I need some help isolating why my car is pinging. Its not a real rough ping, infact I didnt even know I had the problem until i was on the dyno this weekend and could faintly hear it.

The car is completely stock except for the fact that it has a flowmaster exhaust from the previous owner. I took out the baffles recently but that wouldnt affect the dyno.

Also, I was able to get someone with a scanmaster to show me the readout of the knocking. When driving normally it hit up to 8 degrees. When i stopped and put the car in 3rd and floored it, it only got up to 3 degrees.

I only run 91 octane gas from either chevron, texaco, 76 or mobile. I was hoping i could of gotten bad gas from a chevron in a lower end of town.

Ive never had to deal with detonation before so im not to sure of any other symptoms. It kind of feels as if the car is hesitating when shifting from 3rd but other than that it could be me. I was told it could be the spark plugs so I will probably end up changing them within the next week or so. I dont think they have been done since the car was bought - 48,000 mi ago.

I would like to start out with the most simple things first, and then work my way up from there. Where should i start?

On my dyno graph, i wasnt able to see much of the knock as i thought.

 

Did you get an air fuel ratio reading??? Maybe you are just running really lean for some reason...

 

Unfortunately I had only paid for the dyno w/o a/f. I figured that since this was my first time dynoing and there isnt much done to the car that i wouldnt need it. Shows now that i was wrong.

Is there anyother way to check the a/f ratio?

 

You could use something like Auto tap to check the a/f ratio, but it won't be as accurate as if you were to get it checked on the dyno....