lot about the anticipated traffic flow.

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    Quote Originally Posted by carjackma View Post
    Hi I would find another mechanic I have never heard of a ECU playing up on a VZ ( assuming its a V6) I would suspect one of the coils has failed again ( I see a lot of GOSS branded coils fail weeks after fitting) what brand coils where they ? Most cars I fix with ECU problems are good when cold and play up when warm.
    I am assuming he did a scan and no codes came up ? .
    and if you wanted a ECU Id buy one from a wreck (cheap) and have a local mechanic program it to the key and BCM for you
    In 250,000 K our VR has gone through 3 Coil packs. The symptoms were running as rough as HELL. replace them all and the engine was good.

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    Another proble I have and still have it after 23 Years of having the VR and some VZ are the same.
    After you go for a drive and park it for 20minutes to 1 hour and you come back and start the engine it runs as rough to a point that the car stalls one in four times you do this. Once I put the foot on the peddle its ok after this. If I leave the car over 1 hr its ok, if i leave the car over a day, one week, on month is ok. I was getting some one to look at it but I cant trust any Mechanic as I always done repairs myself. I can live with it.
    Last edited by Mr 672A; 21-06-18 at 10:08 AM.

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    In my experience a car that runs rough when cold but fine when warmed up could indicate a bad intake manifold gasket, basically the car is able to suck air in (vacuum leak) when cold but when the car warms up the gasket makes a good seal (no vacuum leak) and runs fine. There are a few ways to test for this 1) Spray some carb clean around the intake (carefully) when the car is running poorly, if the RPM changes when you spray a particular spot it means its sucking in from there. 2) Smoke test - done with a special smoke machine 3) Scantool and look at the fuel trims that can help as well. There are other ways but i would it would take forever to write.

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    Quote Originally Posted by carjackma View Post
    Hi I would find another mechanic I have never heard of a ECU playing up on a VZ ( assuming its a V6) I would suspect one of the coils has failed again ( I see a lot of GOSS branded coils fail weeks after fitting) what brand coils where they ? Most cars I fix with ECU problems are good when cold and play up when warm.
    I am assuming he did a scan and no codes came up ? .
    and if you wanted a ECU Id buy one from a wreck (cheap) and have a local mechanic program it to the key and BCM for you
    Yes it's a V6
    He did a scan and no faults came up.
    That was I was thinking.Exactly the same as with 1 faulty coil before.
    Thanks

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    Yes, I lost some water after a new radiator and thermostat.
    I filled up 1 litre yesterday.

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    Default VZ commodore

    Thanks to all of your posts.I'll check out some of the suggestions.

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    I think vnboost is right.When I had a faulty coil,the fault came on and off,hot or cold and I could smell petrol when running rough.
    Not this time,no black smoke coming out when running rough.
    But I used another 1 litre of water in one week and once the car warms up it will be fine all day,
    have to check out the water loss tomorrow because new radioator and thermostat.
    Thanks again for all your posts.
    Last edited by gulliver; 01-07-18 at 04:17 PM.

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    Any oily goop under radiator cap?

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    Quote Originally Posted by gulliver View Post
    But I used another 1 litre of water in one week and once the car warms up it will be fine all day,
    have to check out the water loss tomorrow because new radioator and thermostat.
    Thanks again for all your posts.
    Loss of coolant could indicate, valley cover gasket, or head gasket or even a cracked cylinder head, Any noticeable steam and excess water from the exhaust when first started?

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    I just had a mate with a customers car here today that was running rough only when overtaking.

    New set of coil packs sorted it out......

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    I know it's an old thread bu keep you updated.
    About 3 weeks ago it was running rough all day.
    New plugs and checked injectorsand pressure test All ok.
    New computer all fixed. It missed number 6.

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