Brand new Cobra with strange sounds-detonation?

[Phxcobra]

Hi all,
I just bought a new 2003 Cobra and I've noticed a strange noise from about 2500-3500 rpm independant of gear. Sounds sort like BBs in a jar or sorta like a pulley with a bad bearing. I've done a search and read about some people with a marble-like noise and thinking it's just sounds from the supercharger. I thought perhaps the dealer filled it with their 87 octane stock they have so I've run the tank down to 3/4 twice now and fill up with 100 octane racing fuel. That's a total of about 10 gallons of 100 octance added. I still hear it. I just added the second 5 gallons of race fuel so maybe it hasn't mix well enough to make a difference if it is detonation. Any ideas? It's only got 200 miles on it.

thx,
Pete

 

[FuShnickens]

since it's so new i'd take it to the dealer as soon as possible. hope it's nothing bad.

 

[04-MystiChrome]

The race fuel could be your problem.
Does it have all stock pulleys?

 

[Phxcobra]

It's totally stock. I picked it up 3 days ago. And the race fuel is unleaded pump from mobile (Trick 101) and 76 (100 octance). If anything, the race fuel should help if it is indeed detonation. It's weird though, because it's always in the same rpm range and it doesn't seem to matter how much I'm into the throttle.

 

[stangin]

Whatever you do, dont tell the dealer you put in race fuel or anykind of additives.. they are voiding warantees for this.. Since you put the race fuel, I suspect it is not detonation. Maybe an exhaust leak? Since it is so new I would take it back in and let the dealer check it out, just dont tell em about the gas lol, good luck.

 

[davidmax]

The way you describe the problem sounds like detonation could be a bad blower pulley.DO NOT TELL THEM YOU HAVE ADDED ANYTHING BUT 91!!!!!!,they may view the additives in the 91 as octane boost and they will void your warrantty.
Call my shop Mon ask for Chad my lead Ford tech and ask him which dealer to go to I think its 5 star,but remember the dealer Chad gives you is Mod friendly in case later on you want more power and with these cars its almost impossible to not mod them
I am assuming you went to to the station on Bell and 56th street if it was there gas stinks 5000 gallon tank and if they sell 500 gallons a week I would be shocked.we sell 104 out of drums best way to but we dont make money but its a service we provide and its a great always fresh fuel.
Call Chad at 480-517-4969 and get to that dealer ASAP and let us know how it went for you we could very well be talking crank bearings and we can play advisor at no charge,community service and we do tons now we need to find some real paying customers,OH Thats what we've been doing wrong.
Just playing call us and we will help you out,David Smilovic

 

[Phxcobra]

Thanks a lot David. I'll give you guys a call tomorrow morning.
thx,
pete

 

[loose nut]

sounds like you are discribing a noise that is not that uncommon on Eaton blowers. It is from a coupler in the blower snout...some make the noise and some do not (two of my 03's did).
Look on eBay in the automotive parts auctions under "coupler" and you will find a couple of aftermarket companies selling a fix.
It doesn't seem to hurt anything, its just annoying. :beer:

...otherwise, you can fight with the dealer to fix it...but likely they will say it is "normal".

 

[CobraBob]

Very nice of David to step to the plate and help you out. His advise sounds like the best and you'll hopefully be at peace. Good luck!

 

[Phxcobra]

Hmm, I called Chad and didn't really seem to havea clue about which dealer to take it too. Oh well, I made an appt with 5 star for tommorrow. We'll see if it's just a noisy eaton or something more.:shrug:

 

[StreetSnake]

Pete I know we all hate to take these things back to the dealer, but what were you thinkin? Pete you could have possibly voided the warranty on a 12 grand engine, As most of these guys on this forum remember the guy whose warranty was voided because the dealer claimed he had added an octane booster. Take advantage of the wisdom on this forum their are a helluva alot of guys and girls who know what they're talking about. This by no means is a flame, I just dont want to see you screw the pooch on your warranty:beer: :beer:

 

[1992B4C]

Hey Pete, let me know what service advisor you see at 5 star. That is where i will probably take mine in. BTW, where did you buy yours? I'm in Mesa and got mine last Nov. at 5 star.

 

[Phxcobra]

Originally posted by StreetSnake
Pete I know we all hate to take these things back to the dealer, but what were you thinkin? Pete you could have possibly voided the warranty on a 12 grand engine, As most of these guys on this forum remember the guy whose warranty was voided because the dealer claimed he had added an octane booster. Take advantage of the wisdom on this forum their are a helluva alot of guys and girls who know what they're talking about. This by no means is a flame, I just dont want to see you screw the pooch on your warranty:beer: :beer:

Streetsnake,
No offense taken. That's why I posted here first, and I'm thankful for the advice. Seems lame that they'd try to deny warranty because you use higher octane gas. But, I'm glad I found out before calling them.

1992B4C,
I'm set up to see Shane at 5 star. I'll let you know how it goes. And I bought it through Lou Grubb on Friday.

 

[1992B4C]

Cool!

 

[05 Roush]

I know this sounds stupid but it could be bad bearings in the Power Steering pump. I talked with my guy at Bell Ford and he said that the pumps are so cheap on these things that they can cause noise, like a tickey rattling sound at different engine speeds.

Could be worth a check. :shrug:

 

[Got5onIt]

Since it only occurs at a specific rpm could it be exhaust rattle? :shrug:
My 2001 lightning had this disturbing metallic sound at a certain RPM(can't remember exact RPM). Just had to reseat the exhaust.

 

[Phxcobra]

Don't know. Just figure that since it's a brand new car, it shouldn't be making this noise. I figure better safe than sorry, so I'll just let the dealer havea looksie.