# Experiencing detonation.....



## johnebgoode (Oct 4, 2005)

Last nite I had my buddy, who works for a Chevy Dealership, program a new key for me so I can use a remote starter, he owns his own Tech II. Anyway, I offered to let him take it for a spin. When I told him to punch it,(motor wasn't cold), he and I both heard what we feel is detonation,(popping thru the exhaust under acceleration). Has anyone else had this problem?. I am using premium gas (Mobil or Shell).


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## MarineGTO (Aug 24, 2005)

If you have it in nuetral and over rev it does it make the same sound?
(i know I am an idiot)


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## johnebgoode (Oct 4, 2005)

MarineGTO said:


> If you have it in nuetral and over rev it does it make the same sound?
> (i know I am an idiot)


never tried that.................


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## Juniorss (Nov 10, 2005)

MarineGTO said:


> If you have it in nuetral and over rev it does it make the same sound?
> (i know I am an idiot)


You can't over rev it in neutral I don't think. It would bounce off the limiter.


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## EEZ GOAT (Jul 9, 2005)

:agree


Juniorss said:


> You can't over rev it in neutral I don't think. It would bounce off the limiter.


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## Guest (Dec 20, 2005)

cant overrev in anygear LMFAO.. it will bounce off the limiter when burning out and in neutral.. and under load it will bog the hell out yo car... :willy: arty:


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## ShAkz05GTO (Dec 9, 2005)

Vedli said:


> cant overrev in anygear LMFAO.. it will bounce off the limiter when burning out and in neutral.. and under load it will bog the hell out yo car... :willy: arty:


You can overrev it if you are in 6th, and drop it to 2nd or something. :lol:


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## Guest (Dec 20, 2005)

ShAkz05GTO said:


> You can overrev it if you are in 6th, and drop it to 2nd or something. :lol:


ya and unload all your work related stress on your tranny LOL... :willy: arty:


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## GNX231 (Dec 12, 2004)

detonation is not heard through the exhuast (tail pipes that is) but under the hood. it sound as if one of the pistons is loose and rattling that chances are you won't even hear it becuase the computer will retard the timming so fast if you do hear it it will only be for a second or two.


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## dealernut (Oct 22, 2005)

Most of the guys that lease their cars here(about 5 of them) use regular gas and they hear those noises when the engine is cold. 

Might just have a tank of badly mixed gas.


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## baron_iv (Nov 17, 2005)

Detonation sounds like a can of spray paint with metal balls inside. It's more prevalent at WOT. 
Many people describe the sound in different ways.
I bet what you're hearing is the natural "cackling" of the exhaust when you let off the gas. Which is at the opposite time that detonation happens (when you are ON the gas).
If you don't have a supercharged/turbocharged engine, the chances that you're getting detonation are VERY VERY slim. The computer is designed to prevent that. GNX was right, the computer would be pulling timing so quickly that you'd never even be able to hear the detonation. 
I'll bet'cha dollars to donuts that you're hearing something else. If you want to double-check, you can always go on down to your local tuner/dyno-shop, and have him put an O2 sensor on your exhaust (or inside your tailpipe), then get a good tune. It's worth the money anyway. You'll pick up a couple of extra horsepower, and your worries about detonation can be relieved. 
Until you can get the tune, if you're worried that it is detonation (despite my EXPERT opinion that it's not haha), use premium fuel and don't go WOT if you can help it. 
Whenever you figure out what it is, please post back here, I'm interested to know what you find out.


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## Guest (Dec 20, 2005)

we all are interested when a user has a problem and gets it diagnosed.


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## baron_iv (Nov 17, 2005)

Yep, it's very important that you post back, that way if anyone else runs into the same problem, they can see what you did to resolve it. 

Also, bad gas won't cause detonation. It'll cause your car to run like crap, but I *SERIOUSLY* doubt that you'll ever hear any detonation. That computer works SO quickly that it'll yank timing before your brain can diagnose, cross-reference and process the sound.


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## Guest (Dec 20, 2005)

computers are nice!


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## baron_iv (Nov 17, 2005)

Well, it sure beats getting out of the car and turning those dang screws on the carburetor every time the temperature changes a couple of degrees! :lol:


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## Guest (Dec 20, 2005)

carbs suck! gotta let em warm up. with computers, you just turn key, and by the time you buckled your seat belt, you can go!


