80TA

My 96 z is near stock.No mods on it that would make it go really lean.
I am getting quite a bit of knock sometimes 5 to even 10 counts or so.
Not every single time either sometimes none and sometimes it there.Very unpredictable.
I have lt4 km,checked to make sure nothing is hitting under the car.
I am running 92 octane.I have stock compression.
My o2 sometimes seem to show low readings like way way low but yet the knock is not always there with the readings.The car definitely slows down when you get the knock readings.
So suspecting fuel system problem.I have new gm filter to put in ,think just have some cheap brand on there but did change it out like a year or so ago.
Do the regulators go bad very often.Could a pinhole leak in the reg line or the line being off cause this lean condition and the knock?
Other options would be injectors car has only 60,000 miles on it so wasn't thinking they woudl be a problem and the car doesnt get the knock every time I test.I am using scanmaster right now so no logs.I do have autotap and might have to hook that up and log a few runs.
I am thinking changing to new injectors for planned mods maybe 30s.Are the svo fine or should I get the delphi ones like from racetronix?are they worth a bit more to get the delphis.
Also what fuel pressure should I be looking for at idle and under wot if I rig up a fuel pressure gauge?What is normal in these cars wot? My car starts fine,idles perfect.Doesn't seem to have any missing and doesn't throw any codes.I did have water pump go last year but my opti seems fine and if the car was not firing right woudl expect the car to be rich not lean right?

I dread doing a fuel pump as its a vert and so far no one has told me if they have done the trap door method in a vert.I would definitely be doing trap door if had a hatchback as its just plain ignorant of gm not to put in an access hatch like my dsm cars.

I did plan on better intank since got a zex wet kit to install this year too.
But might have been able to get buy with an inline.If my stock pump is weak will an inline fix the problem until guy changes out the intank.
and can these pumps get weak and make the car run lean and get knock retard?

I can also do a test at quarter tank with xylene or toluene have that stuff available near me at paint store.It gives like 100 octane at 30% ratio I think.

Injuneer

Since you're using a Scanmaster, can we assume you are see 5 to 10 degrees of knock retard? Under exactly what conditions? WOT? During shifts? Just cruising under part load? At idle?

Again, under what conditions? At WOT? If so, what are you considering "low"? Other than WOT, you're going to see 0xx mVolt readings quite regularly, as the closed loop control cycles from rich to lean.

I wouldn't jump to any conclusions, without more detailed info than you provided.

Stock fuel pressure is 43.5psi at idle, with the vacuum compensation line removed. Spec is for any reading between 41-47psi to be acceptable. Reconnect the vacuum line and the pressure will drop about 8psi below the "no vacuum" pressure. Tape the pressure gauge to the outside of the widnshield, take it out on the road to max load/high RPM and the pressure should hold within 1 or 2psi of the "no vacuum" reading.

80TA

Thanks for the pressure numbers injuneer.
Yeah I realize have to do more testing.OF course mean knock retard reading on the scanmaster.
I am running stock maf no real mods.Mods are g2 induction,holley filter,tb bypass,magnaflow catback,airfoil,have maft but seems to not matter if I set it rich or what sometimes I still get these lean weird values and sometimes it seems normal.I have it two clicks rich on wot right now base is not touched.Have stock injectors.I have also ran car with no maft connected as it shouldn't be needed with my current mods.Still same knock.
I realize 02 cycle .I am talking wot .No knock noticed at part throttle or idle.I had a hitting pipe on my crossbrace but spaced it down and pretty darn sure no way its hitting now.
Car has 60,000 miles.Seems to be running ok but does also seem to get a bogging when floored sometimes that many guys complain about.
I have never changed spark plugs or wires and not sure if former owner did.
I changed fuel filter to something at auto parts store maybe a fram or what.

I will try to check my fuel pressure pretty sure it has to be fuel related.On 92 octane and with the lt4 km doubt its much else.