I have a 99 vette thats maf-less but is in semi closed I guess you would call it. How often should it switch between closed and open loop and long should it take. I had a 02 sensor go bad so after changing it I was watching the 02's and cl and ol. When you start the car hot it stays in ol till you drive sometimes, other times it will switch right after you start it up. Whats making it stay in ol sometimes?