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> Detonation sounds like a can of spray paint with metal balls inside. It's more prevalent at WOT.
> Many people describe the sound in different ways.
> I bet what you're hearing is the natural "cackling" of the exhaust when you let off the gas. Which is at the opposite time that detonation happens (when you are ON the gas).
> If you don't have a supercharged/turbocharged engine, the chances that you're getting detonation are VERY VERY slim. The computer is designed to prevent that. GNX was right, the computer would be pulling timing so quickly that you'd never even be able to hear the detonation.
> ...


Thanks for the input. The noise is definately coming from the exhaust under acceleration only....(scratches head). It sounds tinny, and I'm only using premium gas Mobil or Exxon or Shell. Depends where I am when I'm low on fuel. Could it possibly be the restrictions in the pipes from the factory where they crimp it for clearance? These areas are crimped severely.


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## Guest (Dec 20, 2005)

have you checked the plugs?


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## johnebgoode (Oct 4, 2005)

big_mike said:


> have you checked the plugs?


With 1300 miles on it..........no


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## Guest (Dec 20, 2005)

never know........worse things have been found wrong on new cars. Just pull em to see what they look like. Maybe one has a broken electrode.


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## johnebgoode (Oct 4, 2005)

big_mike said:


> never know........worse things have been found wrong on new cars. Just pull em to see what they look like. Maybe one has a broken electrode.


If electrode was broken I would think I would have an issue more often than just under power. I really dont wanna start wrenchin on this thing. I might as well have kept the Stang then................. :lol:


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## Guest (Dec 20, 2005)

MUFFLER BEARINGS ARE OUT!!!!!!!!!!!!!! :willy:


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## baron_iv (Nov 17, 2005)

Generally, if an electrode is broken, you'll notice...mainly because you'll be running on 7 cylinders. 
A Tinny sound from the exhaust...hmm. What have you changed as far as exhaust goes? Different muffler(s), headers, catback? What have you done to the intake? K&N FIPK? Changing the intake can certainly make the exhaust sound different.
The crimping on the exhaust shouldn't make any noises. It will limit exhaust flow overall, but it shouldn't SOUND any different than it always has.


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> Generally, if an electrode is broken, you'll notice...mainly because you'll be running on 7 cylinders.
> A Tinny sound from the exhaust...hmm. What have you changed as far as exhaust goes? Different muffler(s), headers, catback? What have you done to the intake? K&N FIPK? Changing the intake can certainly make the exhaust sound different.
> The crimping on the exhaust shouldn't make any noises. It will limit exhaust flow overall, but it shouldn't SOUND any different than it always has.


Stock exhaust with SAP Mufflers and tips. K&N intake system. Other than this car is all stock


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## baron_iv (Nov 17, 2005)

Popping while accelerating throws me off. Adding the K&N would add to the "cackling" sound when you let OFF the gas. 
I'd say just to have it dyno tuned, and take it easy on the car until then. That's probably your best course of action. I don't think it's detonation, but I'm not entirely sure what it IS either. The computer is designed to retard timing when detonation is detected, which is what leads me to the conclusion that it's not likely to be detonation. However, I can't completely rule it out at this time. Detonation WILL destroy your engine (or more likely burn through a piston), so it's not something to mess around with. I just haven't heard of that problem very often on a naturally aspirated engine, and never on a modern, computer-controlled engine that is naturally aspirated. 
You could check for trouble codes using the dash computer by holding menu and set as you turn on the key. I kinda doubt that it'll tell you anything, but it never hurts to check.
Did you remove the wire from the negative side of the battery whenever you installed the K&N? If not, it's possible that your computer didn't recognize it, and you could be running a bit lean...which *may* cause detonation for a moment, but the computer should "fix" itself in short order. If you didn't unplug it, go ahead and do that...unplug it for about 30 minutes. 
My recommendation is a dyno tune with an O2 sensor to rule out the detonation issue. It's a pretty expensive "fix", but it comes with a lot of benefits too.


