Does your 5.3 do this?

[northcreek]

Sometimes when I turn the igniton switch to the on position I will hear a pop and it sounds like backfire at the intake,not real loud but still audible inside.Otherwise it runs fine,great mileage with no issues.
Anybody's 5.3 doing thisMike

 

[RayVoy]

I suspect you have a little fuel leak that is exploding as the engine starts.

Probably an injector leaking.

Try a bottle of injector, or top end, cleaner in the next tank of gas.

 

[RZAwora]

Mike,
I have an 06 with the same engine. I don't think mine makes this sound, as I haven't ever heard any kind of noise like what you are referring to. Good luck in finding the problem/fix. Rick

 

[n0kfb]

This almost sounds like what mine does, and has done, since new.

It is kind of a 'honk' that happens just as the engine initally fires. I don't hear this in normal warm-weather temperatures, and it is more pronounced when the temperature is below zero.

-- Dan Meyer

 

[northcreek]

I suspect you have a little fuel leak that is exploding as the engine starts.

Probably an injector leaking.

Try a bottle of injector, or top end, cleaner in the next tank of gas.

Ray, It's not when I start it,this happens when the switch is placed in the on position.As for cleaners,the manual is emphatic about not using injector cleaners or other fuel additives and I suspect that the Placebo effect is the thinking behind many of these "solutions in a can" fixes but that's just me and I appreciate your and other member comments.
I'll keep poking around and let you know if I find the cause of this gremlin...Mike.

 

[MDBT]

Nope.

 

[Wooluf1952]

Just a thought:

Are you sure it's coming from the engine compartment?

The doors for the HVAC, under the dash, might be making noise.

 

[RZAwora]

Just a thought:

Are you sure it's coming from the engine compartment?

The doors for the HVAC, under the dash, might be making noise.

I have had this sound before and would say this could be a high possibility of what you're hearing. It happens mainly when the HVAC is set on AUTO and the truck has been sitting awhile. It makes a little pop as the doors close to adjust for difference of operation from when the vehicle was parked.

northcreek- have you ever had someone stand outside to see if the noise is coming from outside? you have to remember our cabins are pretty sound-tight, so if you're hearing it inside, it would be pretty loud outside. I'm wondering if this may be the cause of your noise? I'd say test it out by always setting the HVAC to OFF when you park your truck and see if the noise goes away. GL

 

[STLtrailbSS]

I'm betting its the throttle body, on the ss before starting the truck i get a click its the butterfly valve "activating" little one second movement then the truck starts. After the remote start beeps you can hear it in this video we have identical set ups for tbs so that's my 2 cents

http://static.photobucket.com/player.swf?file=http://vid220.photobucket.com/albums/dd209/StlProject2007/VIDEO0033.mp4

 

[northcreek]

Well with the aid of my son's better ears, the pop that Iam hearing is coming from my OEM door speakers.This is with the radio/nav system off and the system has not been modified in any way.
It would seem that as the ignition system is energized it somehow powers the speakers,this occurs as you first enter the spring return portion ignition switch (or start).
I can live with this now since I know that it's not engine related....thanks for all of your suggestions and helpMike.

 

[Bartonmd]

Mine does not do this.

 

[RayVoy]

Turning off the radio does not turn off the speakers.

Along with the "radio" portion of the audio system, the Onstar and the chimes (for alerts) are always on when the key is turned on.

In fact, Onstar may work when the key is off.

The "key on" function actually wakes up the audio module (along with a lot of other modules), the power to the audio system is always hot.

The "pop" your hearing, is the system waking up.

 

[northcreek]

Turning off the radio does not turn off the speakers.

Along with the "radio" portion of the audio system, the Onstar and the chimes (for alerts) are always on when the key is turned on.

In fact, Onstar may work when the key is off.

The "key on" function actually wakes up the audio module (along with a lot of other modules), the power to the audio system is always hot.

The "pop" your hearing, is the system waking up.

Thanks Ray,that's good stuff to know and it makes perfect sense now,,Mike.

 

[lynch55]

Don't you just love it when you realize it's not the engine?:wootwoot: My 05 Silverado don't do that, but I have to change out the knock sensor as my check engine light is on and that's what my scanner told me. Why in the hell would you put a knock sensor under the damn intake? Oh I get it, it's so they can charge an exorbitant price for the fix!

