I'm running into a problem when the car transitions from closed to open loop under partial to moderate load driving conditions. The car will buck and studder, it seems to be totally random. I'm not clear on when the car would change to open loop except cold startup and WOT.....What should I be looking at to help solve this problem? Right now I'm trying to work on my LTFT's and get my VE table right but this problem doesn't go away.. The combo is a stock shortblock, vortech v9 running 4psi, pacesetter longtubes, fm-7 cam, I *believe* #38lb injectors, highflow y pipe. The car will pull pretty well after it gets past the studdering when it gets to OL, but it just runs like a bag of crap when it does so. Any ideas on where to start? What would rescaing my IFR do? I'm starting with a stock 99 ls1 camaro ss tune. I have to attack a hot idle problem after I get this figured out. I also know I should have a WB02 but right now I cannot afford it. Any ideas/help/reading info would be appricated. Thanks

 

Try logging engine>emissions>evap purge % and see if that changes when you go into open loop. Also try disabling engine>fuel control>cot lean cruise>cat overtemp protection and see if it goes away.