VZ sv6 driving likes it's 4cyl. (Check powertrain)

[Mykl]

Hi guys, was after some advice and information.
I have a 2004 VZ SV6 auto. Last couple of months it has been driving pretty crappy. Just feels sluggish and doesn't have its usual power. Feels like I'm driving a 4cyl instead of a 6. The check powertrain message has been popping up on the dash every now and then. But isn't always on.
What's extra strange is after I've driven it a bit it randomly snaps out of its crappy drive and is super responsive and feels like it wants to just go. Drives like a dream. Once car is turned off and back on again it's back to its shitty drive. Struggles uphill like it's a 4 banger.
Just had it serviced and I've just changed the oil again to penrite (didn't trust shitty oil from mechanic). Cars sitting at 215kms

I've been doing research on Google and on here to find what the issue might be. I've been told that it could be o2 sensors. Bad coils. Oil sensor. Or spark plugs.
I told mechanic about it and he said he will run diagnostic on it but no errors came up. But I'm assuming that's got to do with the temperamental "check powertrain" warming coming and going.

If anyone has had something similar or knows what the problem could be it would be greatly appreciated.
I'll take any ideas atm thanks guys

 

[99notout]

How long since you changed coils and plugs? It would be my first choice, sound like a coil or two breaking down.

 

[Mykl]

Thanks for the reply. I haven't changed them and i doubt they've been changed since i got the car at 130k. Sounds like it could be that.
Are they expensive to replace?
Cheaper and easy to do myself or just fork out the $

 

[axemurderer101]

I repaired a vz commodore today with a coil issue, was running rough so plugged our scan tool in but had no error codes (will usually give a missfire code) When it was running rough i just unplugged each coil one by one, each time a good coil was unplugged it got worse but when you unplug the faulty coil there is no difference so this is something you could do when your car is playing up. Replaced the coil and it was all good.

 

[greenacc]

Strange there are no codes. One more thing you can do yourself is just go around the whole engine bay and check the battery terminals are secure and all the wiring plugs you can find are plugged in and not broken.

 

[Mykl]

Ok awesome I might look at doing a mix of both things. I'll report back when I find out more

 

[vr_owner]

hey mate id jump on ebay and get the acdelco plugs and coils cost me about $400 delivered but well worth it