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> Popping while accelerating throws me off. Adding the K&N would add to the "cackling" sound when you let OFF the gas.
> I'd say just to have it dyno tuned, and take it easy on the car until then. That's probably your best course of action. I don't think it's detonation, but I'm not entirely sure what it IS either. The computer is designed to retard timing when detonation is detected, which is what leads me to the conclusion that it's not likely to be detonation. However, I can't completely rule it out at this time. Detonation WILL destroy your engine (or more likely burn through a piston), so it's not something to mess around with. I just haven't heard of that problem very often on a naturally aspirated engine, and never on a modern, computer-controlled engine that is naturally aspirated.
> You could check for trouble codes using the dash computer by holding menu and set as you turn on the key. I kinda doubt that it'll tell you anything, but it never hurts to check.
> Did you remove the wire from the negative side of the battery whenever you installed the K&N? If not, it's possible that your computer didn't recognize it, and you could be running a bit lean...which *may* cause detonation for a moment, but the computer should "fix" itself in short order. If you didn't unplug it, go ahead and do that...unplug it for about 30 minutes.
> My recommendation is a dyno tune with an O2 sensor to rule out the detonation issue. It's a pretty expensive "fix", but it comes with a lot of benefits too.


I'll try the battery disconnect and see what happens. As far a tune, I really want to stay away from that only because I dont wanna start playing with this thing. Wanna keep it Stock , if possible. Will let ya know what happens. Doin it right now.


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## baron_iv (Nov 17, 2005)

Actually, a tune isn't bad for the car. They're tuned VERY conservatively from the factory. If you have an automatic, it can also adjust your shift points and firmness to make it shift considerably better. Torque Management can also be turned off. 
I suppose you could do damage to the car if you had someone tune it who didn't know what they were doing. You can ask around here for people who know how to tune and I'm sure you can get a lot of great suggestions. If you ARE seeing detonation, and the computer ISN'T removing the timing, tuning may be your ONLY option (other than replacing the PCM altogether...which would probably be covered under warranty). If you're near Missouri, I can give you a name or two of people you can trust to tune it properly. If you don't want to go that route, you can always take it to the dealership, they can listen to it and probably do a much better job of diagnosing the problem than I can, since I can't physcially hear the car or see other symptoms.
Then again, this could all just be your exhaust getting "broken in" and it could be nothing to worry about at all. 
After you re-attach the negative cable to the battery, it might take a few miles for the car to get back to "normal". I don't know exactly how fast these cars re-learn, but I'm sure someone here does.


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## Guest (Dec 20, 2005)

10-15 miles of driving the car re-learns. And a tune is not deriving it from stock, its just fixing certain problems.


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> Actually, a tune isn't bad for the car. They're tuned VERY conservatively from the factory. If you have an automatic, it can also adjust your shift points and firmness to make it shift considerably better. Torque Management can also be turned off.
> I suppose you could do damage to the car if you had someone tune it who didn't know what they were doing. You can ask around here for people who know how to tune and I'm sure you can get a lot of great suggestions. If you ARE seeing detonation, and the computer ISN'T removing the timing, tuning may be your ONLY option (other than replacing the PCM altogether...which would probably be covered under warranty). If you're near Missouri, I can give you a name or two of people you can trust to tune it properly. If you don't want to go that route, you can always take it to the dealership, they can listen to it and probably do a much better job of diagnosing the problem than I can, since I can't physcially hear the car or see other symptoms.
> Then again, this could all just be your exhaust getting "broken in" and it could be nothing to worry about at all.
> After you re-attach the negative cable to the battery, it might take a few miles for the car to get back to "normal". I don't know exactly how fast these cars re-learn, but I'm sure someone here does.


Problem is it's an itermittent problem.


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## Guest (Dec 20, 2005)

I got the perfect solution for ya.

www.autotap.com


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## baron_iv (Nov 17, 2005)

If it's an intermittent problem, it's almost certainly not detonation. If the computer wasn't working properly to retard timing, it would be that way all the time, not just occasionally. Severe temperature changes could cause detonation, but we're talking 70+ degrees of changes in a VERY short time. 
I am really baffled now.


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## Guest (Dec 20, 2005)

I still think the AutoTap software would work best. If the computer sees something, you can too. Then you can tell the dealer what the problem is and even provide a read-out.


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> If it's an intermittent problem, it's almost certainly not detonation. If the computer wasn't working properly to retard timing, it would be that way all the time, not just occasionally. Severe temperature changes could cause detonation, but we're talking 70+ degrees of changes in a VERY short time.
> I am really baffled now.


That makes 2 of us................ :confused


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## Guest (Dec 20, 2005)

wait, it just hit me..... lets assume your running a little rich and fuel is sitting in the exhaust. That popping you hear could be that fuel igniting in the exhaust.

yeah?


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## Guest (Dec 20, 2005)

and thats what made the muffler bearings go out


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## Guest (Dec 20, 2005)

maybe he should have greased them then huh? lol


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## Guest (Dec 20, 2005)

better check the blinker fluid


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## Guest (Dec 20, 2005)

no no, the problem is obvious. Its a muffler filter that went out.










