Basically stock 94 Formula...Cat-back and CAI...92 shell octane.

I had datamaster on it the other day sitting in park and logged some warm runs. From around 4k and up I am getting 10-12 degrees of spark retard. Also getting a high knock count of a few thousand blipping the throttle to redline 4 or 5 times.

I want to get rid of that garbage, but first I need to find out if it's false or real knock. No audible knock, of course. Exhaust doesn't leak when warm. I do have a few rockers the tick a bit...I need to pull my covers and set lash.

Other than that, I have the LT4 KM on the way...Not sure how much it will help, but we'll see.

Basically taking pretty much any ideas at this point. How do I tell if this is real knock or just false garbage? I have Tunercat, Datamaster, and an AKM cable to tune things out if needed.

TIA guys...hopefully I'll learn a bit about tuning and such with this.

 

Would an Octane booster be something to try??? I'm thinking if I up the octane and still get the same knock retard then it is true knock. Is this thinking correct?

 

The only thing you can do is put in some race gas and see if its real or not.

 

What about pulling timing from the computer. I can pull 5 degrees or so from the RPMs that are supposedly knocking and try it.

If it's real knock, that would likely get rid of it, right? Then I would know what it is.


P.S. the knock count only jumps between 4100 and 4600 RPM. Hell, by 5350 my knock retard is back down to like 3 degrees and falling.

Am I just getting some kind of resonance around the mid 4000s that is causing a vibration? If it was real knock, I would think it would keep knocking up to the shift under WOT.

 

Dont play around with the timing, just find a VP fuels near you, or order some street blaze 103, it's unleaded race gas that wont mess up your o2 sensors. See if it is still pulling timing (im 95% sure it still will), then you can plan your course of action from there. My car was pulling 4 degrees (maximum it was allowed) from 2800 all the way up the rpm range. I put race gas in it, and it did the same thing.

 

Just make sure it's UNLEADED. I've been through this and wiped out the O2s with one tankful. Although, the smell of the exhaust is great, lol.

Trying to up the octane level with boosters is almost impossible with how little they actually increase it per bottle of booster. You need to read the lables. I believe it takes 10 points to actually raise the octane level one number.

When you blip the throttle, you are most likely enabling "burst knock". The timing retards when there is a quick change in the % of air passing the MAF.

I have the LT4 knock module and I still needed to delete ALL the timing retards ( knock, burst knock, lo octane, temperature, traction control, abuse mode, stall mode, and max retard).

Retards can come from an improperly balanced rotating assembly (notorious for stock LT1/Lt4s) a flywheel put back in the wrong holes, a stiffer clutch, chattering pilot bearing, long tube headers, shorty headers, leaking exhaust gaskets, higher lift cams, noisy rockers. Basically anything that will cause a frequency in the water jackets that the knock sensor will pick up.

I've had mine dialed out for about 1-1/2 years now with no problems. I've even blasted it with a 175 shot (retarded 10 degrees with an MSD) without any problems on 93 octane.

 

I'm just going to do the race gas I suppose to make sure it is false. Then, I'll tune all of it out with tunercat.

I'm confident it isn't burst that I saw on another run through first gear I did. I squeezed the throttle due to sort of dusty roads from winter salt. It hit WOT at about 2500 and the retard came in at like 4200.

Am I right in figuring that if it was real knock that I am seeing, the knock would continue up to redline? I don't see it knocking around 4500 then stopping past 5000.

 

No. The KS/PCM are doing their job by stopping the actual knock. If it hits at 4500 you'll see timing backs off several degrees depending upon how bad it was. Many times that's it--the knock stops (knock count doesn't increase further) and the knock retard is gradually reduced (putting back in timing) until you're back to the original timing map. In every case of this I've seen on my own car with two different motors, the knock has been real. Reducing the timing at that RPM vs. Map in the timing table took care of it.

If the knock count keeps going up and up throughout the run, it's either false or you have way too much timing, bad gas or something else going on.

 

Excellent deduction. When I get my new motor together, I was planning on to putting all the retards back in and starting over. I'm pretty sure my knock issue was due to a poorly balanced / poorly re-installed flywheel.

You're the first person who was able to give an excellent idea if it is false knock or not.

Great Job!

 

Glad I could help.

 

I've had false knock due to many mods. It was pulling timing. Zeroed the knock table with LT1 edit. Is it possible to disconnect the sensor, or, will it throw an error code?

 

if you disconnect it will automatically pull 15 degrees