Too Much?

[Paul Clark]

Would someone please explaing to me how too much octane or too much alky could cause knock?
It has been suggested to me several times that this could be the cause of my knock problem, but I don't see how.
Bogging, fouled plugs, smoking, loss of power - those symptoms I could understand - but not knock.
Pardon my denseness.
Thanks

 

[Quiky One]

Sure, the higher the octane the slower it burns. If the octane itself cures the knock and you add alky then it burns even slower as methanol has an octane rating. You can also get knock from being overly rich. I've had knock before when my o2's were in the 900's. Dropped them down and knock was gone.

Jason

 

[Paul Clark]

Thank you, Jason.
Just wish I could find the perfect balance again.
I've shut off the alky and ran the 110.
Still got knock.
Seems a bit like Goldilocks and the 3 Bears.
This one's too soft, this one's too hard... etc.
Appreciate it.

 

[Quiky One]

How much boost? How much timing? Who's chip? What are your o2's?

Jason

 

[Paul Clark]

Only about 17 lbs.
That's as far down as I can back off the HD actuator.
Eric's chip for alky. (same setup that went 24 lbs. before on 93 and alky with zero knock)
Over 800 02's with a lot of recorded knock.
Casper's gauge reads red and the siren goes off.
That's with 110 and the alky shut off, as a check against false knock.
New knock sensor goes in tomorrow, to eliminate that variable.
There's a gremlin in here somewhere.
Help me find it.
Wondering if the injector harness is too close to the knock sensor. ???
Thanks

 

[Quiky One]

FYI, knock sensor is 14 ft/lbs. Why did you mess with the tune from 24 psi and 93? Sounds like it was running good..

Jason

 

[turbofabricator]

When is the knock occuring? It may be false knock caused by down-pipe hitting frame or some other component. Do you have a torque strap? If so, have you checked the accessory bracket for loose bolts. Trans mount broken, engine mount broken, cracked flexplate, loose torque converter bolts, bowling ball rolling around in trunk
You could be experiencing pre-ignition, not detonation. Both will cause knock. Do you have a good understanding on how to read spark plugs to look for pre-ignition? Pre-ignition is usually caused by a hot spot in the combustion space. Pre-ignition will usually KILL an engine faster than detonation though. It will melt a hole in the piston crown, so I suspect pre-ignition isn't the problem, especially with alcohol cooling things down in the combustion chamber.
You might also be having an injector problem, in that one may be clogging up on you and not flowing correctly. The computer will over compensate the other injectors to try and enrichen the bad cylinder, causing higher O2 readings. One cylinder then can be detonating but still have high O2's.