my volve has a weird hesitation on the freeway. every now and then it feels like someone hits the brakes for a split second, or perhaps engine power just cuts out briefly. there is no vibration (i.e. not an ignition problem), so I suspect a sensor malfunction either with fuel/air or the ABS. any ideas most welcome… thanks!!
I think you can rule out the ABS, but I sure would not rule out the ignition system.
While there is more to the ignition system, how old are the pugs and wires?
the wires are original (58,000 miles), and the plugs are new. it started a week or so after i had new plugs put in. I had the same guy who put in the plugs drive the car, because both our first thought was plugs, but he and I both have driven cars with one cylinder out and it feels totally different. That would rule out the wires as well. It does not rule out loss of spark on all 5 cylinders though, come to think about it. hmmm…
oh, also… if there were a misfire, the computer would notice and the CEL would come on. But it doesn’t. Have driven it hard to see if I can force the problem to occur (or for the light to come on), but with no “luck”. It’s intermittent, rare, always on the freeway, with or without cruise control.
I had the same car and we also have the S-60 2.5T, 2004…when it hesitates, do your RPM’s jump briefly and is it usually from a slow acceleration, like entering a highway or a residential area?