so, no replies to first post. no surprise since i have had several very good mech friends [not volvo specialists] unable to pinpoint the issue. i have hopes that someone with volvo computer knowledge can tell how to disconnect the mis fire feature. yesterday, pulling out into traffic, i inadvertently reved it to 4000. of course it set a check eng light, but i noticed the eng was pulling strong with no sign of misfire.having covered all the mechanical possibilities i could find, now am thinking some sort of computer error. the simple solution would seem to be to turn off the misfire function [if possible]. if someone could tell me how the computer reads misfire, that might help. any help would be appreciated