knock retard because of motor mounts?

[rat_rod_russell]

Is is possible to see knock because of a urethane motor mount? I'm getting 3-4 degrees of knock retard in first and second gear but once I hit third fourth and fifth nothing taking it up to red line. My LC-1 shows a good rich mixture under WOT and perfect stoch switching during closed loop mode. Is this possible or is my lack of information and my creative imagination getting the better of me.

LS1 (out of a 03 Corvette)
Full 2.5 exhaust
No Cats
Long tube headers
Custom Cold air intake
Comp cams 224/230 112LSA
.612 lift intake /.612 lift exhaust
98 computer
T56 F-body
57 Chevy 150 Two Door
C4 Corvette suspension


Thanks
Russell

[TAQuickness]

I haven't heard of poly's causing false knock and I'm not having a problem with them on my bird.

If you pull 5* of timing from that range does the PCM quit reporting knock?

[rat_rod_russell]

I went to the drag strip to do some safe tuning, when I got there I had maybe a gallon in the tank so I bought 5 gallons of 110 Octane unleaded. It was my first trip ever to the drag races other than that one trip last week went to watch and get the rules. I made a few passes to get the hang of things then started logging.

With 110 the knock shows up in first and second but not third or fourth. One run it didn’t show up in second but showed up in third but not fourth. I took away 2 degrees of spark in the 4000 RPM range in all fuel volumes (I took it out of the high octane and the low octane tables) and it still shows up the same 4 degrees that showed up earlier in the day when I was running 93. It showed up in first and second but not third or fourth. I took another 2 degrees from that specific range and another 2 from all surrounding cells and the same amount of knock shows up at the same time and followed the same pattern. But the WO2 never wavers from 10.8-11.2.


So I’m a little excessive rich under WOT but under regular driving with Auto VE calibration it bounces around 14.6 perfectly then I moved my switch points for a little better fuel economy.

I did build the car from the ground up it there something that I might have done or not done to create this abnormality?

Other information I had Jesse at Wait 4 Me install a speed density tune to this 98 ECM, I also have a walbro 255LPH pump with Corvette fuel filter/regulator.

-Russell

[TAQuickness]

What's your PCV system consist of (stock, breathers, vacuum pump)?

[rat_rod_russell]

Stock 03 Corvette PVC

[TAQuickness]

You might look into a baffled and/or filtered catch can. The oil mist can cause false knock.

[rat_rod_russell]

Crap I didn't even think about that, thanks a ton I'm going ot try to have one on the car before the weekend and I'll get some more logs.

Thanks again
Russell

[duramaximizer]

So is that where jesse was going saturday when I stopped by .... LOL I was in need of an Lb7 ecm.....but he had none.

As always it was fun to look in his garage. :D

[rat_rod_russell]

I don't know I've never been. I get Hanna to rebuild my harnesses and Jesse to base tune odd ball stuff. I hope he didn't drive all the way down here

-Russell