Misfiring Only After 1-2 Weeks of Inactivity

[symean]

I have a Commodore VE II SV6 sedan. After a period of inactivity (like not being started or run at all for 1-2 weeks or more while we're on holiday), sometimes on the first startup I get cylinder misfires...sometimes. Car shakes, I let it idle and rev it a little before turning it off and on again. After that, it's fine. Has happened perhaps 4-5 times over 9 years of ownership. In all but one case the CEL turned off after the second start, only this last time it happened the light stayed on. Got it checked and they could not replicate the issue, and suggested replacing all plugs and coils for $950 may fix it, but also said there were many other things that could be causing it, so it's not guaranteed.

I've also seen lots of stories about this reoccurring after replacing plugs and coils, so I decided to just get the code reset for now along with a general service.

I know better than to ask what could cause misfiring in general, but I am keen to hear from anyone who has had this issue specifically under the same conditions - that is, only after a long period of inactivity?

Cheers

 

[Commo64]

Has the car been scanned using a scan tool? This might give you an indication of what's going on...

 

[RossK]

Our VE did exactly the same for the first 4 years of ownership.
Twice it ended up on a truck back to the dealer.
Both times they said it was showing an injector misfire no 6, but was again running fine.
They could replace it if I wished, but as it was running fine, would not be under warranty.
In the last eight years it hasn't done it again.
Coincidentally, I haven't taken it to that dealer for servicing in the last eight years either as I caught them out not changing the oil or filter.
And people wonder why dealers get a bad rep??

 

[Immortality]

I'd suggest it's probably more likely to be a fuel issue. Run a few bottles of injector cleaner through it.

 

[symean]

Has the car been scanned using a scan tool? This might give you an indication of what's going on...

The mechanic did and they only said it was reporting a misfire, nothing more specific than that. I'll see if they have a record of the code(s) when I pick it up...

EDIT: cylinder misfire on 4 and 5, don't have the actual codes...

 

[symean]

I'd suggest it's probably more likely to be a fuel issue. Run a few bottles of injector cleaner through it.

Will do, can't hurt right

 

[Fu Manchu]

Get the battery health checked. battery world can do that and check the charge system. That eliminates one huge cause for minimal effort.

Away a few weeks, battery drops voltage. Gremlins start.
Also get that injector cleaner in. Maybe some moisture build up.

Take the car for a good run somewhere.

 

[Commo64]

Get the battery health checked. battery world can do that and check the charge system. That eliminates one huge cause for minimal effort.

Away a few weeks, battery drops voltage. Gremlins start.
Also get that injector cleaner in. Maybe some moisture build up.

Take the car for a good run somewhere.

This ^^^^^^^

 

[symean]

Get the battery health checked. battery world can do that and check the charge system. That eliminates one huge cause for minimal effort.

Away a few weeks, battery drops voltage. Gremlins start.
Also get that injector cleaner in. Maybe some moisture build up.

Take the car for a good run somewhere.

Thanks, all three planned for this weekend

 

[Immortality]

I recommend this stuff. It's a big bottle and you only add a small amount so it does many tanks of fuel.

https://moreyoil.co.nz/product/moreys-upper-cyclinder-lubricant-injector-cleaner