Anybody know why my 3.9 sounds like its running inside a coffee can when I'm accelerating? I've changed all the standard things and finally got it running smooth, but it still sounds funny to me. Is it in the exhaust system or what?

 

Lol I'd imagine you'd be able to pinpoint a sound like that. What all have you changed? Usually a sound like that, during acceleration, I'd say yeah, its probably the muffler/exhaust broke, blown out, vibrating, or just shot so yeah, its loud.

 

Just got the truck a couple months ago. Changed all the filters (oil,air,fuel), both temp sensor and temp sending unit (which finally fixed the idle loping problem.), throttle position sensor, thermostat, and a few bulbs. It's not loud. just has that metallic "ring" to it. Don't know how else to explain it. I'm no mechanic by any means, but I'm not afraid to get my hands dirty to save a couple hundred bucks.

 

Sounds like a rattle or a shake or a pinging sound. Maybe some thing is loose or you got an exhaust leak or it is pinging which is due to pre-detonation which can be a common problem.

 

Try running a higher octane fuel. If you're running 87 go up to 91. If it goes away then it's preignition/detonation. What year is your truck? What is your fuel pressure at?

A.J.

 

I'll try that. It's a '93. I haven't checked the fuel pressure. I might get a chance to do that this weekend.

 

metallic ring sound can also be the stuff inside the catyletic converter rattling. mine does it but its nothing to be concearned with. if you live in a state that does emissions then you may have a problem when the put the tester in the tailpipe. for non emission states its no big deal

 

I see what ya mean and didn't think of pinging. I would check your exhaust and see if its loose ANYWHERE or if the muffler or cat rattle when you hit them but also still check your fuel pressure and try a higher octane like suggested just in case.