Thuddering and vibration in idle and when accelerating

[blackstripes]

hey everyone... my car shakes and thudders whenever i accelerate and is really rough in idle.... i got my fuel pump replaced the other week cause the old one shat itself (N) and the mechanic told me that my baby was down a cylinder or two.. i replaced the spark plugs and ignition leads but it's still pretty rough on idle and thudders and shakes when i accelerate.. especially around 85-100kmh... any ideas as to what is wrong? any suggestions would help thanks heaps..

[Sgt Santa Cruz]

probs coils dude or ignition module (under the coil packs) check for spark on the coil packs (assuming its a v6)

[blackstripes]

yeah i just checked for sparksss... one of them isnt sparking..... ithink its the one connected to the 2nd cylinder... what now? haha

[blackstripes]

yeah its a v6 ecotec sorry

[thewheeldeal com au]

Swap them over and see if its the pack itself or something else. If you swap it and the fault follows the pack then its as simple as a trip to Repco or wherever for a new one. If I recall correctly you need like a 4.5mm spanner or something tiny like that....haha.

[blackstripes]

swap the coils around? sory im not much of a grease monkey.. i only joined this to look at other peoples commodores :P and now i actually have a problem of my own haha

[thewheeldeal com au]

swap the coils around? sory im not much of a grease monkey.. i only joined this to look at other peoples commodores :P and now i actually have a problem of my own haha

OK, drive it to a mechanic...someone on here might be able to recommend someone reputable in your area. Maybe call Repco/Bursons before you go and ask about the price of a coil pack for your motor as a reference to ensure the mechanic is going to rip you off. Genuine will probably cost more too and IMO isn't worth the extra coin.

[blackstripes]

too easy.. do you think thats the reason for the thuddering and vibration?

[thewheeldeal com au]

yep, if you've done leads and plugs and a coil isn't firing then you are probably running on 4/5 cylinders which will make it do that, I'm surprised your mechainc didn't test it any further to find that...

[blackstripes]

yeah well he told me that it wasnt running on the 6 cylinders... but wanted to charge me $150 to look at it to see whats wrong... sounded like a G up so i jus checked it out myself haha.. but yeah ill test the coils tomorrow.. or ask dad to anyways :P

[hako]

Before you go replacing coils etc do a fault code check Checking error codes VR/VS (Revised) then depending on whether you have any fault codes stored I would first double check you have the correct plug leads connected to the right plugs and that they are fully pushed home onto the spark plug and the coil. Make doubly sure they are fully home on the plugs as it's easy to just push them on but they don't go on far enough to make contact.
It may also pay to have a look at the engine whilst it is idling in the dark - look for arcing around the plugs/coils leads. This may give you some clues.

[blackstripes]

yeah ill do that, thanks for that.. anything else you think i should do?

[hako]

yeah ill do that, thanks for that.. anything else you think i should do?

You could try gapping the plugs down to 1.0mm which will allow them to fire at a lower voltage but I wouldn't go to that trouble till you've checked those leads are on correctly and connected to the right plugs.