I have a '94 F150 w/302. My truck has no muffler. I was out 4 wheeling, and I think I hit something pretty hard (rock). Anyway, when I started my truck the next morning, I heard something hit under my truck. I got out and found that I had little ceramic pieces all over the driveway under my truck. Now when I drive, it obviously sounds kinda crappy, but my biggest problem is after about 5 miles, the check engine light comes on and I hear a pinging like noise. Like when I slow down to go around a corner then accelerate again, it makes kind of a "dieseling" sound. I'm stumped, anyone got any suggestions?

 

Check the cat real good. You busted up the cat internals. You probably have a clogged cat.
zanny

 

You don't probably have a clogged cat, you definitely have no cat. You must have banged it so hard that you broke the ceramic substrate inside the catalytic converter. Go buy an aftermarket unit, there are enough of them out there. Don't pay extra for what some manufacturers call "High Flow" the ceramic substrate inside every aftermarket converter have 400 cells per square inch no matter how big the inlet/outlet the internal cells only allow so much exhaust to pass through. There is a new converter on Ebay with 300 cell per sq inch made by Eastern Catalytic that actually does give more flow. Search for "Eastern Catalytic Converter". If you don't believe me about the 400 cell per square inch substrate call any converter manufacturer and ask before you buy. With a new converter the check engine light should reset but if not you may need a mechanic to clear the computer codes. The pinging noise is most likely just the damaged converter.

 

i also have a 302 and i removed the muffler and it gave me a nice sound. i got a new end pipe and one day when i was welding it up i got the idea to hollow out the 2nd cat (right before the muffler). i proceded to do so and it took me about 2 hours to get it completly hollowed out so now all i have is the first or pre-cat. i think it sounds great (really deep) and when im in a high gear like 4th or 5th it almost sounds like a diesel which i think is cool. it defeanitly turns heads and unfortunatly cops heads but iv gotten away with it every time. so what im saying is if you dont want to spent 200$ or more, just hollow it out.

 

Sometimes what happens is with no muffler, cold water can run down the exhaust pipe, hit the hot converter, and crack the honeycomb.

 

Well, I hollowed out my second cat to see if it was the cat making the pinging noise, and I think it was, because I haven't heard the noise since. However, now my truck sounds like a damn tractor. It's a little too loud for my taste. Maybe not so much the volume, I guess, but the way it sounds. It just doesn't sound like a smooth mellow tone. I think I'm gonna spend the money and go with a high-flow and a good muffler.