I posted about my '93 945 having tough starts on damp mornings last week. Well, I had many good suggestions most of which pointed at spark plug wires. I was fully prepared to buy anew set of Bougicord wires when I was faced with a difficulty in selecting the correct set from all the options out there. My car has a Rex/Regina ignition/FI with a distributor at the front of the engine. I found it very difficult to find a proper set that identified itself as fitting my car. Some Bougicord sets state Rex/Regina and some others state the chassis number range and I found both of these sets fit my car (my chassis number falls into the range specified). When I called FCP they could not make any more sense of this than I could. I did not want to order the wrong set and spend money on returns, etc. So, I opted to go the cheap route and not get a new set of wires at all. Rather, I got a new cap and rotor (which I was going to do in any case) and a new set of NGK spark plugs. I then took the old wires off, cleaned them and the contacts and treated the outside of the wires with silicone spray. I then installed the new cap, rotor, plugs and packed the spark plug end of the wires with dielectric grease. This was all done on the typical damp morning when the car refused to start (I tried starting before starting the work and no joy). After all was back together the car started right up and ran great. So, for right now I will stick with the old wires, but will do some more research on exactly what wire set I need from Bougicord. The wires I have now are Volvo branded Bougicord ones and I am not sure how old they are, so I still need to think about replacing them.

Here is one thing that puzzled me. Of the four old plugs (Bosch Platinum) 3 looked good, but one (cylinder 4, closest to the firewall) plug had a lot of ash-like deposits on both the center and ground electrodes. Could this indicate a bad spark plug wire? I will pull the new plugs in a few hundred miles and inspect them, of course, but it would be great to get some advice on this type of thing. This may be indicative of a bad wire, since it was the only plug that looked different than others.

Thanks again for all the responses and I am looking forward to some more wisdom.