I installed aftermarket exhaust with 3" pipes, an airaid intakes system and reprogrammed my computer with the hypertech power programmer 3 to improve performance. While driving down the highway I accelerated hard and heard a loud bang underneath my truck, which it turns out was the entire exhaust being blown off the y-pipe and out of the hangers. all the clamps are still tightened all the way down, including the one connecting everything to the y-pipe so its not a question of the hardware being too loose. Outside of that I can't figure out what could have caused this to happen. Any ideas?

 

Trying not to laugh...mmm......MMMmmmwhaahaahaahaaha! I swear I couldn't help it. J/K. I'm not sure what to tell you except, did you cram anything into the exhaust while you were installing it and forgot about it? Like a rag or something?

 

Something could have hit it, knocking it loose.

Not normal behavior for an exhaust, especially if the clamps are still tight.

It either got physically dislodged, or is clogged and pressure blew it off as Peacemanker says.

 

Back in the old carburetor days, I saw engines dump a large amount of fuel into the intake, and the super rich mixture was ignited by the hot exhaust or really late timing to produce an explosion powerful enough to blow a muffler off. But on these trucks I don't know.
You weren't driving in Iraq or someplace were you?

PS Welcome to the site! It can be fun here. If someone has a clue how that happened, I'm sure you'll find out. We don't always crack wise or just state the obvious.

 

I'm with Desperado on this one. If your truck backfired into the exhaust for any reason it could cause what you are describing.

 

If your truck passed enough raw fuel into the exhaust to ignite, I would imagine that you'd get a code, since even a simple misfire will light it up...?

But yeah, carb-ed engines can run this risk. It happened to a 1972 Country Squire wagon my folks had - wouldn't start one day, mom kept cranking it while pumping the throttle then BAM!