Under certain throttle positions (10-30%) in any gear at any rpm, I can hear this knocking sound coming from the front of the car. Has anyone else experienced this? It is not a loud nor hard sounding knock. It sounds as almost if a fan is hitting a shroud or something like that. I figure'd i'd ask the real pros before i took it in for some warranty service.

 

I have kinda the same problem mine is like a rattling noise up front and it usually only happens at fairly slow speeds. I can hardly hear it when the windows are up but when there down you can hear it pretty good. Not trying to hijack the thread but the problem is similar.

 

its not pinging is it? you put good gas in it?

 

Regular 87. It's good gas, my sound is like some metallic rattling. It's very strange it's only under part throttle. Maybe I can't hear it when I get into the gas because of the engine noise I'm not sure.

 

you arent putting 87 octane fuel in an LS1 car are ya ??? You should only be using high octane fuel ! you can put 89 in there but it is not recommended , as you will be in low octane mode , even with 89 octane .

 

your hearing pinging noise and that is from detonation! when you put that low of an octane in the car it is gonna make those noises! put some 93 in it and you will be all right

 

I have the 5.3 truck I guess I should've said that earlier. I'll try to run 93 in it and see if that helps. It doesn't detonate under WOT. It doesn't sound like any pinging I've ever heard. The truck has 161k miles if that has anything to do with it.

 

thrawn dude you got your self some knocking going on there. so check the engine, look for oil build up in the intake, change the plugs do some basic maintenence if it dont go away then take it to a mechanic and have them check the timing.

 

My 99 Z28 just started doing something similar to this. I know mine is pinging. Whenever I give my car gas and the rpm's are very low, like when giving it gas after shifting to the next gear, it pings when I give it gas. It only does it under a load at low rpm's. I run 93 in mine already. The car has got 82k miles on it so I guess its time for atleast some plugs.

BTW the car has no mods.

Are you sure yours is not pinging?

 

sounds like detonation form the description. fix it. good luck trying to get the dealer to acknowlege it. unless the car throws codes it's all "normal" to those clowns

 

Is it a tapping noise?

 

I'm gonna run some 93 octane. My plugs have less than 10k miles on them and should still be very good. Maybe pinging but it sounds like rattling.

 

I always use 93 octane. The car is bone stock so if it's pinging from the factory.. GM! I've always heard the saying that if you can audibly hear the pinging, chances are the car's not driveable. I am 99% sure the car isn't detonating.

 

./bump

 

I had pinging(detonation, the sound is exactly the same you described) on a 100% stock car 93/96/92 octane only, lasted for almost half a year before I finally swapped a cat and that seems to have fixed it. If a car is bone stock it does not mean stuff will not go bad, like O2s, CATs, fuel filter, plugs/wires, etc.

If you don't believe it is detonating, hook up a scanner, go part throttle or whatever the condition is when you hear " the rattle" and look at your KR value. I bet it goes up, meaning knock sensors pick it up and PCM thinks it is detonation. Of course, it still may be something else tricking the PCM but chances are, this is a real detonation (again, based on your description)

 

Yea, i'll hook the mt2500 up to it tomorrow and see what it tells me