I have been noticing that my truck seems to be producing less power, on and off the nitrous which I have been running for over a year now. About 6 months ago I started to notice what sounded like a lifter tapping. Now I notice that the exhaust sounds week and raspy, not smooth and bellowly like the flo masters used to and just sounds awful like I got an exhaust leak when underneath the truck is able to echo off of a street curb or the car next to me. The engine is also surging mildy between 4000-5500rpm with what sound like light knock up high and you can feel it loose power when it surges..this is on and off of the nitrous. As of right now I am not going to tear the motor down to try and fix the problem if it is something major besides it is barley noticable. I will however be tearing it down as a project when I get the 6 liter swapped in which will be in 3 moths so if it it I will find out. Any one want to try and guess what it is, if anything at all? FYI I dont monitor my air fuel so could have been running lean on the nitrous all this time and not know it.

 

Any guesses?, If it were something major wouldnt it throw a code and check engine light?

 

maybe you do have an exhaust leak? you check all of that already? I dont think an exhaust leak would throw any codes... unless it effects the o2's

 

the only thing that i can think of that would not throw a code right away would be the cats slowly closing up, at first it would be nothing because not much would be cloged.
but over time with little by little slowly closing up exhaust pressure would slowly build chokeing the motor with a restricted flow out.
if it is the cats it should sound a little diffrent too, the diffrence can be so slight over time you would not notice it because you drive it every day.

 

 

Check your spark plugs too..

 

i am with u on this a little i have been seating here juggling this one,and u say it is not picking up any knock,what kind of fuel r u running.has the truck made any crasy sounds before this.how long has it been since u change u'r fuel filter.

 

I had a v6 camaro that i really beat on, always running 1st and 2nd to the rev limiter, and I went through 3 sets of stock cats before the dealer turned me away. Under low rpm it would act fine, but when I got into it it would feel like somting was holding it back, and the exhaust did sound weird. If you can weld cut a hole before the cats and see if it runs better. If you get an *** load of gain or any **** comes out you know the cats are bad.

 

I think Pappy may be on to it. Don't have to cut any holes. There is a back-pressure tester which I have used that screws into an o2 sensor bung. You rev to 3k a couple of times and check the pressure. Two pounds or less is ok, more is a problem. If you have dual exhaust, check both sides. When I broke my cat (nitrous sneeze), it wouldn't rev over 4k and measured 10 lbs back-pressure. It also made that blocked exhaust sound. The problem can also be in the muffler and can be intermittant if a broken part is moving around. You may be able to borrow the tester from a retail shop like Kragen or a muffler repair shop. By the way, SES codes are mostly for smog and don't always appear with problems. P.S. If it does prove into the exhaust. I believe it's considered part of smog equipment and is warranted to 100k mi.

 

Thanks everyone for your replies so far, sorry I haven’t checked in often as I like, I have been busy finishing up some school work...back to school after being out for 15 years really sucks . Any ways I see that a majority of you seem to think that the problem may primarily exist with the exhaust system. I was thinking more like progressive engine damage from running the nitrous for over a year now, but I’m a pessimist and always think the worst. Spark plugs have looked fine over the last 2 changes; I changed them twice in the last year to be safe, and will do it again in a few days. Truck has 80,000 on it now, and it will be around 3 months before the 6l swap, so maybe Ill take it somewhere and have the tests done just out of curiosity