[SS 1LE]

Well did an experiment yesterday, on a cold start right after the squeaky noise started I gave it a light rev to see if that would have any effect on it...it didn't.

I did listen to it more carefully, and it does seem to be coming from further back than the pulleys/belts. It only lasts 30-60 seconds tops, and it it seemed to stop for the most part when the engine dropped rpm and changed from the cold start loop. So I am thinking this is more so related to something there. Exactly what, not sure, and why whatever it is sounds like a noisy pulley is beyond me at this time still...

But since so many say they hear the same thing, I guess it is "normal"?

[gippy87]

Mine does it as well under the same conditions

[SS 1LE]

Originally Posted by gippy87

Mine does it as well under the same conditions

Yeah, I'm beginng to think this is "normal". Just sucks that GM didn't engineer this to sound better or be more insulated. Even though it only happens on a fully cold start, for less than 60 seconds at most, and as minor as it may be, it is bothersome...

[SS 1LE]

Finally was able to listen to my friends '17 SS on a fully cold (sat over 24 hours) start...it made the same, slight squeak/chirping noise for about 60 seconds on cold start as mine in his garage...

Normal (and yes, it is kinda quiet) or not, I hate this noise. I am so tuned in to hear it on cold starts in my garage it drives me nuts lol. I can't believe GM didn't think to insulate this better. If I knew exactly where it came from, I would try to insulate it myself...

[hawk02]

Well if it's any consolation, the LT4 in my ZL1 makes the same noise on cold startup. Just like everyone else, it only happens when the engine hasn't been started for 24 hours or longer.

I thought it might be the supercharger pulley squealing but since none of you have superchargers, that obviously can't be it.

I first noticed it around Christmas (cold temps) after my car had sat for more than a week without starting. Definitely something to do with cold startup.

I found a similar post to this one over in the C7 Z06 section of the Corvette Forums. I contacted the OP to see if he found a fix. He replied back that he never found a fix and has just learned to ignore the noise. Says his Z06 runs great, so whatever it is, it doesn't seem to affect performance.

I've been meaning to make a recording of the noise to post over in the ZL1 section to see if other ZL1s are making the same noise. If I get around to recording the noise, I'll post it here as well.

[SS 1LE]

Originally Posted by hawk02

Well if it's any consolation, the LT4 in my ZL1 makes the same noise on cold startup. Just like everyone else, it only happens when the engine hasn't been started for 24 hours or longer.

I thought it might be the supercharger pulley squealing but since none of you have superchargers, that obviously can't be it.

I first noticed it around Christmas (cold temps) after my car had sat for more than a week without starting. Definitely something to do with cold startup.

I found a similar post to this one over in the C7 Z06 section of the Corvette Forums. I contacted the OP to see if he found a fix. He replied back that he never found a fix and has just learned to ignore the noise. Says his Z06 runs great, so whatever it is, it doesn't seem to affect performance.

I've been meaning to make a recording of the noise to post over in the ZL1 section to see if other ZL1s are making the same noise. If I get around to recording the noise, I'll post it here as well.

Good to know, it defiantly doesn't seem to be belt/pulley related even though it does sound like that. Like you said, it only does it on a fully cold start for about 60 seconds...and it's so exact with how it does it, it must be something going on, then off. My guess is some emissions related thing to heat up the cats quicker...or possibly a DI related thing. If it's normal (which is seems to be), I am okay with that, but man, I wish they isolated the noise better for OCD folks like us lol...

I wonder if a tuner (EFI Tim?) who works on these car may know if it is emissions related of some sort? If so, if you were tuned you could potentially tune it out...

[slick3]

Originally Posted by SS 1LE

Good to know, it defiantly doesn't seem to be belt/pulley related even though it does sound like that. Like you said, it only does it on a fully cold start for about 60 seconds...and it's so exact with how it does it, it must be something going on, then off. My guess is some emissions related thing to heat up the cats quicker...or possibly a DI related thing. If it's normal (which is seems to be), I am okay with that, but man, I wish they isolated the noise better for OCD folks like us lol...

