80TA

I am starting to wonder again if my scanmaster is screwed or what.
I get knock up to 12 counts on my scanmaster but I have low 02 readings most runs like .853...870 , so figure my fuel pump is fubar.
But just scanned a 95 lt1 and it also has like up to 12 counts but it shows much higher 02s like .923 ,.915.. We both are running premium gas. Cars are close to stock modwise that would affect air /fuel and one car has 90,000 miles on it and mine 60,000. I have fan control and 160stat and thought that might help ,his has nothing. I have tried a few types or 91 or 92 premium with no luck on the knock.

We are staring to wonder if due to high gas prices we are getting stale premium. Also wondering if going to a 160 stat and fan control in his car might help. I doubt he has rich knock? I thought the knock might be just at shift points but doesn't seem to be .It happens when we go wot.
I could possibly try colder plugs but they are not easy to change in these cars.

Maybe he has something knocking under there have to check.I checked mine and can't find anything that would account for it.

I have one more buddies 94 to test out of curiousity. How many counts of knock will hurt power? The car does seem to be doggy at least mine when it does hit 10 counts or think it even hit 12 counts once or twice.

I have the lt4 km in my car and he doesn't in his 95.

I am thinking maybe carbon on pistons in his car for sure and maybe mine .If you do the decarboning you have to change out oil and plugs right.?

I have one other option to try can maybe lower timing with my maft and see what that does. I don't have the maft hooked up and not the timing control part but could do it I guess. I did try to richen up my car to get rid of this knock and it didn't seem to help again maybe due to my fuel pump being weak.

Injuneer

First, you need to get the terms correct... minor point, but the Scanmaster measures "degrees of knock retard", not "counts". "Knock counts" is something different, and the Scanmaster can't display the count.

Any knock retard reduces power output. My 94 had a minor amount of knock retard with hard, lifting throttle shifts. Seldom had any at other times. I don't think I ever saw a value of 12deg retard on the Scanmaster in all the years that I used it. I did get a bad tank of premium once, and it showed up immediately as 3 to 5deg of knock retard with the slightest pressure on the throttle. Some octane boost helped minimize the problem until I could get a better tank of fuel.

I doubt you will see significant loss of octane in the brief period of time the fuel sits in the station's tanks... even if they aren't selling a lot of premium due to the price - definitely not in multiple stations of different brands. Put some 100 octane in and see if it eliminates the problem. That would confirm true knock.

80TA

Ok sorry it measures knock count in my 92 talon not sure what it does in my ls1. Have scanmasters in those cars too..Love my scanmasters!!

But yeah have seen 10 to 12 in both my car and that guys 95 z.

I will pour in some xylene or toluene shortly in one or both cars and see what happens.

I will still get fuel pressure tested just having trouble getting buddy or speed shop buddy to test it and too cheap to buy a tester right now.

His 95 has high 02s so his knock may be from something hitting..maybe exhaust he has flowmaster on his car.

Can simply louder exhuast like my magnaflow cause this knock problem ?
What is a good timing on these cars stock wot say in a quartermile run?

Anything else other than my exhuast hitting cause big knock like this ?
Engines sound fine..