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vt shuddering problem - plugs? leads? coil pack? help please..

Discussion in 'VT - VX Holden Commodore (1997 - 2002)' started by CV6Z, Aug 23, 2010.

  1. CV6Z

    CV6Z New Member

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    been having problems with my car shuddering while driving on the highway and around town. it seems to lose power or has lack of power to even pick up speed...

    its like having wet spark plugs, struggles to coast, you can feel the car shudder bad when goin uphill ect..

    its got a new fuel pump as the old one gave up...could it be a pump problem? it too iseems to be playing up when the fuel gets to under a 1/4 of a tank it stalls...gotta pull over n start the car again.....

    should i just send it to holden to look at and service??

    thoughts?
     
  2. Gokz777

    Gokz777 New Member

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    Have the spark plugs, connectors and coil pack, alternator and battery checked by an auto electrician or use a multimetre. Also check the temperature of your car, check thats its not running cold, or that its an overheating problem. A major service should be done every 50,000km. Worst case scenario you have a busted head gasket and pressure is building up in the engine. Try bleeding out any air. In that case don't waste over $1000 on getting it replaced, go to repco or supercheap, etc. and buy head gasket sealent/repair fluid, costs $10-$15 bucks.
     
  3. V8Silverfox

    V8Silverfox New Member

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    blocked catalytic converter?
     
  4. Tsunamix

    Tsunamix Active Member

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    Ive run into this problem myself. First thing you need to do - Go to supercheap and get a can of aerostart or start-ya-bastard.

    What your doing is looking for vaccum leaks. WIth the engine at idle (max vacuum) carefully spray around these components, listening to hear if the engine revs up. Be careful, this stuff is flammable, and contains a high percentage of ether. Only need to spray a little bit.

    Spray -
    Seal between upper and lower intake manifold.
    Seal around top of plenum.
    Seal around IAC and Throttle position sensor
    Back of plenum where vac hoses attach.
    Back of left rear head where the vacuum distribution block sits.
    Brake booster especially where the vac lines attach.
    Vac hose under the throttle body - one goes to front right of intake manifold, the other goes to the back left head to the vac distribution block.
    Joins between Throttle body and maf hoseing, and maf hoseing and maf.

    No Rev ups ? Ok step 2.
    pull all the spark plugs. Play close attention to the plug that comes out of #6 (closest to driver) if that plug is heavily oiled, replace the PCV.
    Look for signs of lean burning - a whitish residue, powdery. Lean suggests blockage in fuel systems, though it is NOT definitive.
    Replace plugs if necessary.
    Remove and inspect plug leads, looking for signs of arcing. The rubber will burn under arcs, leavving a bluey ehite powder on the heat shields. Replace if any doubt.
    At this point, replace the Coolant temperature sensor. It sits under the thermostat housing in the gooseneck at the top front of the block. It's cheap, $25 and can the source of a few hard to diagnosis problems.
    Inspect your Coil packs. Look for cracking or heat ageing. replace if in any doubt. These are not so cheap. When a coil pack goes, they can often take the DFI out that they sit on. This unit basically triggers the coilpack to discharge, providing spark to the cylinders. If you lift of the coil packs, you may see heat ageing or discolorouration on the DFI contact plate. If you do, replace it. Burtons will sell you a set of coils and a DFI for $300.00

    Still no resolution ?
    next thing on the list is the cam angle sensor and the fuel systeem. The CAS has input on when the Coils fire, so your 'timing' can drift if it misbehaves. On the fuel side, check and replace your fuel filter, Clean the injectors (drop them off and check that the baskets in the end arent full of crap, and that all the seals are intact, rinse them in clean fuel, then rinse them in method and let dry. be sure to use re-assembly lube on the seals when re-assembling, stuffing these seals is a sure vacuum problem.), and also replace the fuel pressure regulator while the plenums off. It sits on the end of the fuel rail, and the regulator is held in by an internal circlip, on the broad face.

    Next on the list is the complex stuff. The PCM - $88 from a wrcker - VT2 is only compatible with VT2 with same gearbox. With the pCM out (the passenger footwell) ensure that you don't have a water leak from the windscreen - dirt trails will be evident. The PCM will need a Tech with an OGBD scan tool to make the PCM talk to the BCM. it wont run without it.

    Still no worky ? Welcome to my world.

    This is exactly the same series of events i got with My VT2 and I've got to the point where it very very rarely hesitates, and only stalls because i have deliberatley retarded timing at idle (oversize Throttlebody gives big torque response when cracking the throttle).

    Good luck - and if you find something that works please let me know.

    Cheers
     
    family fix it man likes this.
  5. Tsunamix

    Tsunamix Active Member

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    Oh dont assume that going to holden or a dealer will get it fixed. Not every device has a 'fault' code associated with it. In addition, if the PCM is misbeahiving, it may not record the fault codes anyway. Your best bet is an experienced auto electrician with a full engine diagnostic centre.

    Cheers
     
  6. IBLOWN

    IBLOWN Well-Known Member

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    Cracked coil pack.

