93 bonneville SSEI
Every morning when I wake up for school, I goto take off in my car. It runs bad out of hell(good) till I go about 5 miles and the motor gets warm it starts running crappy. It doesn't accerlerate near as much as it does when the motor is cold (like letting the car sit over night). I just changed the plugs, plug wires, oil, filter, oil filter. New rebuilt transmission. No codes.. any suggestions on what I should start out checking.

Id look for a possible fuel contamination problem, like rust in the rail or tank.

Mine does the same. I've never found a good fix.

Once mine goes into closed loop it runs like a completely differnt car also. The acceleration and power just arent there! I wish there was something out there that would narrow the gap a little.

Agreed... While it'* in Open Loop (warmup) mode, I wonder if there are sensors whose signals are being ignored, and after the temperature sensor says that the engine'* warm, a different set of parameters take over, and some tired sensors start handing in bogus readings.

Has the oxygen sensor been replaced recently, for starters?

no, that may be somehitng i need to look into tho. any other sensors you can think of while im out 'sense'itizing?

You wont have as much power because the engine is much warmer and the air isn't as dense.

Keeping the engine cooler is the biggest key in keeping your power. My 180 stat and 24k tranny cooler helps keep that down and i have a much smaller loss of power.

thanks. but i already have the 180* Tstat and a tranny cooler. i drive in Rush Hour in the DC Metro area, the second worst rush hour in the country. i spend most of the time over 200* F. no matter what ihave to keep it cooler its impossible. on hot days over 90*, i will be up to 220* sitting in traffic. Then when i want to get up and go, nuthin'. :? maybe its idiot protection so i dont blow my car up. :P

wouldnt it be 3 core if the tranny cooler runs through it? Im not sure how to tell by looking. i try it with the AC on and off all differnt ways. SOmetimes when i turn it on the temp goes down for a minute then shoots way up (If im sitting). my poor car has seen a lot of tough miles thats out of her 120,000, thats for sure.