Diagnose My Exhaust Issue(s)...I'll even provide some clues (1 Viewer)

[Gnarwgn]

Ok team, I have exhaust issues, need your help/pointers to figure out how to pursue the solution. Here is the history and clues:

* History - 2001 stock exhaust, 230k miles. Replaced muffler only within the past 10k miles with a Magnaflow after original muffler caved in. I thought that was the fix. Improved noise issues only.

Currently experiencing the following (clues):

1. Noticeable loss of power - this started around the time the original muffler failed, and did not improve upon install of new muffler.
2. Increased exhaust smell - nothing specific, but I believe this suggests additional exhaust leaks somewhere.
3. Acceleration - in an overdrive situation (like an onramp) - alot of additional noise coming from the right/passenger side of the vehicle. Combination of a high pitched whistle/squeal/screeching noise.

I should add - there is no memorable 'event' that would have triggered these issues. Appreciate any suggested solutions!

 

[hickuptruck]

Get a new maf sensor

 

[Mike NXP]

A lot of noise, like this recent post?
>>Please Help.. Loud noise while accelerating - https://forum.ih8mud.com/threads/please-help-loud-noise-while-accelerating.1296493/


Without thinking too hard I would guess loud exhaust noises are caused by exhaust leaks or clogged air flow along the way. MAF sensor may have to do with loss of performance but it shouldn't make your exhaust any louder.

 

[J1000]

Ok team, I have exhaust issues, need your help/pointers to figure out how to pursue the solution. Here is the history and clues:

* History - 2001 stock exhaust, 230k miles. Replaced muffler only within the past 10k miles with a Magnaflow after original muffler caved in. I thought that was the fix. Improved noise issues only.

Currently experiencing the following (clues):

1. Noticeable loss of power - this started around the time the original muffler failed, and did not improve upon install of new muffler.
2. Increased exhaust smell - nothing specific, but I believe this suggests additional exhaust leaks somewhere.
3. Acceleration - in an overdrive situation (like an onramp) - alot of additional noise coming from the right/passenger side of the vehicle. Combination of a high pitched whistle/squeal/screeching noise.

I should add - there is no memorable 'event' that would have triggered these issues. Appreciate any suggested solutions!

100% clogged/melted catalytic converter.

 

[4Beast]

100% clogged/melted catalytic converter.

Wouldn't that throw a CEL?

 

[J1000]

Wouldn't that throw a CEL?

Sometimes yes, mostly no. ECU doesn't really have a way to know. Hissing from exhaust and big loss of power two big clues.

I don't know what it is but I've diagnosed so many melted cats in the past two years on friends and familys and my own cars. Either it's just a coincidence with age or something is going on with fuel blends. If the cats don't get stolen they melt.

 

[nissanh]

Hint before you do new cats: park your LC out of your garage, let the thieves to do their job to make your life easy on installation. Also place a thankyou note for them!

 

[2001LC]

IMHO you would get a CEL in 2001 with a clogged CAT. Since down stream O2 sensor, is rear of CAT. So it is not where I'd start looking. But I would circle back to CAT after more common issue covered.

A number of issues may be going on. That will not through a CEL.

We need to consider. Sound is one sensory input, we use. With hole in muffler, accelerating vehicle sound fast. Muffler replaced, sound changes. So we now hear sound(s) that were there.

A clogged exhaust from bad CAT or other object in the pipes. Will not suddenly start with replacing muffler. Unless installer somehow clogged the pipe. Any clog from muffler install, would clog both banks of exhaust. Not just BK2 (PS). A walk around test would be to feel, if exhaust blowing out tail pipe. But to be sure you can have exhaust back pressure test done. Not so much a DIY project. Since gauge, hose and adapter will cost as much as paying a shop.

I'd first look at engine:

We get tick from 2 main issues (there are less common). Walk around inspection of tick. Put ear to LH frt fender well than RH, on cold start up. Do you hear a loud tick. One side or both. Does tick go away after warm-up or sound reduce. A tick that does not go away after warm-up, is a bad one. The most concerning here is spark plug walking out.

1) Spark plug walking out, resulting in combustion gasses blowing by its threads. This needs correcting ASAP, or head will be damaged.​

Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...

forum.ih8mud.com

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2) Exhaust manifold leak. A new muffler, may increase back pressure just a tad (maybe 0.5 PSI). Not really enough to increase leak. But new muffler (quieter) will make tick of leak at header more noticeable.The exhaust manifold crack is well document in mud.​

I'd also like to know the engine coolant temp (ECT) and fuel trims. Likely a good coolant service and tune-up in the cards.

Other engine sound are very often the drive belt and or it's bearings. This is also checked and corrected in a tune.-up.

A hissing after muffler install. Is often flange gasket(s) a Y pipe. Or weld of aftermarket cut & weld install.

 

[J1000]

It's a cat or both guaranteed. Ticking exhaust headers let fresh air into exhaust and that overheats the cat. A clogged cat turns every part of the exhaust into a hissing leak. Just dealt with this Saturday.

Dropping the cats shouldn't be too hard as long as it's not rusty. Take it for a spin and you'll know immediately.

 

[Gnarwgn]

Greatly appreciate all the insights and subsequent homework - I'll get to work as soon as I'm able and report back findings. @hamad974 sounds like you might need to do similar homework based on your post.

 

[hamad974]

Hint before you do new cats: park your LC out of your garage, let the thieves to do their job to make your life easy on installation. Also place a thankyou note for them!

Dang i should've done that before replacing my CATS smh

 

[hamad974]

Greatly appreciate all the insights and subsequent homework - I'll get to work as soon as I'm able and report back findings. @hamad974 sounds like you might need to do similar homework based on your post.

I appreciate that tag ... Im going to need to test the manifold to see if there is any mini cracks ... Its just not make any sense to me especially after replacing the CAT