hi i need help is it possible to have false knocking at only high speed i have tire a bit unbalance shaking a little bit can it be felt by knock sensors via alum driveshaft.. my timing back (add 5.47) near 81 and 106 mph
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false knocking on 3 and 4 gear
- Thread starter bob450
- Start date
What makes you think it's false knock? Have you done logs with high octane gas?
I have the same issue and I am struggling to find out what it is. High octane gas does not fix it.
Have you looked over your exhaust to make sure it's not contacting anything? I remember another post where it was simply an exhaust clamp tapping the body under acceleration giving false knock. If you think it's from an unbalanced tire then get that fixed. That should be a very easy fix and then test again.
False knock as in pulling timing and slowing the car down?
The knock sensors can pick up vibrations from other things on the car like exhaust contacting metal for example. The sensor thinks there is knock and pulls timing.
In this example the engine may have had zero knock but timing was still pulled. In other words "false knock"
If you are getting knock on say 91 octane and want to know if its bad gas or false knock you can run 100 octane and data log. If the knock is gone then it was bad 91 gas. If you still have knock then it may be something else getting picked up by the sensor.
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Then you have real knock?
I run E85 but had no clue a vibration could cause knock and pull timing?
Buddy of mine was getting knock in only 4th gear. So narrowed it down to a mph issue, turned out to be one of the front tires wasn't balanced correctly. So OP is only getting knock at higher speeds, it's most likely a balance issue in a tire. If it was gas it wouldn't only happens at higher speeds. Most likely same with exhaust.
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