01 Sierra Denali

country_boy · September 21, 2009

I don't know if this should be under this section but my brother has a 2001 sierra denali. He took his muffler off the whole entire thing for 2 or 3 months and finally got one installed at a muffler shop. About a day after he got the muffler installed the truck started running bad after a oil change. He changed the spark plugs and it is running horrible. Sometime just stalling and takes awhile to get up to speed. Somebody has told us that their is a flap in the muffler that controls the flow so is this it or is it something else?

grayghost7 · September 21, 2009

I don't know if this should be under this section but my brother has a 2001 sierra denali. He took his muffler off the whole entire thing for 2 or 3 months and finally got one installed at a muffler shop. About a day after he got the muffler installed the truck started running bad after a oil change. He changed the spark plugs and it is running horrible. Sometime just stalling and takes awhile to get up to speed. Somebody has told us that their is a flap in the muffler that controls the flow so is this it or is it something else?

Sounds like it might be a plugged catalytic converter...that will hold you back considerably. Never heard of the muffler flap.

country_boy · September 21, 2009

Ok how will we know if it is the catalytic converter. and I don't know if they still put them on newer vehicles somebody just told us that they used to have them on mufflers on older vehicles.

WilliamBos · September 21, 2009

Ok how will we know if it is the catalytic converter. and I don't know if they still put them on newer vehicles somebody just told us that they used to have them on mufflers on older vehicles.

It has 2 cats, one on each side of the y-pipe. I am sure others will chime in on how to test them out.

Should find someone with a good scanner, like a Tech 2 to check the O2 sensors, could be one of the front sensors shot. (It has 4, 2 in front of Cat, and 2 behind.)

grayghost7 · September 21, 2009

Ok how will we know if it is the catalytic converter. and I don't know if they still put them on newer vehicles somebody just told us that they used to have them on mufflers on older vehicles.

It has 2 cats, one on each side of the y-pipe. I am sure others will chime in on how to test them out.

Should find someone with a good scanner, like a Tech 2 to check the O2 sensors, could be one of the front sensors shot. (It has 4, 2 in front of Cat, and 2 behind.)

Yep...all vehicles still have cats.

That brings up a question....if we have two cats, why aren't there dual exhaust pipes? Can we have duals legally?

country_boy · September 22, 2009

Ok this is truck is dual exhaust. Earlier today I was looking at it and put my hand under the mufflers and only the left had exhaust coming out of it. So we were taking it to the shop that put the muffler on it and bout 15 miles it wouldn't go no further, whatever we did it wouldn't move just sputter. Now the left muffler has water coming out and the right now has exhaust coming out. A friend hooked his scanner up to it and got P0420 googled it and brung up catalytis converter.

We talked to a mechanic and he said it could be the catalytis converter if the shop didn't put the right exhaust system on it or they didn't put a gasket on right and it got clogged in the muffler. If it is the catalytis converter could the shop be at fault?

grayghost7 · September 22, 2009

Ok this is truck is dual exhaust. Earlier today I was looking at it and put my hand under the mufflers and only the left had exhaust coming out of it. So we were taking it to the shop that put the muffler on it and bout 15 miles it wouldn't go no further, whatever we did it wouldn't move just sputter. Now the left muffler has water coming out and the right now has exhaust coming out. A friend hooked his scanner up to it and got P0420 googled it and brung up catalytis converter.

We talked to a mechanic and he said it could be the catalytis converter if the shop didn't put the right exhaust system on it or they didn't put a gasket on right and it got clogged in the muffler. If it is the catalytis converter could the shop be at fault?

I doubt it...they just clog up when they're done and you have to replace them.