Startup noise

[DvKillar]

my 2015 2LS V6, only had a couple of weeks, but trying to determine if the startup on this is normal. cold startup with ambient temps in the mid 60's. it goes straight up to 1500 rpm with what sounds like extra noises in the background. then, at about 20 seconds, it backs off to idle around 5-600. the extra noises disappear!

it is hard to describe and tried to record it a couple of times on my phone but didn't record well.

the extra noise sounds normal, but like something else is running during that first 20 seconds. kinda like a sewing machine sound!

any ideas?

[CarbonMaro]

It could be your AC compressor. I had some front end damage to my 2014 and ended up having to replace the compressor. after then it always makes that awful sound when i switch the AC on. i would try starting the car with the AC off and and see if the noise is still there. that the only thing i can think of that could sound like a sewing machine.

[DvKillar]

Haven't even used AC but once so far. I normally leave the climate control off and windows down
I will try and get a sound bite to post.

[Kenny Camaro]

Could it be the heat shield on the exhaust? Mine buzzs a little at cold start then goes away.

[1Coopgt]

Originally Posted by Kenny Camaro

Could it be the heat shield on the exhaust? Mine buzzs a little at cold start then goes away.

This right here.

[DokWatson]

My car had all kinds of heat shield noises before I deleted the cats. They are bolt on heat shields IIRC, might have had one loosen.

[gringo]

Try to cycle the AC at least once a week. I helps lubricate the seals inside the compressor. It's always good to run the system every now and then even if you don't use it.

[bistikDM]

Mine does the same thing on cold start, revs to about 1.5k and then back down to under 1k after 10-15 seconds. I would think it's just the car pumping and circulating fluids to all the necessary components because if you do a warm start it doesn't do that. Try it out! My car doesn't do it if I just run to the store and pick something up real quick before the engine has a chance to fully cool down.

[DvKillar]

Originally Posted by bistikDM

Mine does the same thing on cold start, revs to about 1.5k and then back down to under 1k after 10-15 seconds. I would think it's just the car pumping and circulating fluids to all the necessary components because if you do a warm start it doesn't do that. Try it out! My car doesn't do it if I just run to the store and pick something up real quick before the engine has a chance to fully cool down.

Mine won't do the 1.5k thing if engine is warm.

[DokWatson]

Originally Posted by bistikDM

Mine does the same thing on cold start, revs to about 1.5k and then back down to under 1k after 10-15 seconds. I would think it's just the car pumping and circulating fluids to all the necessary components because if you do a warm start it doesn't do that. Try it out! My car doesn't do it if I just run to the store and pick something up real quick before the engine has a chance to fully cool down.

Its heating up the cats. If the car has already been run, the cats are still hot.

[DvKillar]

If weather (dang wind blowin down the plains all week!) agrees, I will get a vid tomorrow. It could be cats getting warm, but it is all under the hood where I hear the extra noise.

[blackswan]

I know the sound you are talking about, my 2012 has always had this. Guessing normal.