Exhaust noise question

86erstang · 12-02-2008, 03:36 PM

I just bought a 86 LX with a 3.8L. It has a small exhaust leak that I'm going to fix this weekend, but I don't think that will fix my problem. When I rev the motor the exhaust sounds fine, but when I let of the gas it makes a sound kinda like little backfires. Kinda like put put put. Does anyone know what might be causing this. I've put new filters, plugs, wires, and a new muffler on, if that helps. This is my first restoration so I'm new to alot of this type of stuff, so thanks for your help. Cory

Choppa · 12-02-2008, 11:44 PM

im not 100% sure but it might not have a smog pump or maybe a bad smog pump not sure wat it does but my trans am makes that noise when i let off the gas and i kno that doesnt have one i kinda like it but it is a 400 so its little deeper muscle sound not sure wat a 3.8 would sounds like

86erstang · 12-03-2008, 11:45 AM

It has a smog pump, and i think its good. I live in California and your car has to pass a smog test to be registered. It just passed three weeks ago, so I assume the smog pump is good. As for the sound, it sucks! It sounds like the car is a POS, but it seems to run great. But thanks for your help.

3.8YOU · 12-03-2008, 01:59 PM

rusted mufflers will make that noise

86erstang · 12-04-2008, 10:46 AM

I just put a new muffler on it. but exhaust to the muffler is pretty old? maybe thats it.

cobra232 · 12-04-2008, 11:12 AM

it's small amounts of unburned fuel igniting causing small backfires or popping. just about every car does it. some are more noticable than others. timing can be adjusted to reduce it or increase it if you want but you will never get rid of it. my car does it it's no big deal and nothing is wrong with your car

www.moranav6racing.com and www.supersixmotorsports.com both make performance stuff for your year mustang if you ever are interested in making more power

86erstang · 12-04-2008, 12:09 PM

thanks for the info i do want to upgrade and I NEED more power. First thing I got to do is get rid of the lame 3 speed AT thats in it!

86erstang · 12-05-2008, 07:07 PM

it doesn't sound like a normal running car, carb or not. it a loud sound that sounds like s**t. maybe it is the timing. does anyone know how I should change the timing? I've heard that advancing the timing gives a little extra kick. I'd like to try that but don't know how to do it. any help would be great!