Hey Folks.

Well, another bright, shiny COLD day here in Michigan....

I have an 88 Firebird Formula 350, auto, w/A/C etc. The problem I am running into is after the car "heat soaks" for an hour or so after driving for a while. (engine up to operating temp) When I go back out to drive it, it will start fine, idle fine for about 2 minutes, and then start dieing. Idle will "hunt" and the car tries very hard to stall. It has been doing this since I got it. I have done a complete tune-up (a couple times, had the car for a while now) and have replaced the 02 sensor. The problem seemed to be a little better, but, still present. If I hold the gas, or simply drive for about 2 to 3 minutes, it is like someone throwing a switch, and the car runs fine again. (for 178K miles, it runs REALLY well)

In any event, while at work one day, I needed to test our scanner to verify that it was indeed working. So, I plugged into the 'bird, and noticed that the O2 sensor sticks high when first started with a warm engine. (the car had been sitting for less than an hour when I tried this.) Then, BLMs and INT started to go WAY down. Amazingly enough, the idle deteriorated, and the car wanted to stall. Run the engine at 1500 rpm for a minute or so, O2 sensor starts playing nice, and the car magically starts running fine. HHhhhhmmmmm.........

Ok, now comes the fun part.... How on ***'s green earth do I fix this? A new O2? seems that replacing it the last time did not help.... Reprogram the prom to wait longer before going into closed loop? (this would be fine if I had the stuff to do it......)

I am open to any/all suggestions. (well, ok, maybe not ALL suggestions.......)

Thank you in advance for your assistance in this matter. Please read the disclaimer at the bottom of your screen.

 

Is the eng stock?
How far down do the BLMs and INTs go?
Does the coolant temp indication on the scanner look realistic?

Some datalogging s/w would be handy to t/s this problem.