Aya

I've searched all over multiple Mustang forums for the past three months and can't find an answer.

I have a 2003 GT Automatic with 21,300 miles on her. The only thing done to her so far is the American Muscle CAI and a 93octane performance tune.

When the car shifts at about 45-50MPH if I get on the gas to accelerate I can hear a rattling/fluttering noise. It will get louder if I hit the accelerator harder but only at those speeds. Once I am up to cruising speed it stops. I can't really tell which side the noise is coming from, but it does sound like the engine bay area. The car idles perfectly, accelerates perfectly, no hesitation/sputtering/backfire.

If it helps any, I do have an intermittent cranking problem (ALWAYS starts though). But I was going to test the battery and starting and charging system when school started back.

ANY help is greatly appreciated, I really really cannot afford a major repair right now!

JRad405

Was this happening before the mods or after? I would check all your fittings including exhaust stuff. Does this happen if you just rev the motor too? And what this noise sound like? i.e. chain rattling, or like some wire swinging around?

projectresto83

so it is just speed related and not RPM? so if you left it in 2nd and went to 45-50 it does it too?

Aya

I honestly don't remember if it happened before or after the mods, it's such a faint sound you have to have the raio and AC off to hear it. I just left work and revved my engine to about 1500RPM and didn't hear it at all. I also didn't hear the noise on the way home from work just now, but I live so close to work that my engine was still cold when I got home, so I don't know if the engine temperature could affect it.


And I don't know about leaving it in 2nd (got an Automatic unfortunately :P ), but it doesn't make the sound right before it shifts at about 45MPH, if that's what you mean.

I go back to school next Wednesday and my teach was a Master Tech at Ford for over 20 years, so if you guys could even give me some ideas as to what to look at it would help a lot and I can just try to figure it out at the school's shop.

JRad405

If you rev the car in park, does it make that rattling sound too? My car does it if I rev high but only if I'm driving. If I do it in park or neutral no rattling.

Aya

I only reved up to around 1500 RPM in park, but there was no sound at all. My coworker was standing on the other side of the car and said he didn't hear anything either while revving :/

JC316

Check the heat shield on the catalytic converter, they can break and make a weird noise. Could be pinging too if the timing is advanced too far in that tune.

johnmvtv

I got a tuner from am with bama tunes,and my car pinged pretty bad,,I had to call them and they sent me a new tune and no problems now

Aya

I called Bama tuning and they're sending me a new tune, they also told me to check the fuel filter on the car. It's low miles but almost a 10 year old car. I'm still in the process of changing fluids and filters and spark plugs etc. since there's no telling what the previous owners did or didn't do maintanence-wise.

Thanks for the help though! I'll keep you posted as to what fixed it ^__^

AMDanBailer

That's what I was going to suggest. Also, check your battery voltage/test your alternator if possible. Weak spark could be causing some ignition/combustion issues, so if the new tune doesn't help check that stuff out. Let us know how it goes with the new tune. If you're still having troubles, shoot me a PM directly, I'd be happy to look into your calibration for you!

Good luck! Have a great new years!