was running premium in the base northstar 275 horse engine. switched to regular and recently noticed pinging, knocking going uphills and upon acceleration. didnt notice it before, might be coincidence or the regular gas. anyway, went back to premium, DIDNT fill up but just filled halfway and put in gas treatment. still knocking and pinging, any suggestions?

 

most cases it is because of regular gas, and having always ran premium. try some octane boost to see if that helps. if not, run a couple tanks of premium.... now if that doesnt correct your pinging., we'll address something else.
rickyd

 

can the engine be harmed in the meantime?

 

i wouldnt be horsing it.... ya know? thro some octain boost in it for now
rickyd

 

If you keep the load light it won't take long to get rid of a tankful. If you only put half a tank of regular in with half a tank of premium, your octane is about the same as the mid-grade-still not enough for you car it sounds. Light occasional pinging for a short time should not do any damage. It's the loud clunking kind of detonation commonly referred to as "knocking" that can do damage fairly quickly if really severe. You really control how much pinging goes on with your right foot.

chuck
98 Deville Concours

 

2000 and later designed to run on regular - 87 R+M octane, you may have got a bad load of fuel. Carbon build up or EGR problem could also be possible. Check for codes.