Oka, so yestrday afternoon I cut off my muffler because, all the welds had rusted and broke, causing it to rattle at idle, and give me bad MPGs, I have another muffler to put on, i had cut it after the Cat Converter. So it goes Headers-Piping-cat- with a little bit of piping after the cat. And its without a muffler for a bit.

My Question was, will not having a muffler on. cause The Exhaust to have to little back pressure and throw my Valves out of adjustment? And suck up Air Into my exhaust?

Before my muffler had worn out, I was averaging around 15 MPGs in the city and 17-18 on the freeway. now after Im averaging around 11 in the City and 14 on the freeway.

 

How long has it been since you replaced the O2 sensor?

I'm betting the lack of muffler has more to do with the sensor not being able to read properly than the muffler being gone. Also, you won't burn a valve with THAT much pipe located after the header. It's gotta be HELLA loud in the cab, though!

 

I havent ever replaced one since I bought the truck. I guess I'll try that but wouldnt a faulty O2 Sensor Through an Engine Code causing the check Engine light to come on?

 

And yea it is really loud.

 

Not normally. they go bad over time & shoot your fuel economy into the crapper. I'd start ther for certain.

 

You can get an OEM Denso from www.sparkplugs.com. That or NGK is the only way to go.

 

I've got no muffler and a half-empty cat(pulled half the guts out). I get over 20 mpg no problem, 23 when I'm trying. My 02 sensor works just fine too BTW. Opening up the exhaust won't cause poor performance, or hurt the valves in any way. If anything it would cool them more. Because like you said, you've just lowered the backpressure and allowed the heated exhaust gasses to escape more efficiently. Lowering backpressure is always a good thing performance wise. I don't care what anybody says to the contrary. That's why drag racers run cutouts or straight pipes. More power off the line, more power at the end of the line.

PS, if you're running headers with the stock cat and muffler, you've wasted some serious cash on them. They're not likely doing you any good whatsoever.

 

Yeaa I have NGK G power Plugs, and NGK ignition wires that I replaced 3K ago, so most likely an O2 Sensor. thats why Im getting 10-11 MPGs, and its really startin to tick me off a little bit Lol.

 

Wow. 20-23 MPGs? on a 3.0? Lol I havnt ever had anything relatively close to that lol. and no Im not runnin headers YET lol. its all stock exhaust. (for now). So it wouldnt burn my valves. check, and it wont through them out of alignment, right?