I have my car running not bad I think with newly installed 30 pound injectors and maft to tune them with. I have scanmaster .I am getting a few weird things.
When car is cold it seems that I get high knock like 11 on scanmaster and at same time sometimes rich like 924 o2s. Then leaving maft as same setting when the car warms up a bit more it seems the knock goes away and I get like around .890 02s which is pretty much optimal.

Also quite frequently the scanmaster gives me some bizzare number for 02 like .641 yet the knock is zero. I think buddies scanmaster in his 94 also gave weird numbes and think other buddies 95 also gave the occasional weird numbers with my scanmaster in his car.

Is this normal for the scanmaster in lt1s to come out with stupid o2 readings when wot sometimes. and other times be right where the should be and how can I show like .924 and have big knock and then show .890 and have none a short while later?
I am thinking mabye my 02s are getting old they are original and car has 66,000 miles on it.

Its making it a bit hard to tune with the 02 reading strange sometimes.

 

Fromt he way your describing it sounds liek your o2's are staying steady?. Are they not bouncing around?. If everything was fine your o2 readings on the scan master should be eratic and never stay on one number. Thats if your car is going into closed loop. Soemthing doesnt sound right.

 

I think he's only talking about WOT.... that's what he mentions near the end of the post.
You can't relate knock specifically to A/F ratio... its just one of the factors that influences it. A simple misfire could produce a "lean" O2 reading as the unburned O2 goes past the sensor. And that would not be a true lean condition or contribute to knock.

Your "cold" knock may be piston slap setting off the knock sensor. Hard to evaluate it any more fully than that form the info given. The ScanMaster just tells you what the PCM is reporting.... can't tell you if the data coming from the O2 sensors is correct.

 

I was talking about wot only of course. I know they jump around normally and they are jumping around.

I wanted to change them out but they seem to be welded in there.. I figure might as well do them when do some mac headers as well as doing new plugs then and wires or delteq conversion.

I don't get any misfire codes thrown. I haven't noticed any piston slap either like my 99 ta gets. I did read a post where guy got rid of his knock with lifter change. I also have a 305 comp and likely will change out lifters when do the cam I think next year. These lt1 engines are so much fun to work on thought would do heads,cam and headers all at once to save aggravation.

So do any of you other scanmaster guys get super low 02 readings sometimes on the scanmaster like in the 700 or 600 yet show zero knock at same time. Heck I don't even see the 02 go to those numbers when watching it. They seem to be reading normal range but the scanmaster comes up with this .641 out of the blue it seems. I can't see the scanmaster being faulty it reads everything else fine. My ls1 scanmaster doesn't do this though it reads what it should no funny o2 readings. And knock is zero around .890 mv with 92 octane in that car like it should be.

 

I think you're putting too much emphasis on thinking that if its lean it HAS TO knock... not true. I review data logs for people. I've seen logs where the WOT O2's fade off (at least on one side) to 200-300mV, and there is absolutely "0" knock retard. That tells you the engine isn't necessarily on the ragged edge... timing isn't that aggressive, inlet air temp is reasonable, coolant temp is low, fuel has adequate octane, density altitude is hgih.... all of these things can mitigate knock.

It could also be bad data.... the sensor could be seeing air that's getting into the exhaust, but not through the combustion process. I've seen a lot of "crazy" things in data logs.... some of them can be explained, others can't.

But don't just look at the O2 snesor's low reading and assume it must be wrong because there is no knock retard at the same time.