"Not ready" message

[gene.pomeroy]

My sister's 1998 Buick Regal is due for Emissions Testing, and I went with her to pay and such, did a 20 minute drive cycle on the freeway staying at 55mph, went to the center and we got the "Not ready" message for the OBDII test, did another driving cycle of 55mph for another 20 minutes as recommended and went back, another "Not Ready" message. I talked to my dad who is an ASE Master mechanic and he is stumped. There is no check engine light, or any light of that sort on the dash either. Does anybody have any suggestions on what can be done.
~Gene

[maxwedge]

A good scanner will tell which emissions sensors have not come online, this occurs after clearing codes and/or disconnecting the battery. there is a specific GM drive cycle to get these to come online. You can find that either on a site search here or google.

[Tech II]

Best way to do a drive cycle is from a COLD start.....

Start the car, and let it idle until it reaches normal operating temp, 190F....

Then go out on the highway........get it to 65mph, coast to 50mph......repeat several times, then get off highway....come to a stop....put in Park.....wait 30 seconds......get back on the highway and come back, and repeat the acel/decel 3 times, and then get off the highway....come to a stop....put in Park....then go on your way....this usually works....