A few months ago I had Pacesetter LT headers, Pacesetter Y-Pipe, Aero Turbine muffler, and a Magnaflow cat. put on my truck. All was fine for a week or two then the dreaded check engine light came on.... It's now been on for 2 months or so...forget the code #, but it's for cat efficiency. To make a long story somewhat short, my gas mileage has tanked and I was wondering if I could be using the "wrong" cat? I ordered the Magnaflow 94169 from Moe's and I should have realized from the time I received it, that it was about half the size of the stock cat. I've been searching around for other people having problems after doing LT's and haven't found anything related to what's happening to me. Any thoughts?

 

Do a search for Non-foulers and go from there. Thats whay guys use

 

My mileage got better, not a lot, but definitely better after putting on LT headers and I'm running the stock cats.

What O2 is setting off the CEL? If it's a post cat, it will not effect anything the PCM does, but if it's pre-cat it will. Could be it's got you running way to rich?

 

Metal, yes with a modified exhaust often you will get codes. The anti-foulers solve this problem. I spoke with Bob at Moe's today about this same. exhaust system. So what is your opinion of the system now that you have run it for a while? Also, we have a thread of our own for the 2003 model. The link is in my signature. Good luck...

 

Truck is definitely running rich (I can smell it) no idea why its running so rich either...Had the SC performance tune on it, but decided to put it back to stock in hopes it would lean it out. Didn't do anything, I can still smell gas all the time. I think I need to have the PCM reflashed, because my RPM's drop at idle, to around 500 and the truck starts to shake a little. Could this cause me to be running so rich possibly? As for how I like the setup...I love it! It sounds awesome!

 

I've got the pacesetter lt's with magnaflow high flow cats and pacesetter y pipe. After I installed the setup I started getting a code due to the high flow cats. Did the non-fouler trick back in January and haven't had a code since.

 

As Hammer pointed out the first O2 sensor inputs to the PCM "open loop" / "close Loop" It is pointing at that O2 sensor needs to be changed. Are you running single cat? What thermostat do have? Your PCM may be in a cold state, fattening the fuel system. Reboot PCM won't hurt. Good luck..

 

You need to put the SC performance tune back on, even though it may not solve your problem, the timing is pretty advanced which will lean you out a bit...

 

Yeah, I'm only running a single cat (that's all my truck had stock) and a 180 T-stat. About the O2 sensor being in a "loop"..I brought the truck to a buddy that hooked up his scan tool and was watching the sensors while the truck was running. Apparently they pass the test, but they are fluctuating up and down at almost the exact same times (I'm not very knowledgeable about O2 sensors). I'll try rebooting the PCM later today after work and see if that helps any.

 

Do you know what the code is that you are getting?