When i first start the car, it's fine, and it's fine until it hits around 180 degrees. THen it stumbles and sputters under load. I think i may swap the opti, but why does it run fine when it is cold. Could this be something with the emissions and the open/closed loop thing? Possibly EGR? the cat is gutted, so i know it's not that. Any ideas? I need to fix this thing by this weekend. Any input is greatly appreciated. Thanks.

 

It sounds like you are getting the problems after the car goes switches the closed/open loop setting and starts relying on the sensors and readings to adjust the car's setup. Maybe one of your o2 sensors is bad and it's not reading the right amount of oxygen, or you're having fuel mixture problems. If it's doing it under load, that could indicate clogged injectors or something related to not enough gasoline getting put in the engine. Just throwing out some thoughts.

 

I would think that it could be either O2 sensors or fuel system. The O2 sensors dont do anything 'till it goes into closed loop, which is when the PCM starts to use them to adjust fuel trim. Thats why it runs fine 'till the PCM starts to try to use the readings from the O2 sensors. There is a way to test the O2's with a multimeter...it should be aroiund here somewhere.

Also, when the car starts in open loop the fuel mix is richer than when it goes to closed loop. When the mix leans out, that may be when your possible weakness in the fuel system shows up.

I would suggest:

a. figure out how to check the O2's and chekc those out (no need to spend $100 on new ones if you don't need 'em)

b. get a fuel pressure gauge and check that out

c. check for vacuum leaks, since these are common on our cars and very easy and cheap to fix. Check the EGR valve for sticking, check the EVAP canster, and chek all around the throttle body and intake elbow for tears or loose connections

Just my two cents worth, hope it helps

 

ttt....any other ideas, O2's may be bad, but they are less than a year old. I was thinking EGR also, but how do i check it and where the hell is it, behind the intake under the cowl?