I've been trying to get my '84 240 engine to run right and it still is running a little rough. I've tried the following: changed plugs, checked plug wires, cleaned throttle body, checked that all fuel injectors are clicking, sprayed carb cleaner down the crook tube to the idle motor. Ive tried all of this and it's helped some but it's still not quite right. I've suspected that the oxygen sensor isn't working because I talked to a local volvo mechanic and he had me hook up a voltmeter to it and it wasn't reading any voltage. He told me that it meant that it was bad. If the oxygen sensor isn't working will it cause the engine to run rough? Thanks, Charles