Well you got colder denser air going into there. Something is still causing a problem though. Those 3.1's are not a high compression engine.
Check the EGR. No EGR will give you a ping at part throttle.
Isn't the formulation of winter gas different than during other times of the year? Have you tried a different brand? I have a tendency to be suspect of some gas, I mean how can we tell if their octane is really what they say it is? Isn't it possible someone made a mistake and mixed up some low octane with what was supposed to be high? Also, carbon buildup can cause preignition, there are various products/methods to help clean the engines's top end but while many have reported success with same some have also said the pinging came right back. Some GM mechanic posted on one of the ng's about torn down engines in the northern US during winter exhibit a lot more carbon buildup.
because
A 97 is OBD2 so a scanner will tell you. It has an electric feedback EGR.
Premium gas eliminates the ping, I have tried different brands, sometimes goes away with midgrade gas sometimes comes back. Its not excessive but can become annoying at times.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.