    Go to the wreckers and buy the coilpacks with the DFI module and just replace the lot.
     
  7. pablo

    pablo Donating member

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    Sounds to me like a dud plug lead, coil pack or spark plug,.............. in that order.
     
  8. bricat

    bricat New Member

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    Sounds like leaking vacum hose Check back of engine passenger side I think and under air intake. Usually fall off for some reason. Happened to daughters' car. Same symptoms, cheers Brian
     
  9. Alllife

    Alllife New Member

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    I replaced the sparkplugs and leads to a "performance" sets, and it stopped it completely. Also check if the leads are properly connected, noticed mine weren't and its absolutely gutless and shuddery otherwise
     
  10. johnpro2

    johnpro2 New Member

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    Yes, I agree, my VT commodore used to shudder badly under power & loose power when the throttle was applied quickly.
    The mechanic replaced coil pack, modules, spark plugs and leads ($500) ..expensive however it fixed the problem
     
  11. Turtl3

    Turtl3 New Member

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    were there any signs of this before the fuel pump was replaced? i had a car that we swapped a fuel pump on, pinched the oring on the pump when we installed it. car ran like crap and had low fuel pressure, maybe take the pump out and double check its been installed correctly. other than that im leaning towards everyone else...coil pack
     
  12. bloke04

    bloke04 New Member

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    Had a problem with my Vy also. Replaced plugs leads. Still missing under load. Next in line was coil pack, found self test for coil pack. Removed first two leads and started car . Spark was going from contact to contact. Coil ok! One connection had rust build up. Cleaned contact no more problems! ( I hope).
     
  13. neephius

    neephius New Member

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    This is not a reply but a question
    I have no idea where to write a starting question so as this is close to my own problem I will ask here if that's ok.

    I have a VT 1 V6 in reasonable condition except that it started running rough if I take the number 6 spark lead of the coil there is no change in its roughness and there is also no spark coming from the number 6 coil point would this mean I have to replace the coil packs and DFI module? I replaced plugs and leads with all genuine parts.
     
  14. pulling my hair out

    pulling my hair out New Member

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    SNAP I have had the same problem with my VT2 also done all of the above "fixes" with no luck next is that I am going to replace the harmonic balancer and CAS to see if this may solve it! that only leaves knock sensors and O2 sensors to go. If anyone has solved the dreaded 80kmph mystery please let me know
     
  15. CapnCarnage

    CapnCarnage New Member

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    I have a 2003 VY which is doing something very similar... lack of power and when I put the foot down a bit more than usual (not even 50%) it will start to break down, like the timing is being retarded... myself and several mechs cant figure it out. Have done everything we can think of so far. New fuel sender unit and registers 30psi fuel pressure, new O2s, new injectors, new DFI and coil packs, new leads (TopGun MAX300) and spark plugs (BOSCH), new MAF, cleaned TB, new TB gasket, new IAC and TPS, no faults at all.

    Thinking knock sensors, or a stuffed ECU? Any advice?
     
  16. devilly

    devilly Guest

    egr gasket.move hand around it see if it leaking air.
     
  17. Nut Kracker

    Nut Kracker Kamikraze

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    Only 30 psi fuel pressure???
    Should be upwards of 43
    With a 3 bar fuel regulator
    Check for restrictions in the fuel supply. Eg: fuel filter.
    Correct voltage to the fuel pump.
    Also check your fuel regulator
     
  18. pulling my hair out

    pulling my hair out New Member

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    sounds like the same fault as mine! I replaced the O2 sensors last weekend & that hasn't help either, only things I haven't replaced is the ECU, knock sensors, coolent sensor, Crank Angle Sensor, cam angle sensor its got me stuffed
     
  19. CapnCarnage

    CapnCarnage New Member

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    Yep, I think so...

    I'm looking at a tuned ECU from Ebay, and will be picking up a coolant sensor this afternoon and changing it over Easter as it is due for an oil change now anyway. Have read that could be a cause of issues; I think **** it, I have done just about everything else! $20- from Veales I may as well. New genuine leads going on it too.

    I just had it in a mech workshop and he put a scan tool on it, no codes that he could find, fuel pressure goes up to 40psi and settles 30-35psi. Manifold vacuum is in the green of his gauge so not an issue, knock sensors were kicking in when it was shuddering so we thin that the computer is massively retarding the timing at some point of acceleration as it thinks its knocking, yet we cannot figure out how.

    When cruising around my car goes just fine, idles fine, but when rev it in neutral or I have to go up a hill or overtake and put my foot down a bit further, it shudders and backfires etc... if I knock it back to 2nd, it will take off like a rocket.

    Could it be a fuel curve, because I don't usually plant my foot and it has to re-learn fuel settings? FAAAAAAAARRKKKK
     
  20. CapnCarnage

    CapnCarnage New Member

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    Fuel sender unit is brand new, filter (Ryco) new also. New fuel regulator. Mech clamped off the fuel return line to pressureise system, went up to 100psi just fine, so nothing wrong with the pump. It idles much better with more than 50psi of fuel pressure...

    How can pump voltage be checked?
     

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