That hole is supposed to be kept closed except when actually adjusting the mixture screw after which you MUST reclose the hole and measure emmisions again. It is not exactly an IDLE mixture screw, it affects the mixture across the entire RPM range. It is only adjusted at idle. Your problem *could* be a dirty/bad injector. Or a vacuum leak possibly including the seals on the fuel injectors. The mixture screw is a metric allen screw (I think 3mm) and it is probably in there. Make sure the frequency valve buzzes, even at idle before you try adjusting the mixture. The mixture screw is VERY sensitive. It takes only a little bit of a turn to mess up your emmisions. Generaly it is best to leave it alone and fix the problem that causes you to fail, not try to adjust it to fix it. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "vin4258" <vin4258@xxxx> wrote: > > Vin 4258 failed emissions a few weeks ago and after doing a tune up > (plugs, wires, cap, rotor, air filter, oil) it failed again today with > only minimil improvement. Emissions tester says he thinks the O2 > sensor is ok because emission levels pass at high RPM (the > sensor 'kicks in' at a higher RPM but does not affect idle mixture?) > Next option is to adust the idle mixture screw, but when I go looking > for it, it seems to be missing. All I see is a hole with no apparent > end but I do see threads. What is this and can I simply put in a > 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/