Hey guys and gals,I have recently purchased an 96 3000gt and it was running rich ,put on data logger and found the o2 sensors between .9and 1. or higher ,and the fuel system in open loop mode after warmup.Some times it clears up and runs real good for a few seconds and then back to rich and rough ,high idle.Already replaced tps,and I cleaned the IAC.Idle was better for a couple of days but returned back to a high idle soon after.I am sure the replacing the IAC would correct the high idle prob but does it have anything to do with it staying in open loop?I really want to start driving it but with it rich I dont want to damage anything mechanically with it the way it is.HELP HElp please.

Is the car overheating?

Your 02 sensors could be bad.

if you are using logging sofware your O2 should be cycling at hot idle between 0 and 0.92 if its not your O2 senser needs replacing, I have just replaced mine and its made a big difference in all respects such as idle, cruising and under high boost, I had sooty exhausts since fitting the new one I have done 300 miles and there are still clean

No its not overheating ,just real rich and rough idle ,with high idle at times.When its cold or start up for the first time it runs fine ,maybe ten to thirty seconds later then you start seeing black smoke then eventually after about a min it starts the rough idle,That is if it isnt already running at 1500 or 2000 rpm.When it high idles it seems to burn most of the fuel of coarse but its some times it idles around 750 and thats when it is rough .Thinking I should replace IAC for the idle problem and I am thinking of air temp (Its in the mass right ) or the mass sensors for the open loop. I will try that this weekend and post the results. Also I did check o2 or accually a friend did and said they were working fine,Since I believe the o2 data is not used till warm up and the fuel is passed over to the ecu ,I am leaning on it being a sensor with the air temp or other sensors in that process(handover) .There was a reciept in the glove box for four new ones from the dealer two pre and two post cat sensors.Cat is almost brand new looking inside ,I took them out and they were not very old either.I believe the previuose owner had put something like 7900 dollars in it at variouse dealers trying to get the car strieght for his kid.Anyway hope I didnt write too much new to the forum world.thanks again everybody.

let us know.