I just got my car back this past friday and as i was driving it home i noticed that if i stepped on the gas a little harder i hear a rattle-like sound coming from the engine bay. It starts at about 3-4k rpm's. At first i thought it was the inline fuel pump mounted on the firewall that was making all that damn noise, but i checked it out and it is fairly tight against the wall. I tried searching, but i keep getting a message that says "archived topics are disabled. I've read in the past that detonation has a pinging sound to it. But it's hard to tell wether or not your detonating when you've never heard it before. Right? I've only taking the car as for as 5k rpm's just to be on the safe side. What do you guys think it is?

(poormans turbo):
Inline fuel pump (drag III)
Vortech FMU
BCPR7ES plugs gapped at 30.
missing link
Deltagate Wastegate ( ) 7 pound spring.

 

Detonation sounds like small ball bearings or bb's being rattled in an empty coffee can. I you are hearing it, do some work. I hear that sound twice before I blew my old motor.

 

that is spark knock... detonation sounds liek the bottm end is about to fly all to ****

 

Never heard that from anyone before.

 

And what exactly does that sound like?
Thats about as descriptive as saying that detonation sounds like detonation....

 

i wasn't sure on the differences of the sound myself, but my auto-tech teacher assures me that the BB in a can sound is spark knock, and detonation is scary sounding

 

The BB sound sure scared the schitt out of me! How dangerous is spark knock and what does it do to the motor?

 

QUOTE: "...detonation sounds like the bottom end is about to fly all to ****"


I'm affraid now . Cause that's what it kinda sounds like. Another factor that i wasn't looking at was that my front motor mount is pretty much gone and my in CV boot is torn too. Also, i noticed a couple of times when it was making all that rattling noise, that if i went over a small bump in the road it would kinda stop for that split second. That's why i'm not sure if it's something rubbing or what....

 

Spark knock - Does that happen where there is a heavy load on the engine? (i.e. going up a hill in high gear at low rpm)

My car seems to make that sound when the car is warm and heavy load.

Not boosted yet though. Just worried what'll happen when boosted.

 

don't take me wrong, spark knock isn't a good thing either, and can casue serious problems as well if not taken care of... spark knock is usually a result of too much timing

 

I see. Thanks for the info!

 

anyone else?

 

wtf? spark knock?
detonation sounds like bb's in a coffee can, despite what your auto tech teacher told you.

 

spark knock and detoation are 2 different conditions caused by many variables

 

Never heard of spark knock, but...

Pinging, detonation, knocking, are all terms used to describe that rattling/clattering/bb sound, as Tony Stark stated, which is "officially" known as pre-detonation.

My Grandma's car was detonating for years because she put 87 octane in and it required a little better gas (to make up for the pos bowtie motor).

 

this isn't your basic high school auto tech, i am studying mechanics in college, and we are one of only 10 NATEF certified schools in my state

yes, there is a difference between spark knock and detonation, they are simialr, and spark knock is like a lesser form of detontation that isn't as violent as what is typically known as detonation

 

[QUOTE]Never heard of spark knock, but...

Pinging, detonation, knocking, are all terms used to describe that rattling/clattering/bb sound, as Tony Stark stated, which is "officially" known as pre-detonation.[QUOTE]

This dude hit the nail on the head. What you heard is bad and it can kill your motor. You either need to turn down the boost, add more fuel or retard your timing. The best thing to do is to drive your *** to a dyno and do some wide band pulls.

Dial it in before you are searching for another motor.

 

Sounds like pinging. You'll know it once you hear it.

 

EX-Boosted97Lude you have the right idea, but your terminology is confusing.


Detonation (pinging) is when the fuel mixture explodes, rather than burns.
Caused by: lean mixture, hot intake charge, bad gas, etc.

Preignition is the one you guys are missing. This is when the fuel mixture is ignited
too soon. The burning mixture starts to push the piston down before it even gets to the top of its stroke. This is usually caused by over advanced ignition timing, but having sharp edges on your pistons, or in the combustion chamber can create "hotspots" which will ignite the mixture early. Every time i hear someone say "sharp edges cause detonation" it makes me want to ****** kill somebody. PREIGNITION! not detonation! argh!

Anyhow, detonation is what sounds like "rattling BBs", etc.
Preignition sounds very different, it kinda sounds like you have an out of balance tire, and makes a "wump wump wump wump" sound. You can actually feel it through the floor if your motor mounts are stiff.

Detonation is the most violent of the two, and the explosive pressure will cause cracked ring lands, etc. Preignition is less harmful, but just imagine whats happening: your pistons are basically forced to compress an expanding mixture, which puts enormous strain on the rods and can possibly cause rod bearing contact.

I hope this clears a few things up for people!


[Modified by rioninja, 6:59 PM 3/31/2003]

 

ah, much better .preignition is the term I (and most) are familiar with.
i was like , wtf..spark knock..lol.
and I knew that detonation is the bb sound!


[Modified by SiRkid, 1:26 AM 4/1/2003]

 

Preignition is less harmful

False. Preignition is almost certain engine failure within seconds. You don't recover from preiginition. 9 times out of 10, preignition melts the a hole in the piston top. Another quick note that hasn't been pointed out...

Detonation always occurs AFTER the spark plug fires and starts burning the a/f.
Pre-ignition always occurs BEFORE the spark plug fires.

I'm not sure how far back the archives go but I wrote a detailed post on the differences a few months back....


[Modified by true, 2:48 AM 4/1/2003]

 

I've always heard "by the time you hear it, its too late." At least by the time you hear it quite a bit of damage is done which is why I was thinking of adding a Knock link when I boost. That way I can see any "pinging" before I can hear it.


Eric

 

By the time you hear it, there is some SERIOUS detonation happening.

 

First of all i would like to thank all the members that posted on this thread. All the information that was mentioned was VERY informative, not just for myself, but for all of us.


*** maybe this should be archived****

-Tech

 

I hear slight ticking sometimes at high rpms. Sounds almost like electricity sparking.