Causes of "Real" Knock?
11-28-2005, 02:06 PM
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Causes of "Real" Knock? I have posted and searched my knock retard problem (timing is about 17 degrees due to -4 KR and -10 low octane table). I think that it is probably false and so I am preparing to address possible sources of false knock but I need to look at possible sources of real knock as well (even though I cannot hear it).
Real knock can be caused by:
1) Bad/low octane gas (unlikely since the KR is present all the time).
2) PCV oil (there was no significant oil in my intake but I noticed that my PCV line was unhooked at the valve cover when I did my cam, it us hooked up now so I am going to install a catch can).
3) Carbon deposits (is it worth doing SeaFoam just in case - this does not seem like it would be good for the engine).
Anything else I can look at that could be causing real knock?
Thanks,
Steve
Real knock can be caused by:
1) Bad/low octane gas (unlikely since the KR is present all the time).
2) PCV oil (there was no significant oil in my intake but I noticed that my PCV line was unhooked at the valve cover when I did my cam, it us hooked up now so I am going to install a catch can).
3) Carbon deposits (is it worth doing SeaFoam just in case - this does not seem like it would be good for the engine).
Anything else I can look at that could be causing real knock?
Thanks,
Steve 
11-28-2005, 05:18 PM
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Yes, high octane is a great test! We had a knock problem once that 100 UL didn't touch; turned out a sparkplug was loose from the factory and overheated so much it turned into a glow plug! (Too high a heat range is the same issue.)
Other causes of 'real knock':
o- Overtorqued/oversensitive sensors reacting to trace levels.
o- Lean cylinder/cylinders due to restricted flow injectors.
o- Air pockets or other causes of localized overheating.
False knock:
o- Valve noise, piston slap, exhaust system grounding out under load. (One band aid fix is to under-torque sensors or wrap threads in teflon tape to reduce sensitivity.)
o- Defective knock sensor.
o- I'm sure there's more...
Other causes of 'real knock':
o- Overtorqued/oversensitive sensors reacting to trace levels.
o- Lean cylinder/cylinders due to restricted flow injectors.
o- Air pockets or other causes of localized overheating.
False knock:
o- Valve noise, piston slap, exhaust system grounding out under load. (One band aid fix is to under-torque sensors or wrap threads in teflon tape to reduce sensitivity.)
o- Defective knock sensor.
o- I'm sure there's more...
11-29-2005, 02:14 PM
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Launching!
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Thanks for the replies. I will probably work on most of the suggestions except maybe not the sensors themselves yet - I am getting no codes and I don't want to pull the intake if I can help it.
I just installed a 227/224 cam and found out about the KR during the tune. I don't know if it was there before the cam or not but, if not, it may explain the less-than-expected performance improvement (about 0.1 sec & 1 mph in the quarter and 361 HP on the dyno).
Where do I get SeaFoam?
Thanks,
Steve
I just installed a 227/224 cam and found out about the KR during the tune. I don't know if it was there before the cam or not but, if not, it may explain the less-than-expected performance improvement (about 0.1 sec & 1 mph in the quarter and 361 HP on the dyno).
Where do I get SeaFoam?
Thanks,
Steve 
