Car detonating?
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 1,007
Likes: 2
Car detonating?
I had my car in for a dyno a few weeks back, and they said my car was detonating pretty bad. What does that mean and what should I do to fix it? Does that mean I need a new set of spark plugs? If so, which plugs do you guys recommend? Thanks in advance! 
edit: meant to post this in the C5 tech section, sorry mods.
edit: meant to post this in the C5 tech section, sorry mods.
Last edited by StealthZ06; Oct 31, 2006 at 08:18 PM.
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 1,007
Likes: 2
Originally Posted by Blindfingers
What grade of gas are you using?
Lower octane ratings lead to detonation and knocking.
Lower octane ratings lead to detonation and knocking.
I ONLY use Chevron 93 Octane. Would the detonation have anything to do with my spark plugs?
Burning Brakes
Joined: Apr 2006
Posts: 926
Likes: 12
From: Lutz FL
Originally Posted by StealthZ06
I had my car in for a dyno a few weeks back, and they said my car was detonating pretty bad. What does that mean and what should I do to fix it? Does that mean I need a new set of spark plugs? If so, which plugs do you guys recommend? Thanks in advance!
edit: meant to post this in the C5 tech section, sorry mods.
edit: meant to post this in the C5 tech section, sorry mods.
All this is usualy because the timing isn't set for the grade (octane) of fuel being used since various octanes detonate at different temperatures. If I remember right, higher octane fuels require advanced timing vs. lower octane fuel.
I could be wrong here, and someone else feel free to correct me, but that's what I remember...
Thread Starter
Burning Brakes
Joined: May 2002
Posts: 1,007
Likes: 2
Originally Posted by ericstanley
From what I remember from my automotive class in high school (17+ years ago), detonation (aka "ping", "knock" or "piston slap") occurs when the fuel in the chamber detonates just prior to spark, and then the spark itself causese a second explosion that results in what looks like a sonic wave in the piston head. The result is that the piston, when travelling backward after the initial detonation, moves from side to side and "slaps" the wall and damages both the block and the piston (of couse, you need a LOT of detonation before substantial damage occurs).
All this is usualy because the timing isn't set for the grade (octane) of fuel being used since various octanes detonate at different temperatures. If I remember right, higher octane fuels require advanced timing vs. lower octane fuel.
I could be wrong here, and someone else feel free to correct me, but that's what I remember...
All this is usualy because the timing isn't set for the grade (octane) of fuel being used since various octanes detonate at different temperatures. If I remember right, higher octane fuels require advanced timing vs. lower octane fuel.
I could be wrong here, and someone else feel free to correct me, but that's what I remember...
Thank you for your help!
Does that mean I need a tune?
Burning Brakes
Joined: Apr 2006
Posts: 926
Likes: 12
From: Lutz FL
Originally Posted by StealthZ06
Thank you for your help!
Does that mean I need a tune?
Does that mean I need a tune?
Likely, yes. If you're running 93 you shouldn't be detonating unless there is already some custom tune in it for even higher octane gas. Did you buy the car new or did you get it used? If you got it used you might want to consider taking it to a dealer and having them flash the system back to the stock program and see if that clears up the knock. Do you hear it knocking at WOT or are you going on their word only?
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Thread Starter
Burning Brakes
Joined: May 2002
Posts: 1,007
Likes: 2
Originally Posted by ericstanley
Likely, yes. If you're running 93 you shouldn't be detonating unless there is already some custom tune in it for even higher octane gas. Did you buy the car new or did you get it used? If you got it used you might want to consider taking it to a dealer and having them flash the system back to the stock program and see if that clears up the knock. Do you hear it knocking at WOT or are you going on their word only?
