Is the EGR valve controlled by vacuum or by the PCM through a motor/solenoid? If PCM is it used in the first few minutes of run time?

 

the egr is controlled by a pcm activated solenoid that controls the vacuum going to the egr valve. hows that?

the egr is not used until the motor is run for a certain amount of time and you are cruising, map is steady, tps is under a certain percent, and the motor is warm.

 

Wonderful!
What is warm? Mine sputters after about 1-2 minutes. But it is real strong until then. But it is not up to 180 yet. Would a bad EGR valve that doesn’t throttle the exhaust correctly cause this?

 

well, that is the way it's explained to work in my 97 service manual, just tried to find the parameters for it in lt1edit and all i could find was the map readings.

I don't think the egr kicks in till closed loop, sounds like that's where you're having trouble. you need to get a scanner on your car to see what's happening andn go from there.

 

acualy the PCM runs an EGR flow test sometimes at startup during closed throttle.

YOu could have a leak in the egr valve pulling air in tho. you can check that with carb cleaner