Help me figure this out.

So A while back I posted about my car running badly while it was warming up.  Runs fine when cold and once up to operating temperature but anywhere in between it runs like ass.  So I started looking for reasons.  I unplugger the coolant temp sensor on the thermostat housing and voila.  runs like a champ, all the time.  Except for the shitty fuel mileage and the fact my A/F gauge tells me my o2 sensor responce is sluggish.  I buy a new sensor and it goes back to it's old ways, hesitating and such under patial throttle.  This must have happened to someone.  Help a brother out.  (there might be a cookie in it for you)

UglyoldnissanSo A while back I posted about my car running badly while it was warming up.  Runs fine when cold and once up to operating temperature but anywhere in between it runs like ass.  So I started looking for reasons.  I unplugger the coolant temp sensor on the thermostat housing and voila.  runs like a champ, all the time.  Except for the shitty fuel mileage and the fact my A/F gauge tells me my o2 sensor responce is sluggish.  I buy a new sensor and it goes back to it's old ways, hesitating and such under patial throttle.  This must have happened to someone.  Help a brother out.  (there might be a cookie in it for you)

hmm.  when you are WOT the ECU is ignoring the O2 sensor...it is kinda fucked.  are you by chance using a Bosch O2...that could be your problem...our cars only like NGK.  Other than that check to see how dirty your TB is, grunge could be plugging you up there...or even in the intake mani.

hmmm, i bought an denso o2 sensor for my 18det, but its the same part number as an 18et o2 sensor...so it is actually an 18et o2 sensor...yah, i worded that wierd.

I dont remember the effects of an open CHTS, but heres what could be happening. When the CHTS is unplugged, the ECU defaults to Open Loop (basically a factory determined set of parameters ecu cannot change based upon sensors) so what your problem could be, is a faulty sensor somewhere else along the lines.

Also, check the routing of your vaccuum lines. Believe it or not, on my SE, i had a horrible problem, turned out i had two vaccuum lines switched, and was operating the wrong things at the wrong times.