How important is it that the engine be warm while doing a compression check? I didnt realize I needed to warm it up first before I had all the plugs out,so I went ahead and checked it anyway.They are all between 180 and 200 except the third one back on the drivers side ,it was 100 I still believe that it is fuel that is fouling my plugs because they are dry and covered with black soot, not oil.I rechecked the one that read 100 two or three times,so I know the reading is right.How bad is this?

 

better to have engine warm, plugs removed and butterflys open when you check compression. as a rule the numbers don't mean much it's the differance between them that matters. within 10% or so is acceptable, so you're at or near 50% with one hole so i'd say you got something bad going on with it