Not Cobra related

Bryan Wilson · #1 (**permalink**) 08-31-2008, 09:22 AM

I have a VN V6 work hack that has started running rough. I have changed the plugs and leads with no success could it be the coil pack and how would I go about testing it. From the look of the centre plug on the passenger side it looks like it has not been firring as it looks wet and smells of petrol. All the other plugs are a nice biscuit brown and look like a properly firring plug should. Any help would be appreciated.
Cheers,
Bryan

Rob. Smith · #2 (**permalink**) 08-31-2008, 09:58 AM

G'day Bryan,
Here's my 2 bobs worth...I'm not sure about holdens and v6 setups but if they have individual spark plug wires . Have the engine running,idle is good enough, and pull the plug leads off one at a time and listen to the idle "tune".. If the engine runs rougher while that plug is disconnected. That plug must be OK. If the idle "tune" doesn't change You have found the problem cylinder and plug.
Obviously you have found the suspect plug already so try to "jump-short" the crook plug lead. I mean you should put the offending plug lead. Close to..but not touching, an earth and see if you get a spark. if you do get a spark you've got a dud plug. If you don't get a spark...The lead could be crook. Swap a couple of leads around and test again. If that doesn't work you've got a crook coil. (Here I'm guessing. Is there individual coil packs... one of those could be the problem).
Only a suggestion. Not questioning anybodys' auto electrical / mechanical knowlege.
Good luck,
Rob Smith

boxhead · #3 (**permalink**) 08-31-2008, 07:29 PM

Very common for leads to fail on the V6 commonwhore motors.
If a coil fails it generally takes out the 2 plugs that fire from the same coil.

The VN should have the large one piece coil pack with 2 plug leads coming from one coil.

Doubledip · #4 (**permalink**) 09-01-2008, 03:34 AM

Can also be leaking injectors. lift the rail up after undoing the 4 bolts and switch the ignition on to prime the fuel pump/rail and look at that corresponding injector to see if fuel is pooling. Also it maybe worth your while to invest in a spark checker and then test each plug lead etc... (this device makes the coil push extra hard to jump the big gap and is simple to use) - should be able to pick one up from any decent auto shop.

acecob · #5 (**permalink**) 09-01-2008, 05:53 AM

Rather than playing with high voltage leads try taking the wire plug off the injector on that cylinder you can even go through each one at a time to see the variation on each Cyl. when you find a cyl that isn't working pull off the lead and check it with an ohm meter. If the leads are ok give it a quick compression test maybe it's dropped a cyl. if they are ok it could be your coil pack,

It also sounds Like it could have a vacuum leak around that Cyl check that all your vacuum hoses are on as well

If all that fails Drop a ford engine in it should solve ur prob

serious about the first bit though

sideshow · #6 (**permalink**) 09-01-2008, 11:11 PM

why not jsut sen dit up to my shop

i can fit an l98 into it

no more miss

Bryan Wilson · #7 (**permalink**) 11-12-2008, 04:51 AM

replaced the coil pack and everything is ok now

Cheers,
Bryan