I'm guessing you are not leaning the mixture like you believe. Look at the workshop manual D:04:01. Clockwise increases CO, anti- clockwise reduces CO. You should really check the CO by going through the full process. Also, the idle screw positions can affect the readings. Is the test you are going through at idle or under load. Harold McElraft - 3354 --- In dmcnews@xxxxxxxxxxxxxxx, "Adam 16683" <acprice1@xxxx> wrote: > My car failed emissions for THC and CO. It passed for NOx. > > My mixture screw was tampered with a few months ago (wish I NEVER did > that) so I am pretty sure this is the biggest factor here. > > What gets me is that I leaned out the mixture a bit (tampered with > mixture screw again) had it retested, and the results for THC and CO > were WORSE. > > The results for NOx and CO2 improved however, but these were already > passing. > > > Any and all input is appreciated! > > Adam Price