Hey guys, I have a 2002 xc70 that I got recently, and after some off-roading in it I noticed my idle was rough. I brushed it off and hoped it would go away but it didn’t. The interesting thing is I don’t have a check engine light, it came on once and flashed a few times and went away as I got on the freeway. It is only rough at low rpms, and once you get above 2500 or so it’s smooth again. I’m thinking maybe a vac leak? Or one of my injectors or spark plugs is messed up. Any insight would be appreciated!!

 

A good first step would be a scan with an appropriate scan tool. Any codes or pending codes might point to a specific cylinder. For basics - how old are the spark plugs? Coils are a common failure - but can fail due to extremely worn plugs. So start with the basics.