No o2's, no cat's , no muffler's = destroying the valve's. (there is no scavenging or back pressure what so ever) And what is this "performance chip" you are talking about? Brand name for instance. And the reason the exhaust was removed is because the cat was clogged as a result of the plenum being shot.

 

Yep. That why I was saying...fix what is know to be bad (or missing) and start from there! Too many issues going on here!

 

Not to be contrary, but if he's got at least six feet of pipe the valves are not in danger. The truck was hacked up by some kind of hillbilly, obviously, but the valves are safe. Unless, of course, the plenum gasket or valve guide seals are gone...

To the OP: All of these guys advising you to get the oxygen sensors into the pipe are steering you right. The thing will run like crap until you do that, and nothing else you might do will change that. Get at least the upstream sensor in there or there's no point asking any more questions.

The shuddering in overdrive is almost certainly due to one or more cylinders misfiring. I'd bet a quarter that the #8 spark plug is oil fouling... if it is, come on back with that data point and everyone here will tell you why and what you've got to look forward to.

 

Folks, I'm not a mechanic. The $1200 did include rebuilding the engine. As far as the chip, my son bought it with the understanding that he could "trick" the computer into operating without O2's. We put new 35" tires on the Dodge, sold the swampers.
Where should I locate the O2's? Can I drill and tap in the straight pipe?
The realilty of combat is starting to sneak up on him,

 

Someone lied to him. But it's a relatively cheap fix.

Have an exhaust shop weld a bung into the pipe, right in the neighborhood of just ahead of where the pipe runs near the transmission pan. You've got to get the upstream (or "pre-cat") sensor into the pipe, for sure. You can probably just hang the downstream sensor somewhere out of harm's way and get away with it.

Yeah, that'll happen. My kid came back from Ashtrayistan in January... now it's his excuse for being stupid, drunk, and aggressive. That's why he doesn't come around -- he knows if he pulled that crap here his highly trained, combat experienced butt would get kicked up and down the mountain by a long-haired old man. I hope your kid does better with it.

 

took me a good while to clear the fog out of my head when I got home.. it's hard to access if it's truly fog, or if it's imagined fog, or somewhere in between... anyway:

chip? no o2's? wow... and that dude calls himself a mechanic?
there is no way under the sun that these engines can run without management.. the management is based primarily off of sensors- and in closed loop, the o2 sensors are the primary point of data collection.. I bet he's washing the cylinders to the point it barely runs, but more to the point- there is zero ability to accurately observe/troubleshoot it without all the sensors providing some data..

where are you located?

 

I'm in South Central Indiana. And the service you all provide is outstanding. Thanks to all.