This was a while back but I figured I would ask now since its really been bothering me lately. A couple of months ago I got the "wait4me performance" tune and installed a magnaflow (dual 3"in to a single 4"out) muffler with a 4" tailpipe. A few weeks ago my truck started smelling like rotten eggs, and the truck lost power. The idle was high (about 800-900rpm). Then one day it sounded like a shotgun went off, the idle dropped to normal, and the smell went away. I figured the cat was getting clogged and finally blew out. Since then the truck still doesnt have quite the same kick it used too. I thought I noticed the performance drop after putting the exhaust on, but it kept getting worse. I know its not just psychological b/c it takes an effort to do a burnout now and it used to do it without asking:) . Sorry for the long post. Any ideas???

Well, if smelled bad, then it probably was running very fat. Raw fuel could have built up in your converters and then got hot enough to ignite. It that is the case, your converters are probably melted down inside and causing restriction. You could remove them and clean them out and put them back on and see if that helps. Could have a lame O2 sensor. That should throw a code though. That is where I would start.

Thanks for the tips. That was one of the things I was thinking of (inspecting the cats) but I thought I would see if there were any other tips only b/c its a pain to hack the exhaust and weld it back together.

I have a nice new cam for the truck but I dont wanna put it in until I figure out what the problem is. I was talking to a friend about fixing the exhaust problem and he said the answer was sitting right in my truck on the passenger seat (the cam):rolleyes:

jbone---

Good Morning---:)

Mr. Goodwrench can check the flow of your exhaust
with out hacking and cutting. They do it with pressure
gages using the O2 sensor opening and vs. the tailpipe
outlet. There is a back-pressure limit and if you exceed
it--you lose power.

Steady Eddie
L-21 454 Vortec

How have you eliminated the tune you put in?

Stop putting Diesel fuel in it! :D

All kidding aside I would put a scan tool on it just to check history since you don't have a check engine light at the moment.

Sounds to me like the tune was putting in too much gas. That gas ignited in the cats and boom. Just like Duromax04 said. Did you have the tune done as if you had that new cam installed?

I am no tuner by any means, but I would assume the tune to be different with a stock cam or a modified cam. If you tuned it for the modified cam, but ran the stock cam, I could see excess gas being introduced when it shouldn't of been.

The cam hasnt been installed yet (and Im debating even doing it at all. Comp has been giving me the run around on what is/isnt needed for the swap):rolleyes:

The tune is for the exact set up on my truck as it sits. And I dont believe it has been eliminated.

Another thing I forgot to mention is I hear these trucks are very sensitive to backpressure drops. Could the size of the muffler/pipe be affecting it??

Another thing I forgot to mention is I hear these trucks are very sensitive to backpressure drops. Could the size of the muffler/pipe be affecting it??

I have wondered that myself.

Just remove the O2 sensors and test drive it, if the power picks up you may have a blockage. Also any muffler shop can drill a tap and measure back pressure then weld it back up. We do it all the time when checking for clogged exhaust.

A back pressure drop shouldn't cause any problems.

Vernon

The only reason I mention back pressure is b/c I have heard a lot of guys that put larger exhausts on losing power right off the bat.

Listen carefully, with their low overlap stock cams losing power by reducing engine pumping losses such as lowering backpressure is physically impossible. Now they could have easily made a clogged fuel filter issue more apparent. Without adequate fuel, you're not going to loose power by adding more airflow.

The factory pipes are dual 3", sounds big to me. Why? Reduced temperature when towing heavy. Backpressure, just a necessary evil of a quite exhaust.

Vernon

Haven't had any problems with lowering backpressure on my truck. I actually ran straight pipe for about 5k with no issues other than decibal level. Currently running 3-inch glasspacks which flow pretty close to straight, just a tad quieter. When you increase airflow, the powerband of the motor moves up. Some feel that their trucks lose some low end power when adding an exhaust because it takes a hair longer to reach peak hp as its further up the RPM scale. Just my two cents, could be wrong.

You're probably exactly right, I never could understand that myth.

Vernon