Sputtering 2005 S40

[Dominik]

My brother's N/A 5cyl Volvo sputters just after startup that usually lasts for a minute or so once warm the engine runs smooth. I suggested FI cleaner like RedLine S1 since the car had been sitting for 5-6 months the gas might have been stale but then why would it only sputter at startup? No there are no error codes or check engine light.
Please chime bros' in any suggestion appreciated.

 

[Kestas]

After 5-6 months the gas can start getting stale. I'd use up the old gas, get fresh gas in there, run it a while, then see if the problem clears up. I've had similar problems with old gas. The car will run on old gas, but it'll seem just a bit off, especially at cold idle.

 

[Volvohead]

Most likely STALE or bad gas. Even the NA I-5s need very good quality fuel to run right, especially on cold start. 87 is the absolute bare minimum; they run their best on 91 or better, even the NAs.

Drop some Regane or Techron in it as precaution and be sure to run a tank or two of premium afterwards until all of it is gone.

Also try resetting the ECU (a fuse pull) after this tank is gone.

If that dosen't solve it, then it needs to spend some time with Vadis/Veda. This vehicle should still be under warranty.