Exhaust Sound under load

[Heloavi]

Only happens at a certain speed and gas pedal position. Sounds like heat shield but I can only replicate it at about 55mph when I am trying to maintain that speed. Muffler shop said they did not see anything loose but could be inside of muffler. They also said it sounds like I may have a small exhaust leak on passenger side but they do not mess with that far up. Only from flange back. Sounds like it is the CAT as it is right below my feet.

I did a search and found one person had a crack and another had a heat shield issue. Anyone else?

[Lizardmen3477]

Man you have alota issues haha. Check the bolts on the header heat shields or try to rev it in park an see if anything rattles

[Heloavi]

I know. Labor of love. I will check that. I have put it in park and rev but it does not sound like when it is driving.
Thanks

[hughesdt]

Did you check the big nut, 23mm I think, under the EGR? Its on the passengers side. I had mine come loose and could hear an exhaust leak when ever the engine was under a load.

I also had both flanges break at the pipe, but both where incredibly obvious something was wrong. Bad noise all the time.

I have only one time, on a different car, had a cat come apart. Started as a rattle in the muffler when ever I hit a bump. I could tell by shaking the muffler. But it eventually blocked the pipe and the car wouldn't do anything above an idle.

Good luck

Dan

[Heloavi]

So far I have found that I have one broken bolt on driver side heat shield. Not sure how I am going to fix that yet.

Next is to get a crows fut to check the EGR nut. Borrow one from Autozone I hope.

Will let you know if I find anything else.

[Heloavi]

Update. Checked the EGR nut. It is tight. So still think once I find a way to fix the heat shield I will be good to go.

[Heloavi]

Want to bring this back alive. Seems not to be EGR, Heat Shields or Muffler. Seems like an O2 sensor but I am not getting a code. Passenger side O2 rattles when I hit the pipe. I read on a Chevy thread the GM sensors housings come loose at the top. Just crimp them with a pair of pliers. Guess I will try that next.