I wonder if a tuner (EFI Tim?) who works on these car may know if it is emissions related of some sort? If so, if you were tuned you could potentially tune it out...

I will piggy back off your final thoughts there.... Since I have been tuned, Tim lowered the RPM on cold starts. Normally it floats somewhere up around 1350-1500 when ice cold on a cold start, Now my car goes up to 1400 for only maybe a second or so, then back down to 1k and slowly trickles down from there.

I have not heard the noise at all since I have been tuned, I believe it could be something to do with the higher RPM start and slower decay rate.

Then again I added headers to the car and I cant hear shit now anyways lol.

[hawk02]

I got a good clip of the noise this morning. My car had not been started for nine days. Outside temp was about 50 degrees. The noise lasted approximately 99 seconds. What I posted is roughly the last 60 seconds. You can hear the noise periodically cut in and out.

Let me know if this is the same noise you guys are hearing on cold start.

[slick3]

Originally Posted by hawk02

I got a good clip of the noise this morning. My car had not been started for nine days. Outside temp was about 50 degrees. The noise lasted approximately 99 seconds. What I posted is roughly the last 60 seconds. You can hear the noise periodically cut in and out.

Let me know if this is the same noise you guys are hearing on cold start.

Cant hear what I think SS1LE is talking about. This is a pretty audible squeak chirping noise.

[SS 1LE]

Originally Posted by hawk02

I got a good clip of the noise this morning. My car had not been started for nine days. Outside temp was about 50 degrees. The noise lasted approximately 99 seconds. What I posted is roughly the last 60 seconds. You can hear the noise periodically cut in and out.

Let me know if this is the same noise you guys are hearing on cold start.

In your video I can faintly hear the slight chirping noise that I was talking about, but it is overpowered by a different noise there I have not heard. Like an intermittent wurring sound that comes and goes...my car does not do that.

[SS 1LE]

Originally Posted by slick3

I will piggy back off your final thoughts there.... Since I have been tuned, Tim lowered the RPM on cold starts. Normally it floats somewhere up around 1350-1500 when ice cold on a cold start, Now my car goes up to 1400 for only maybe a second or so, then back down to 1k and slowly trickles down from there.

I have not heard the noise at all since I have been tuned, I believe it could be something to do with the higher RPM start and slower decay rate.

See this is what I thought...must be an emissions setting then. The rpm doesn't hang that high unless the car is sitting awhile...even after 6-8 hours, it won't go that high on startup. So the fact you had Tim lower yours and that made the noise go away makes sense...my guess is a cat temp thing.

Next time you talk to Tim, ask him his thoughts, curious...god I wish they sold E85 near me...just another reason to tune lol.

[hawk02]

Originally Posted by SS 1LE

In your video I can faintly hear the slight chirping noise that I was talking about, but it is overpowered by a different noise there I have not heard. Like an intermittent wurring sound that comes and goes...my car does not do that.

Ok...I was hoping it was the same noise. Time to start a thread over in the ZL1 forum.

[gippy87]

its been pretty cold out up here and my cars been sitting a few days ill take a video of it tomorrow. I was initially convinced it was a pulley or belt because i have had belt squealing noise 2 times over 3000 miles. Odd cause the design shouldn't allow for any belt slip with a new tensioner and belt..

[SS 1LE]

Originally Posted by gippy87

its been pretty cold out up here and my cars been sitting a few days ill take a video of it tomorrow. I was initially convinced it was a pulley or belt because i have had belt squealing noise 2 times over 3000 miles. Odd cause the design shouldn't allow for any belt slip with a new tensioner and belt..

If you are talking about the same noise, it's not going to be the belts or pulleys. Some here have actually scoped theirs, no odd noises...seems to be something else. Enough have said they have it under the same circumstances, so I guess it's "normal".