Engine Knock Under Load I Think.....
Thread Starter
Racer
Joined: Mar 2006
Posts: 270
Likes: 0
From: los altos ca
Engine Knock Under Load I Think.....
This problem is on a 02 C5, with 50,000 miles. The car has been sitting for about a month, so i went to give the Ls1 some exercise. When i noticed under heavy load there came a knocking sound. The sound can be described as a light rattle. The noise seems to only come under heavy load, at any rpm. I wish i could say but am not sure if its from the engine or tranny.
Current Mods: Corsa X pipe/exhaust
Blackwing
Nology plugs/wires
Ported throttle
180 thermostate
I however did not have the engine tuned. My main question is should i take it to a mechanic or tuner? Is this just a timing issue, or is there anything else that might be the cause of this noise? Any help is always apreciated
Current Mods: Corsa X pipe/exhaust
Blackwing
Nology plugs/wires
Ported throttle
180 thermostate
I however did not have the engine tuned. My main question is should i take it to a mechanic or tuner? Is this just a timing issue, or is there anything else that might be the cause of this noise? Any help is always apreciated
Le Mans Master
Joined: Nov 2002
Posts: 7,179
Likes: 2
From: Charlotte, NC
Does it run smooth with just a noise or is it missfireing?
What grade of gas did you run in it last?
How is the oil pressure??
Was this problem happening right after the mods or after the car sat for a long time??
I would say take it to a mechanic you need to know where the noise is coming from and what is causing it. A tuner can help you dial it in for performance...
-=Rick
What grade of gas did you run in it last?
How is the oil pressure??
Was this problem happening right after the mods or after the car sat for a long time??
I would say take it to a mechanic you need to know where the noise is coming from and what is causing it. A tuner can help you dial it in for performance...
-=Rick
Thread Starter
Racer
Joined: Mar 2006
Posts: 270
Likes: 0
From: los altos ca
Thanks for your reply....It seems to just be a noise no missfire...after the mods the car ran fine...good oil pressure as well...as for the gas I thought it might have gone bad as well, and refilled always with 91. Yet the problem still persists...
Team Owner
Joined: Mar 2001
Posts: 21,325
Likes: 3,841
From: small town in S.E Pa. PA
St. Jude Donor '03-'04
Your mods have no effect on this issue.
You either have bad gas
too low of octane
or Carbon build up...
Carbon Buiild up is common and requires the GM decarbonization process.. ( GM top end engine cleaner or Seafoam )
You either have bad gas
too low of octane
or Carbon build up...
Carbon Buiild up is common and requires the GM decarbonization process.. ( GM top end engine cleaner or Seafoam )
Race Director
Joined: Apr 2001
Posts: 19,329
Likes: 15
From: Saint Augustine, FL
Mid-TN Events Coordinator
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Originally Posted by Evil-Twin
Your mods have no effect on this issue.
You either have bad gas
too low of octane
or Carbon build up...
Carbon Buiild up is common and requires the GM decarbonization process.. ( GM top end engine cleaner or Seafoam )
You either have bad gas
too low of octane
or Carbon build up...
Carbon Buiild up is common and requires the GM decarbonization process.. ( GM top end engine cleaner or Seafoam )
How old is the gas in the car? We know it's at least a month old. I'd say burn the tank off, and fill up with some good gas. FWIW, I had NO knock until Monday of this week when I filled up at the Exxon down the street from my office. Funny thing is, I had benn scanning my car that day both to and from work. I could tell exactly when it started pinging...it was when I stopped to fill up.
Pro
Joined: Oct 2004
Posts: 514
Likes: 2
Originally Posted by JR_VETTE
How old is the gas in the car? We know it's at least a month old. I'd say burn the tank off, and fill up with some good gas. FWIW, I had NO knock until Monday of this week when I filled up at the Exxon down the street from my office. Funny thing is, I had benn scanning my car that day both to and from work. I could tell exactly when it started pinging...it was when I stopped to fill up.
Melting Slicks
Joined: Nov 2004
Posts: 3,424
Likes: 0
From: Las Vegas Nevada
St. Jude Donor '07-'08
Had the same problem with my vette when it was stock. Did alot of city driving so i just figured it was carboned up. When i had some mod work done and had it dynoed it did the same thing. But it wasn't detonation so i was relieved. I would take it out and just drive the **** out of it and the pinging would go away. Finally decided to add some Torco (octane additive) after going F/I and the problem disappeared.
Last edited by PUREFUN; Sep 30, 2006 at 11:35 PM.
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