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01-03-2010, 08:21 PM #1
Engine Knocking, don't know what to do
I have a 99 silverado 4.8L and it has brand new knock sensors and brand new oxygen sensors of the passenger side. After i replaced them ses light came on and said the O2 sensors weren't working, then the light went back off after a day. And i can here knocking in the engine, thought replacing the sensors would work since there was knocking before i replaced them and one of them was bad. Any thoughts on why its still knocking?1999 Silverado 4.8L V8 2WD
6" suspension lift by Fabtech
3" body lift
Toyo Mud Terrain 35" tires, 16" Weld Racing Rims
Magnaflow cat-back exhaust
K&N cold air intake
Hypertech Performance Programmer
Viper Security w/remote start
Kenwood Speakers, 2 12" Kicker Comps
Valor 7" flip out head unit
01-03-2010, 08:25 PM #2
Engine Knocking, dont know what to do
I see you have a Hypertech programmer. What tune are you runing, 87 or 93 octane?
01-04-2010, 12:20 AM #3
Whoa is it KNOCKING or pinging from detonation becuase knock sensors dont fix rod bearings
99 tahoe 2 dr. 4x4 7.4 4L80-e NP246, SAS, dana 60 hp, sterling 10.5 rear, gibson headers, and alot of tricks of the trade !!!!!!IF YOU'RE NOT CHEATING YOUR NOT TRYING!!!!!!!!
01-04-2010, 05:19 PM #4
I'm really not sure, i think its pinging, i just here this noise from the engine when I'm doing 40, and i gas it at about 2000rpms i can here it but its not very loud, used to be worse before i replaced the two sensors. And i run 89 all the time. I filled up about 20 miles ago with 91 premium. I was told i could have some water in the gas tank, and to put some rubbing alcohol in it?
01-04-2010, 11:19 PM #5
A predetonation will sound like a thump or clack and it will stumble along with various cylinders throughout the entire firing order. it is controlled by timing and exhuast gas mixing from egr. unless you have heavy carbon build up that is causing hot spots or the egr passages are starting to plug up the pcm should be able to tune it out but that engines kinda new for that stuff
01-04-2010, 11:45 PM #6
Its hard to describe, i mean its a not very loud and just sounds like something isn't working properly. I can only hear it at low rmp's, and im pretty sure it is pinging but i would think the computer could have stopped that by now. I went offroading and i noticed the noise that day, i'd say i did a good amount of bouncing around, is it possible something is out of place or a loose connection?
01-05-2010, 10:28 PM #7
Pretty sure its internal noise? not a motor mount that might be torqing just high enough to studder or a single exhuast leak that only comes on with load
01-06-2010, 01:02 AM #8
It almost sounds like squeaking. Before i replaced the knock sensors it was a lot louder and way worse. Now its just not very loud. Ill try to take a video or something and let you here the sound for yourself because you know more than i do. I'm pretty sure its pinging but I'm not positive.
01-06-2010, 01:09 AM #9
Oh and if it helps, going uphill it gets worse, you can really here it going up hill. But in order to here it i have to have the windows rolled up.
01-06-2010, 10:42 AM #10
Ya that sounds like a ping make sure the sensor is tight and dont use teflon tape or silicone it will act as a buffer and not let the knock sensor catch the slight detonations
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