heavy knocking w/ 93 octane [Archive] - GrandAmGT.com Forum
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ttah8
10-01-2006, 06:08 PM
The last 3 gas tanks have been V-Power 93 octane and my car still knocks and pings when I turn it off. I added Valvoline SynPower Fuel Injector Cleaner at my last oil change about 1000 miles ago, and I use Valvoline SynPower Full Synthetic Oil. I made the switch to higher octane gas to help with the knocking, but it doesnt seem like its doing much? what should i do?
ihatemygrandamg
10-01-2006, 06:36 PM
Ive been running 93 for a while now cause of my mms pcm. Maybe try a can of seafoam
tjc13
10-01-2006, 09:05 PM
The last 3 gas tanks have been V-Power 93 octane and my car still knocks and pings when I turn it off. I added Valvoline SynPower Fuel Injector Cleaner at my last oil change about 1000 miles ago, and I use Valvoline SynPower Full Synthetic Oil. I made the switch to higher octane gas to help with the knocking, but it doesnt seem like its doing much? what should i do?

Are you talking about the motor or the hot exhaust system?
CoopGT
10-01-2006, 10:18 PM
He's talking about the sound the exhaust makes as its cooling down. LOL

Dude 93 octane fuel isn't going to do anything for that. That sound your hearing is normal as it cools off.

Someone else can explain engine knock here . But engine knock happens under moderate to hard acceleration( sorry sp).
ttah8
10-01-2006, 10:29 PM
i see...man, do i feel like a horse's petut. i just always get out of my car and hear it from the engine, so thought it was going on under the hood, well...it is. but it sounds like you guys say its normal!
ihatemygrandamg
10-01-2006, 10:43 PM
I get out of my car and hear my cooling fans still running. Thanks pcm! :)
lone_wolf025
10-01-2006, 10:55 PM
i see...man, do i feel like a horse's petut. i just always get out of my car and hear it from the engine, so thought it was going on under the hood, well...it is. but it sounds like you guys say its normal!

It does happen under the hood. What happens is that due to the rapid cooling of the motor once its shut off the exhaust manifolds rapidly contract. The sudden contraction sends shockwaves through the metal and it clangs when the energy disperses on impact with something like the aluminum heat shields of the headers. Try wacking around with a hammer handle and you'll eventually wind up finding the same sound.

Engine knock is basically abnormal combustion occuring inside the chamber. It only happens under certain conditions like excessively lean or rich mixtures, too much carbon buildup causing a hotspot, excessive compression, etc. Basically you'll always need 3 things for it to happen: Heat/Compression, fuel, and air. If the engine is off all you got is heat and no fuel and therefore no knock. When it happens, instead of a typical combustion happening in .003 second (three-thousandths of a second) it occurs in about .001-.0015 ish seconds. The resulting shockwave that it produces causes the knocking sound.
AaronGTR
10-02-2006, 09:09 AM
Yeah, that sound isn't knocking. Knocking happens while the engine is running. And if you don't have a tuned computer running high octane isn't going to help at all. Usually if someone has a stock pcm and is getting a little detonation in hot weather, a switch to 89 octane will solve it. If you're still getting knock after that there's probably something else wrong with the engine. Apparently all you're hearing though is the pinging sound of the exhaust cooling down.
LoboMan7409
10-02-2006, 12:18 PM
HUH, I thought that sound was the oil dripping back into the pan
harvester45
10-02-2006, 01:40 PM
HUH, I thought that sound was the oil dripping back into the pan

That's what I always thought, too. :confused:
coupe
10-02-2006, 02:02 PM
You guys thought it was oil dripping back into the pan?.....wow
lone_wolf025
10-02-2006, 03:01 PM
One should only hope its not the oil going back into the pan. If that were the case you'd have much worse to worry about...:)
SikMindz
10-02-2006, 03:09 PM
Apparently today the All Go section has become the Newbie Introduction forum...if you guys really want to do something wild you should open your hood after driving and spray it with a hose. Listen to that!

Joking...joking....
LoboMan7409
10-02-2006, 05:16 PM
You guys thought it was oil dripping back into the pan?.....wow

Wow, some of you guys with years on this site forget that some of us use it as a learning tool, thanks for making me feel dumb.
Ajaxus
10-02-2006, 05:27 PM
ahhh, reminds me of when i was new. don't worry, we all make our fair share of dumb comments. :)


and some people will forever make those comments *cough*stacy*cough*
harvester45
10-02-2006, 05:29 PM
Yeah, I thought it was the oil cooling down/returning to the pan, I never even thought it would be related to the exhaust. I'm kinda a newb, too.
Grand_am_power
10-02-2006, 06:53 PM
:) Lol
coupe
10-03-2006, 05:45 AM
Wow, some of you guys with years on this site forget that some of us use it as a learning tool, thanks for making me feel dumb.


Sorry, didnt realize this was the first motor vehicle you have ever owned.
Sprucegagt
10-03-2006, 08:04 AM
HUH, I thought that sound was the oil dripping back into the pan

That's what I always thought, too.:confused:

:nono:

What's really sad is neither one of you are really newbs.
digitalballz
10-03-2006, 06:13 PM
And to think I thought it was the injectors still firing to help cool the motor down... who would have thought........ lol !!!!!!!!!!!
LoboMan7409
10-03-2006, 06:28 PM
Sorry, didnt realize this was the first motor vehicle you have ever owned.

Well how about we discuss the theory of conservation of matter, or what your stand on the United States should be allowed to decide who has WMD's or not, or why Einsteins theory of relativity works. You know cars, good for you, if you want me to make you feel like a dumbass then lets talk physics or politics.
SikMindz
10-03-2006, 06:32 PM
Loboman- calm down or I'm going to have the mod of this section start handing out points. He said his piece and apologized more or less- there's no need to provoke anything further.
LoboMan7409
10-03-2006, 06:43 PM
Loboman- calm down or I'm going to have the mod of this section start handing out points. He said his piece and apologized more or less- there's no need to provoke anything further.

I am sorry but I do not consider "sorry I didnt realize that this was your first car" an appology.
SpyhunteR
10-03-2006, 07:04 PM
tra lalala, we're on a car forum, in the performance section, and people are insulted when they realize that what they thought isn't what it seemed and as a matter of fact is wrong. People poke fun, they whine and retort that they're smarter than car guy in everything else.

COOL IT MAGAZINE/INTERWEB MECHANICS!
phoenixad
10-22-2006, 07:07 PM
Has anyone checked there blinker fluid yet? It gets low sometimes!
coupe
10-23-2006, 06:41 AM
I appologize Lobo, my bad.