So I've been having some trouble. I'm considering buying the Phormula knock analyzer because this is very frustrating (maybe I'm overlooking something simple) but before I do maybe with a little advice I can tune it out. Anyway I posted over at the engine forum and since then I have noticed that free revving I get counts if I press the throttle fast, if I do it very slow I don't. Same with acceleration. Seems to happen primarily after an AE event, I have a 383, 454 tbody 1" spacer and performer RPM intake, Etec heads breathes well cam is a comp xfi260. Anyway I initially thought perhaps the DCR was to high, maybe it is. I retarded the timing and added a gallon of torco race mix to 20 gallons of fuel and still got counts however not as much. When I do say 1/3 throttle for 3 seconds and let off suddenly ding goes EBL KC. I'll post my timing table, DCR, knock counts, and a data log. I've removed 20% of the TPS AE I'm using since it dips to low 11 for an instant thinking perhaps too much fuel, not sure can't seem to figure it out.

 

http://www.filedropper.com/lesspark4th3 That a link to file dump. I'm going to pick up a 160 tstat right now and see if that helps along with running a coolant bybass, running a 180 right now.
Thanks in advance for any and all advice!!!
Frustration mounts, got new engine in, new tranny, and tranny blew after 2 weeks, anyway at least it's back on the road.

 

Put 160 stat in was a 180, and reduced timing to 23-26 degrees, actually knock counts are much better now. I'm going to run a coolant bypass tomorrow, maybe that will help more too I don't know I don't have one since it's a vortec block. Since I set the timing to 23-26 all around and 160 stat it has been better maybe my dist needs to be replaced, I do have the dist latency set correctly I believe. Still maybe my DCR is too high, hence the need for less spark advance, cool temps ect.., Or it could be a hot spot in the passenger rear cylinder from no coolant bypass.

 

So reducing timing and cooling the engine better has helped, however I still need to determine the root cause of the counts. One thing I did notice today is a pattern -it happens on AE events, interesting. So dist latency, cooling, timing, fueling (never thought a dip to 11 was going to be bad perhaps- though more fuel less knock). This is the first time I've tuned so I thought I was close before guess not, oh well I'll keep plugging away.

 

It seems to me that you are getting both real & false knock. The quick let-off and getting knock would be false.

Tip-in is possibly real.

Are the etec heads CI or aluminum? If CI, they might be timing sensitive. The GM Vortec heads tend to be.

May need to put some new plugs in first, but a sign of real knock is flea sized black specks on the center porcelain.

RBob.

 

I will put new plugs in and see what happens. The heads are aluminum Edelbrock Etec 170's, so they are fastburn style. As I understand they are a better flowing aluminum style vortec head. Thanks for the reply, I will pull pugs and post back.

 

Starting to think dist latency may be an issue, since running with a flat table and new cool 160 stat removed almost all KC. I'll post a zip of the log with a mild vortec table, and latency image. The reason I'm thinking latency is the areas of spark counts happen where the latancy is higher in the table, my dist is fairly new and hooked up a timing light and attempted to rev engine along with watching commanded timing hard to tell but seems to jump around. I read the experiment on latency post that sparked my curiosity. has anyone else had a problem or had to adjust the table? vortec spk tbl.zip