Thanks for your replies everyone!! So im guessing you dont think its the air/fuel mixture then?

 

I dont think it is the A/F ratio. It is a normal occurance for me only when cold and yes I have an aftermarket side exhaust. I kind of like it....all mean and nasty....I hear many exhaust that sound that way and i feel it is the nature of a modular 3V motor...... I read that equal length shortie headers or LT's will help smooth that out.... JMO but I would not worry.

 

+1 on startup and only when revved, when it comes back down, but hey I rermember Fox body cars doing it too back in the '80's, it seems to be a Mustang thing! LOL

 

mfk1988,

I noticed the last line of your post said you were thinking about tinkering with the A/F mixture yourself. I would avoid making those kind of changes yourself unless you are really experienced at tuning these cars.

 

I've noticed that when the engine is cold, the RPM's also drop nice and fast, as the engine is closing the throttle 100%. When it warms up after a minute or so, the RPM's drop twice as slow and the crackle/pop in exhaust is gone. I wonder what combination of factors is eliminating the crackle/pop and 100% throttle closure. I've heard it has something to do with emissions, and that is also why when you let off the throttle, it doesn't start decelerating right away either.. Kinda annoying.

 

I love that noise when mine starts up, I wish it did it longer than for the first few minutes. Im weird

 

It will sound like that until the fuel management system goes into closed loop mode.
Usually as soon as the O2 sensors come up to temp and start reading the exhaust gasses correctly for O2 content.

 

yeah BACKPRESSURE. your running bootubes and therefore no muffs and therfore no backprssure and the cracks and pops are gonna happen.

 

x pype would help but not without cats, muffs would help alot...............

 

my stock exhaust pops when i start it up, but i usually just wait until the rpms drop to 750 when idling then i go about my business.