A new one is $45, problem solved !!!


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## Guest (Dec 20, 2005)

O-BOY If heard it all now


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## Guest (Dec 20, 2005)

oh no you havent, check this place out.

http://www.kalecoauto.com/


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## LITTLE GTO (Dec 8, 2005)

I always heard that the K&N air filter leans out the motor a little bit. Try putting your stock airfilter and box on and see if the noise goes away.


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## Guest (Dec 20, 2005)

its worth a shot.


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## baron_iv (Nov 17, 2005)

Considering how conservative the stock tune is, it's very unlikely that the K&N could make it SO lean that you get detonation. Sure it might lean it up a bit...temporarily, but then the computer will react, notice it's lean and adjust.
I really just don't know about this problem. It's gotta be something odd, something that I haven't had to deal with yet. It certainly doesn't SOUND like anything I've heard of before.


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## johnebgoode (Oct 4, 2005)

It seems to have become an issue only since weather got very cold. Sounds like marbles in the tail pipes


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## baron_iv (Nov 17, 2005)

That's EXACTLY the opposite of detonation. You would be more likely to get detonation in HOT weather. Cool weather prevents detonation, since the air charge going into your engine is much cooler, therefore more dense.
I'm going to say that I'm 99.7% sure that it's NOT detonation now. 
You don't think that maybe somebody slipped some rocks or something into your tailpipe(s) do you? Maybe as a joke or something? I'm not sure what it would sound like, or if that's even POSSIBLE, but ya just never know these days.


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> That's EXACTLY the opposite of detonation. You would be more likely to get detonation in HOT weather. Cool weather prevents detonation, since the air charge going into your engine is much cooler, therefore more dense.
> I'm going to say that I'm 99.7% sure that it's NOT detonation now.
> You don't think that maybe somebody slipped some rocks or something into your tailpipe(s) do you? Maybe as a joke or something? I'm not sure what it would sound like, or if that's even POSSIBLE, but ya just never know these days.


Highly doubtful. Car goes no where. Only has 1300 miles on it since 10/07/05.It's in my sight all day long at work. 25' away from me.


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## baron_iv (Nov 17, 2005)

Very very odd.
Do you think you could get an audio clip of it for us? 

You can feel relieved now, it's almost certainly not detonation. I just really don't know what it is though.


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## Guest (Dec 21, 2005)

same here, but would have a better idea if I could hear it.


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## edysinger (Nov 23, 2005)

First, have you tried disabling the remote starter and seeing if the problem goes away? My first impression since the remote starter has to enable fuel and spark with the key off, the remote starter is not working correctly and interefering with the engine's timing (incorrect timing can create exhaust popping).
Second, possibly an exhaust leak created by the cold?
Third, lean injector affected by the cold.
Fourth and long shot, bad exhaust valve.

In any case, if your buddy has a Tech II, he should be able to view misfire counters to see if the engine is affected and also the spark advance. Also, look at the LTM's and STM's when the problem happens to see if lean fueling is occuring.

Hope this helps you out.


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## Guest (Dec 21, 2005)

damn, I used to know what those stood for:

LTM - long term map?
STM - short term map?

its the fuel management right?


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## johnebgoode (Oct 4, 2005)

edysinger said:


> First, have you tried disabling the remote starter and seeing if the problem goes away? My first impression since the remote starter has to enable fuel and spark with the key off, the remote starter is not working correctly and interefering with the engine's timing (incorrect timing can create exhaust popping).
> Second, possibly an exhaust leak created by the cold?
> Third, lean injector affected by the cold.
> Fourth and long shot, bad exhaust valve.
> ...


Remote starter isn't in yet.


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## johnebgoode (Oct 4, 2005)

baron_iv said:


> Very very odd.
> Do you think you could get an audio clip of it for us?
> 
> You can feel relieved now, it's almost certainly not detonation. I just really don't know what it is though.


Don't have the capability to do that.


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## Guest (Dec 21, 2005)

still need to get a computer on it, while your driving, so it can pick it up. Needs to have a running log also, which is why I suggested AutoTap software.


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## johnebgoode (Oct 4, 2005)

big_mike said:


> still need to get a computer on it, while your driving, so it can pick it up. Needs to have a running log also, which is why I suggested AutoTap software.


I'll see what my buddy can do for me. (The guy with the Tech II).


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## Guest (Dec 21, 2005)

alrighty! let us know...


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