Volvo: 1996 850 not starting, firing order, o clock

Question
Hi, I was asked by a friend to give his 96 850 a tune up.  We changed all the plugs, wires, rotor and distributor cap, started it and it was misfiring.  I rechecked the firing order but failed to follow that I was supposed to go counterclockwise which obviously led to the car not starting.  I maybe had a total of one minute of cranking with the order being totally wrong, then looked again and got the right firing order being 12453 counterclockwise with #1 cyl being at about 7 o'clock on the dist cap.  I've checked and double checked, pulled out and wiped fuel off plugs but it still is not starting.  It wants to start but wont.  He was told his O2 sensor was reading a code as well.

Have I possibly damaged his engine by not having the proper firing order?  Would any of this lead to the O2 sens getting worse and not firing at all?

Thanks
James

Answer
James,
I doubt there is any engine damage. If there is too much unburnt fuel leaving the exhaust the HO2S reads that and in time might harm the sensor. What may have happened is since the engine did not run but fuel was injected into the cylinders it washed out the oil on the rings and lowered the compression enough to keep it from starting. Get new plugs pull out the old ones let the engine sit overnight without the plugs to evaporate the fuel, give each cylinder two squirts of oil turn over the engine by hand or with a starter button, so you do not use the key and inject more fuel. Install new plugs and see if it will start. After running the car for a day deal with any new fault codes.