Wierd noise on startup

[Bala]

My 2000 S 3.2 has been making weird noise on cold startup. This has been happening since I did the throttle body cleaning. It occurs only at cold starts and not when the engine is warmed up. It goes away in about half a minute. During this half minute car idle is pretty rough and then it smoothes out.

Below is the link to the audio file in m4a format. Windows media player or apple player would be able to play it.

The smoothing out in the audio file occurs around the 30th second.

https://docs.google.com/open?id=0BzNj15TtG1g_NjU0YTlmNzMtNmNkOC00MWM0LWJkO TEtNzIxNjhiZTE4NmMx

[Brad Roberts]

Great .wav file~~!! Seriously.. I have never heard one so clear!!

Lifter rattle at startup. How cold is it right now on "Strong Island"? What weight oil do you have?

After the rattle, I hear backfiring up through the intake plenum. Are you touching the gas peddle at this point in the file?

[Brad Roberts]

Did you use an Iphone to record it?

[Bala]

yes. used an eyephone to record. held it close to the vent so its clear.

Anyway i did not touch the gas pedal at all. the idle just smoothens out. after the 30 seconds the idle was little over 1000 rpm. when it warms up it stay around 700ish. i confirmed that thru Durametric as well.

there is a small vacuum tube that connects to the cross tube boot behind the tube where the throttle body is. the hole that this vac tube connects into was slightly cracked. seems like a tight fit to me but wondering if that has anything to do with this.

[Brad Roberts]

use that eyephone (funny BTW) to shoot a pic of that cracked hose

What you are hearing is a lean pop.. the MAF is not seeing the air leaking in AFTER the maf.. unmetered air is not good.

replace the cracked hose.. I think I have 8-10 of them or buy a new one


B

[Brad Roberts]

I'm not very smert.. pull that plastic line out and cover it with your finger. See if the idle changes. I now know which line you are referring too.

Did you determine the AOS was good?

[Bala]

AOS still not diagnosed. Car on stands for plug tube and fuel filter work.

BTW, the temp is about 38 now and it was around 24 this morning when i started the car. I shall take a picture of the broken tube boot as well.

[Bala]

Just changed the spark plug tubes, coil tubes. It was still cold and when i started it up i did not get the so called 'lean pop' sounds. However i did notice that one of the connectors for the coil on driver side was not all the way in. Meaning it was not 'clicked' in. Not sure if it contributed to the issue. Will try tomorrow again for a cold startup.

[Bala]

Started the engine and tried to open the oil cap. Just a slight suction. So, i guess AOS is good?