Ok so i take college classes for mechanics and for the past couple of years my truck has been acting like it has no ***** whatsoever when it comes to WOT. So this morning we pulled it in and done a electronic compression test on it and all of the cylinders read fine except for one but it was about 78% compression and the teacher said that thats not enough to make a big difference in power. So then we hooked a scan tool up to it and there were no codes. Now, about a month ago i put true duals on my truck(no cats and glasspacks.) Power wise i didnt notice anything. I have noticed though since i have changed the exhaust that if it sits and idles for a little while then it will suddenly start running VERY rich and start idling VERY VERY rough to the point that you cant even hear it but its still barely running. And while the scan tool was hooked up to it today it started doing the idling thing and the teacher freaked out. So i mentioned that to the teacher and he gave me a weird look and asked how many 02 sensors i had and i told him 2 in one pipe. He then sighed really big and said that the reason for it idling rough is because the side of the motor that has the pipe with no 02 sensors doesnt know whats going on and he said a bunch of other stuff that i dont remember but anyways, does anybody have a point on this on what i could do? He said that adding o2 sensors wont help it and that the only way it would fix it is that if i switched the exhaust over completely. I wanted to cry. lol And also before i had a D.I. S.O. high flow cat and a cherry bomb extreme and it didnt have power then so the pipes arent the power problem.

 

Do you have literal true duals? Or is there an h or x pipe in there somewhere. Because if so I'm pretty sure you can put the o2 in there, or something like that

 

Having the o2's in one pipe is fine, its not an 8000 HP drag motor. The O2's are likely bad because of plenum gasket.

 

yes, I have ATRUE duals. Lol

 

Pretty sure the OEM exhaust has both sensors on 1 pipe..

 

+1.
as long as the engine is in good condition, and one side is not different from the other (as in fuel injector malfunction) or intake leak on only one side, then letting the pcm monitor one side is ok.

just as an experiment, disconnect your O2 sensors and let it run in open loop mode and see if it acts any different. it'll set a code for no O2 (ignore that) and it'll run with its default fuel tables. it should run fine. if it spits and sputters the same way, you have something else wrong.

 

The fuel trim on that engine isn't reliant on TWO specific banks, so leave your duals where they are. BUT, if you have a mechanical problem affecting combustion on the bank that doesn't have the O2 sensors on it, you won't see the symptoms as clearly on the scan tool data, if at all.

I assume you have cats on both sides (or no side) , correct?
Run compression AGAIN especially on the "no sensor" side to make sure. Otherwise I would be inclined to agree with Zman about the plenum bellypan gasket as a very good possiblity. Don't forget to compare spark plugs to one another. Compare plug to plug overall AND right 4 to left 4. They can tell you all sorts of tales. If you have cheap O2 sensors, get rid of them and get good ones.

 

I have no cats. And okay i will compare plugs. A guy i work with said that the fuel filter could be a possibility??

 

Okay everybody keeps saying that the plenum gasket is bad. Its $300+ to get replaced and i would do it myself but i dont have the time. So if i got it replaced and it didnt fix it, i would be very mad. lol

 

Forums are a DIY oasis...generally. Nobody here really advocates that you go out and pay retail to get your car worked on, especially if you're in a Tech School. These are all mere suggestions from all of us based on the information that YOU put out there. We have no first hand information of your symptoms, data, etc. If you want to minimize and/or eliminate the risks involved, then go to a reputable shop and pay a diagnostic fee. Expecting a 100% diagnosis from people who have no access to your car is unrealistic. We are just trying to point you in the right direction so you can arrive at it on your own. That's all anyone here can do.