dkillgore

Hey guys. I just recently bought a 2003 GT Convertible and am loving it so far, but the car is making a strange noise. Whenever I am not accelerating, whether it be coasting or sitting still, I hear some sort of hissing noise coming from somewhere under the hood. Whenever I accelerate the noise stops until I take my foot off the gas.

Anyone have any ideas as to what this may be? The car has just under 60,000 miles on it and is stock as far as I can tell.

Thanks, and I hope you all had a good holiday season.

witch doctor

I'm going to throw hydroboost out there. I haven't had the chance to fully read up on it, but that's what first came to mind.

dkillgore

If you wouldn't mind, could you explain what hydroboost is? I have hardly any experience working with cars. I'm 19 and this is really my second car. I traded my first one in to get this one a few days ago.

witch doctor

Sorry. The hydroboost system is part of the brake booster. It takes hydraulic pressure from the power steering system and uses it as a backup/assist for the vacuum powerbrake system. Since you don't say anything about rough running, it almost can't be a vacuum issue. I'd be looking for a sticky valve in the hydraulic side of that system.

I could be way off base and someone with more Ford experience will probably chime in soon, so don't run off to the parts store just yet. ;-)

PROMETHEUS PRIME

I woukd say that the hissing is coming from your IAC. Especially since it sounds like it is only happening with your foot off the gas.....That or a vacuum leak. Do you have a check engine light on?

kugzgt

check all your vacuum lines

dkillgore

What does IAC stand for?

I do not have a check engine light on at this time. If it does come on I'll be sure to let you guys know about it.

I will also do my best to check the vaccum lines.

Thanks guys.

PROMETHEUS PRIME

This is your IAC.

It's an idle air control valve and it is what supllies are to the engine when the throttle plate closes. Check to see if it is the valve itself or maybe a hose running to it.

PROMETHEUS PRIME

Where abouts in California are you?

dkillgore

I'm in Los Angeles.

I'll check it tomorrow morning when I wake up.

Thanks!