2004 5.3 Exhaust popping/burbling on deleceration

[huminski]

Hi,

Just wondering if this is normal or not, I have a Gibson super truck exhaust installed and when slowing down, especially with a trailer, I get a lot of popping and burbling from the exhaust. Any way to stop this?

[jeverett]

Probably go back to factory, or install some resonators maybe, if possible?. Mine does it also, especially if I've been at a high rate of speed. It's just the truck using the engine's compression to help w/deceleration. I personally think it sounds cool, to a certain extent of course.

[Jimmiz71]

A couple weeks ago I put on a Cat-back 20 series Flowmaster system on my 99'Z71, to my suprise when I opened the package there was a large resonator in the box, my other truck, 79' Custom Deluxe has glass packs and makes that same popping noise, I agree with Jeverett I would pick up a Resonator, -Jimmy

[huminski]

Will a resonator make my pipes quieter? Because I don't want that. I'm already deliberating swapping out the gibson can with a 40-series flowmaster. I guess I'll just live with it as long as it's not a mechanical problem...

[Jimmiz71]

A Resonator will quiet your truck down a bit, I would leave it be.. I agree with Jayson that it sounds pretty cool. I chose the 20 series for my truck because I had heard the 40 was too quiet. but theres only one way to find out. Post a Thread asking for advise on which flowmaster sounds better, it all depends on your Cat, Headers ect...

[jeverett]

Isn't the 20 series a single chamber? I'd love to have some of those.

[Jimmiz71]

yup... now you guys have me wondering what mine would sound like without the resonator???

[jeverett]

If you take it off, tell me. Although my 40 series is plenty loud, im a sucker for a good sound

[grollins]

It's a fuel mixture problem. When you open up your engine and allow more airflow, your fuel mixture becomes too lean. You need to change your fuel mixture to match the air flow. If you keep driving it like that, you may overheat your exhaust valves.

[LoneWolf3]

Grollins, I put the K&N filter in, 70 series FM's on new '04, took to dealer to get computer reset/retune, whatever you want to call, and they would not do anything, they said no of this voided warranty and did not need an adjustment, they said it's fine as is, I was willing to pay for it so I'm feeling confident it's ok.

[v10_viper]

Originally Posted by grollins

It's a fuel mixture problem. When you open up your engine and allow more airflow, your fuel mixture becomes too lean. You need to change your fuel mixture to match the air flow. If you keep driving it like that, you may overheat your exhaust valves.

Maybe with an intake but i dont think a freer flowing exhaust would, besides I have a 92 with a 350, stock manifolds then it's straight pipe, no cat or muffler or anything, it's been this way for a long time and no problem. Crackles like a mofo when decelerating in third and overdrive if i've been going over 70-80 mph and i just let off the gas. It's no problem at all, sounds absolutely lovely. Anyways with todays engines with all the sensors there are, dont you think they might compensate for the added air and add more fuel maybe??

[huminski]

I always heard this sound out of some cars at the drag strip after they cross the line and let off the gas, and was told by a few people it was a too lean air/fuel mixture, so grollins kind of makes sense as it'k what I suspected it was. Can you do anything to the fuel mixture or curve with a hypertech?

[jeverett]

I don't think so. I looked in my Hypertech and couldn't find it. All of my friends who have put pipes on their trucks have the same sound. I just always thought it was normal after you added a meaner sounding muffler.

[grollins]

Just for giggles try replacing your o2 sensor. It could be your only problem. I'm not trying to be a smartass, but all your friends are running too lean also. Try pulling a couple spark plugs. They should be medium gray in color. If they are more toward white, it's another sign. Also if you noticed the engine running a bit hotter than it used to, it's another. I have been dealing with too lean conditions all my life. It is even more pronounced in smaller engines. My Harley EFI had to be completely remapped after I trashed the EPA air filter and put on some real pipes. Backfire and decel popping was the norm until the fuel mixture was enriched. The lean condition is also the biggest reason for blued pipes. If the bike is running properly, they will not blue. My pipes are perfect. I think your dealer tech has been around too many stock factory trucks.
Good luck Bro!

[trey_dogg3]

I have a 40 and nothing else and I beleve it is loud as hell. And I love it.