The car has sound 250 000 miles and still runs great - averaging 29 mpg. But it recently developed a frustrating problem - sometimes it does not start. A starter cranks the engine, but it does not start. Sometimes, after 5 to 10 attempts it comes alive and runs like always. It never stalls. Sometimes it takes a couple of hours before the car decides to start. While starting in vain, I can eventually smell the gas - thus I would relate problem to the ignition. Last week I pulled out a coil cable and checked the spark. It seemed that it did not give any for a few seconds, but then came nice and strong spark. I inserted cable back to the distributor cap and Volvo started right away. I pulled out codes P0102 and P0422 (which I think could a result of unburned fuel in the exhaust), Anyone had a similar experience. Where to look first? The problem usually occurs once in every two weeks.