Timing ...help!! 94 k1500, 5.7, $OD, 7427

[dispoejoe95]

So, I've got knock counts...alot of them... and I keep getting a handful of cells showing knock retard. I'm starting to think my issue is probably mechanical (bottom end) but I am hoping I'm overlooking something in my tuning. I get the knock retard mostly in the load area (high map / 1600-3600 rpm range). I've continually adjusted the open throttle SA pulling timing out which has only helped a little. I started with a standard vortec timing table and have since slowly pulled timing out. Today, fed up I tried going all the way back to my old swirl port head SA table and the knock retarding was worse or at least more frequent. I'm puzzled because I can't even hear the knocking or pings, not even a little..

So, in regards to timing, I have only adjusted the open and closed SA tables.
- Is there another table (or anything in the bin) that I should be looking at?
- I have eliminated the EGR (and changed a few things to shut it off so i won't get a code), is there something i need to change because the EGR is off?
- Is it possible the knock sensor is bad? It is aftermarket.

i know I'm grasping at straws here guys...I really hate the thought of pulling this engine, especially if it is a programing/tuning issue.

As always, I truly appreciate everyone's help & opinions. Here is a list of the changes I've made.
Vortec heads
Roller Cam (GM #14097395)
-Duration 196/206
-Lift .431/.451
-LSA 109
GMPP Intake (GM #12496821)
TBI "Ultimate Mods"
EP377 Fuel Pump (Currently set at 22psi)
Hypertech Power Bowl
Shorty Headers
Upsized Y-pipe (2" to 2-1/4')
Eliminated catalytic convertor
3" Catback
Eliminated EGR

[BigBanks78]

Keep pulling timing down in that area to see if it stops. My dad thinks his roller rocker arms my be to noisey, he is having same issue, vortec v6, 427 ECM. He tried corvette knock sensors but ECM didn't like them.
I am by no means an expert tho!!!

[sturgillbd]

How did you eliminate the egr valve? I ask this because if you just turned off the error code, the PCM is still going to use the egr routine. Make sure you maxed out the Temperature for EGR On scalar. I also maxed out the Minimum Speed for EGR scalar.

Brian

[dispoejoe95]

How did you eliminate the egr valve? I ask this because if you just turned off the error code, the PCM is still going to use the egr routine. Make sure you maxed out the Temperature for EGR On scalar. I also maxed out the Minimum Speed for EGR scalar.

Brian

Pretty sure I made those changes to the egr but I will double check my file when I get home.

[BigBanks78]

My dad was reading about a corvette with stock roller rocker arms had to make some knock sensors that were less sensitive so they wouldn't pick up rocker arm noise.

Notsaying thats your problem just that if you pull timing and you still have same knock go over mechanicals!!

i keep having software problems that turn out to be mechanical :-)

[dispoejoe95]

Big....It is certainly worth looking into.

Btw, Brian, I double checked and I have already made those changes for eliminating the EGR. I thought I had...I'm sure I read to do it on a thread somewhere in this forum.

Thanks for the suggestions guys.

[dispoejoe95]

Keep pulling timing down in that area to see if it stops. My dad thinks his roller rocker arms my be to noisey, he is having same issue, vortec v6, 427 ECM. He tried corvette knock sensors but ECM didn't like them.
I am by no means an expert tho!!!

I had thought about double checking the adjustment on my rockers but Is a knock sensor that sensitive that it will retard the timing because of rocker arms or lifters being a little noisy?