Still Have Cold Start Noise - Audio Sample

rev320 · Post by **rev320** » Mon Mar 28, 2005 8:19 pm

I still have the start-up noise with my Forenza. The following short clip was recorded on 26 March, with a 30 degree F. ambient temperature. My daughter was home for the holiday and I borrowed her laptop. I hung a microphone under the open hood, started the car, and put it into reverse. This is just a short clip. The noise sounded like this for about 30 seconds but became more continuous, and then faded away for about a minute until it disappeared entirely.

http://www.excel.net/~aj22hend/car02.mp3

Ideas?

kinkyllama · Post by **kinkyllama** » Mon Mar 28, 2005 8:21 pm

hmm.. are the RPMS dropping really low from 1k and down and it looks like its about to stall?

rev320 · Post by **rev320** » Mon Mar 28, 2005 8:23 pm

The RPM's are hanging right about 1100 to 1200 with minimal variation. The engine shows no sign of stumbling or stalling, but as one would expect, is not quite as smooth as when it is fully warm. The noise seems to occur at a very specific engine speed and slight variations above and below cause it to quit. Too bad the critical speed seems to be right at the fast idle setting.

kinkyllama · Post by **kinkyllama** » Mon Mar 28, 2005 8:25 pm

well that sounds like a problem ive had but only at start up sometimes.. it starts to stalll for a few mins and it goes "bddt bddt bddt" but if you were to start driving like taht it goes away untill you idle again and eventually stops

rev320 · Post by **rev320** » Mon Mar 28, 2005 8:32 pm

Yes, that's what it does on a cold start (really doesn't stall, just gets noisy) but it's very annoying and it's driving me nuts trying to figure out where it's coming from.

daewooluvr · Post by **daewooluvr** » Mon Mar 28, 2005 8:38 pm

wow that's weird sounding... maybe a deer caller?

rev320 · Post by **rev320** » Mon Mar 28, 2005 8:54 pm

daewooluvr wrote:wow that's weird sounding... maybe a deer caller?

Well, the microphone placement could have been a little better. The actual sound is not quite as "underwater bubbly" but it's close.

ChiPPy · Post by **ChiPPy** » Mon Mar 28, 2005 9:12 pm

Have you tried taking that audio sample to the dealership, to let them figure it out? It sounds like yout timing belt is rubbing slightly too.... althought the sound is rather muffled, so I could be wrong.

rev320 · Post by **rev320** » Mon Mar 28, 2005 10:34 pm

ChiPPy wrote:Have you tried taking that audio sample to the dealership, to let them figure it out? It sounds like yout timing belt is rubbing slightly too.... althought the sound is rather muffled, so I could be wrong.

Dealer had it for two days and heard the sound both mornings. The tech shimmed the timing cover just in case. Apparently ALL 2005 Forenzas make this noise. What in the world is it?

Post by **Efratech** » Tue Mar 29, 2005 12:42 am

I was almost running way when i played that... my speakers where almost at full volume, lol

Where was the mic located?

Efrain.

MMamdouh · Post by **MMamdouh** » Tue Mar 29, 2005 12:43 am

that is one hell of a sound

ok it is too loud and deep to be a belt thats for sure, i recon its a metallic body and if the sound appears at a particular RPM then that body is lose and that RPM cause it to "resonate" and cause the sound.

does that sound goes away when your car is hot?? if this is the case then it could be that object gets hot and expand and somehow fastens itself.

i think it can be your exhaust... i currently have a similar problem with my mid exhaust box, at a particular RPM it makes a rattling noise (RRRRRRRRRRRR)... not as deep as yours but it is irretating as hell.

could be some part of the exhaust hitting the underbody of the car, i had my problem with the protection scheild of the exhaust near the fuel tank.

try to get under the car during a cold start and hold the exhaust in different places and try to feel the vibration... make sure to find it fast before it gets hot.

every time i hear the mp3 i say...exhaust.

MMamdouh

rev320 · Post by **rev320** » Tue Mar 29, 2005 4:25 pm

The sound is loudest near the front right fender well . . . near all of the accessories and the air intake box. The microphone was placed between the engine and radiator directly abpve the power steering pump. My latest hypothesis is that there is a critical frequency that is setting up some kind of standing wave in the intake system . . .or that there is some sort of internal baffle or flapper that is resonating. I'll start it tomorrow morning with the air cleaner box open.

The sound does not really happen much above 40 degrees F. The weather is warming up, so I might only have another week or so to figure this one out.

MMamdouh · Post by **MMamdouh** » Tue Mar 29, 2005 4:31 pm

if that is the case then it could be the air box or the resonator... the sound seems to be magified in some enclosure so you are looking for a box with flowing air.

MMamdouh

rev320 · Post by **rev320** » Wed Mar 30, 2005 7:13 pm

I started it this morning up with the air cleaner box propped open. No difference, except we're getting warmer weather and the noise only lasted a few seconds. The only intake noise I heard was the sound of rushing air.

Hmmmmmmmmmmmmmm . . . .

rev320 · Post by **rev320** » Thu Apr 07, 2005 8:45 pm

I sent a letter and a CD of the noise to Suzuki headquarters in California. They sent a field engineer to the local dealer to look at my car. They found that the serpentine belt was just a hair too long. At a certain speed the belt would start to flutter and the tensioner would travel too far and start bumping on on its stop. They replaced the belt with one 8mm shorter (a Ford part) and the problem went away. They also fixed two other new cars on the lot that had the same sound.

I'm so happy . . . .