[UncleMcMicheals]

2003 gt cats back exhaust, CAI, Plenum, TB, SCT tune done professionally.

Sounded like a pinging noise at first. It will usually happens in 5th and I have the five speed. If you have the car in low RPM lets say 2,000 in 5th it will make a very distinct rattling / pinging noise under acceleration.

It doesn't happen at idle or anything other then just sometimes in 4th which is even more strange. Also it doesn't do it all the time, but it does occur quite often. When it happens I usually throw it into a lower gear and it goes away. I believe my tranny mounts are in good condition so probably not that.

Now the guy who tuned my car said he is absolutely sure its not pinging but the noise is very very similar.

I was thinking it might be a clogged cat I'm not sure any ideas in the right direction will help thanks.

[UncleMcMicheals]

Also just to be clear as a rule of thumb usually if I can't hear it in the cab while driving then I usually don't worry about it I mean the car is getting old. But you can hear this in side the cab its not super ridiculous loud but you can hear it. And my exhaust is loud as s***!

[racin366]

First thing that comes to mind is bad gas or the tune may be overly aggressive, too much timing or lean.

If you are running 87 octane, stop that.

[UncleMcMicheals]

Originally Posted by racin366

First thing that comes to mind is bad gas or the tune may be overly aggressive, too much timing or lean.

If you are running 87 octane, stop that.

Sorry I shouldn't have been more specific its not pinging at all the sound just sounds similar. I had one of the best tuners in San Diego tune it. It runs very well idles perfect great acceleration. But when I gas it in high gear it makes a chattering/rattling noise I'm not going to use pinging because its not pinging.

[jerry9665]

That chattering sound could be detonation. Do you hear it when you've been driving for a while and the engine is warm?
Also, could be the catalytic converters going bad. How many miles on it?


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[pmanchin]

Its a long shot but when I installed my off road pipe on my mustang, the air flow was so much more better, it rattled one of the deflectors/baffles loose in my olddddd flow masters (8 years old?) And made an annoying sound.

PDM Designers

[2Manystangs]

dude it's knocking...

[UncleMcMicheals]

[quote=2Manystangs;3405497]dude it's knocking...[/QUOTE

Nah its not a knock I know what your saying, but there is no way it has been knocking like that for 3 years now. If it was knocking like that for the past three years and no problems or side effect.

Not a Cat problem, I had 70,000 miles on it and it has been well taken care of. My friend has a 2002 GT same thing.

If it was knocking it would be more of a knocking noise but its a rattling.

It could be the x pipe when I town shift from 3rd to second you can hear the exhaust hitting something that could be it.

Also if it was knocking I would have caught when I data logged it. When I data logged it, everything was perfect.

[UncleMcMicheals]

Bad tranny mount right side. I replaced both of them with steeda's, they looks pretty good nice and rubbery they should hold up to when I go to a S/C application.