 

[jimmyjam]

Don't you just love it when you realize it's not the engine?:wootwoot: My 05 Silverado don't do that, but I have to change out the knock sensor as my check engine light is on and that's what my scanner told me. Why in the hell would you put a knock sensor under the damn intake? Oh I get it, it's so they can charge an exorbitant price for the fix!

they moved to the bottom rear of the block the next year. removing the intake isn't too bad though

 

[RZAwora]

Glad you figured it out and it's nothing major.

 

[lynch55]

they moved to the bottom rear of the block the next year. removing the intake isn't too bad though

It's a pain in the arse though, it's been two of them done here in the last month by my son-in-law, he's a really good mechanic and very reasonable!

 

[northcreek]

Don't you just love it when you realize it's not the engine?:wootwoot: My 05 Silverado don't do that, but I have to change out the knock sensor as my check engine light is on and that's what my scanner told me. Why in the hell would you put a knock sensor under the damn intake? Oh I get it, it's so they can charge an exorbitant price for the fix!

they moved to the bottom rear of the block the next year. removing the intake isn't too bad though

Yes Iam very happy that it is not an engine problem,Iam not as familiar with the new generation GM V8s,I cut my teeth on the original SBC engines so the 5.3 is all new to me but,seems to be a worthy replacement for old small block.
My son changed several (under manifold)knock sensors on his old 5.3 and I'm glad that they changed the position of them.True that it isn't the worst job but,seems unnecessary given that they originally (on the SBC) were on the outsides on the block....Mike.

 

[lynch55]

Could not have said it better!

 

[fiberop1]

there is a snap, pop however u want to call it when I turn my key on. It's the fuel pump. Deadhead system right? Heard it since new.. 2006

 

[McGMT]

Well with the aid of my son's better ears, the pop that Iam hearing is coming from my OEM door speakers.This is with the radio/nav system off and the system has not been modified in any way.
It would seem that as the ignition system is energized it somehow powers the speakers,this occurs as you first enter the spring return portion ignition switch (or start).
I can live with this now since I know that it's not engine related....thanks for all of your suggestions and helpMike.

There is a bulletin about this pop sound... Lemme find it real quick and ill post it for ya...

Well of course it wont let me print it and I am not on my PC to do a screenshot BUT its bulletin# 06-08-44-021B Just says the usual, "this is a normal operating characteristic of the vehicle, no repairs are necessary." And that if you just rapidly start with no pause between it won't do it, "This is caused by a drop in voltage yadda yadda I aint typin it all out cuz it doesn't matter anyways hahah

 

[northcreek]

There is a bulletin about this pop sound... Lemme find it real quick and ill post it for ya...

Well of course it wont let me print it and I am not on my PC to do a screenshot BUT its bulletin# 06-08-44-021B Just says the usual, "this is a normal operating characteristic of the vehicle, no repairs are necessary." And that if you just rapidly start with no pause between it won't do it, "This is caused by a drop in voltage yadda yadda I aint typin it all out cuz it doesn't matter anyways hahah

Thanks,I'll look that up...Mike.

 

[BuckeyeEvan]

Just for the record I have this backfire popping noise and I am pretty sure it's not the speaker. I hear it better with the window down and with my head out the window. If I start and stop it a few times in a row it will go away. in my spare time I will try to record it and post it here.
Does vbulletin have BBcode for mp3?

 

[McGMT]

Just for the record I have this backfire popping noise and I am pretty sure it's not the speaker. I hear it better with the window down and with my head out the window. If I start and stop it a few times in a row it will go away. in my spare time I will try to record it and post it here.
Does vbulletin have BBcode for mp3?

Yea, the bulletin is only when you turn the key on without the engine started.. Yours is a whole different can-o-worms

 

[Jkust]

Have had three of the 5.3's and haven't experienced this.

 

[northcreek]

There is a bulletin about this pop sound... Lemme find it real quick and ill post it for ya...

Well of course it wont let me print it and I am not on my PC to do a screenshot BUT its bulletin# 06-08-44-021B Just says the usual, "this is a normal operating characteristic of the vehicle, no repairs are necessary." And that if you just rapidly start with no pause between it won't do it, "This is caused by a drop in voltage yadda yadda I aint typin it all out cuz it doesn't matter anyways hahah

Can you post a link to where you read the TSB? I cannot find a site that doesn't want $$ to view it....Mike.

 

[McGMT]

Can you post a link to where you read the TSB? I cannot find a site that doesn't want $$ to view it....Mike.

I can't ... I have a login to be able to see the ones for my vehicles, sorry... Most of the TSB's for the GMTs are the same for all the makes and models so the ones that I have access to for my TB are good for almost all GMT's

If I coulda` I woulda...