Hi, if the oil hasn't been changed recently then do so just before the test. Most of the nastiest emissions come from smeggy oil via the breather system especially on higher mileage cars, make sure the air filter is new also. (If desparate you can disconnect the crankcase breather and vent it to air but you must plug the hole where it connects into the intake). Some oils like 'Castrol High Mileage' are designed to reduce emisions. BP ultimate won't do the trick in a few miles, try an injector cleaner like Wynns or STP and do a tankfull of miles. I hope this is helpful.
|