They ground all the sensors and switches on the engine. At least those that need grounding, i.e. most of the ones with two wires on them. The ground wire with the red jacket on theback side of the passenger side intake runner grounds the ECU - i.e. the frequency valve computer that is run by the O2 sensor. So - yeah the engine might run with all that stuff disconnected but it may not be happy about it. Did you check the interior ground at the bulkhead - BOTH inside and outsideand to the frame below the water bottle? That causes about the strangest stuff on the car. dave --- In dmcnews@xxxxxxxxxxxxxxx, "drdhdmd" <doctorDHD@xxxx> wrote: > Does anyone know specifically what the black ground wires the bolt to > the intake manifold are for? > > My car seems to run fine (well maybe I should say, still runs the > same) without them grounded. > > (Except for the intermitant tach / idle flicker which persists despite > replacing the ignition pickup coil.) > > D² & 6530 To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/