I've been trying to get my new 93 940 with Regina ready for a 2nd emission check after a failed 1st (high CO, HC and NOx at 40 km/h). The car started and idled well but seemed to miss at around 2000 - 2500 rpms and chug on deceleration. Even though the car looks well maintained, I think the previous owner let some basics slide and did not drive the car much recently. Here's what I've done:

-checked and cleared coded, nothing came back
-new rotor and cap, old rotor was pitted
-new plugs, old ones had evidence of a rich condition especially cylinders 2 and 3
-checked for vaccuum leaks and ended up tightening most of the valve cover and intake nuts
-unplugged every sensor and checked contacts
-checked all grounds
-tested O2 sensor
-oil change, oil looked old
-the whole exhaust from the Y pipe on looks almost new

After all this the car ran better and gas mileage improved but still some missing at 2000 rpms. Then I swapped in a different RSR and the engine missed worse at 2000rpms - aha, I said and swapped in another one and the engine ran much better. Later today I'll find out if that did the trick with regard to emissions testing.

Ron

93 245
93 940