[brownactive]

Last night was the first night we got down to about 20-25 degree. When I started the TB this morning there what sounded like a fairly loud deep bass like sound from the motor. It went away after about 5 seconds. I have not heard it since (driving it today). I thought it was the radio as the wife left it on but that system does not put out that type of sound.

 

[William’s RedTop RS]

My best guess: because if the cold start, and because it’s got a turbo, it might have just been at the right RPM for it to resonate a bass tone. Any problems with it since?

 

[brownactive]

Has not done it since, warmed up today. Going to be cold tonight so see how it is in the morning.

 

[William’s RedTop RS]

Cool beans! Let us all know.

 

[ZR2LIFE]

30 is the coldest we've had, but I haven't noticed the sound your describing. We usually use remote start when it's cold so it's possible we've just never heard it especially if it only lasts 5 sec. I'm assuming you were inside the car when you heard the noise? Any chance it was the ANC trying to drown out some unwanted engine harmonics?

Steve

 

[brownactive]

I had just started it and and the low bass sound was present like for 3 to 5 seconds then it faded away really fast. The radio was on but not loud.

 

[brownactive]

It did it again today. Not as bad but at idle it was there, if I goosed it a little it went away till rpms came to an idle and then it was there again. Went away after a little bit. Radio was on, I turned it off, made no diff. Seemed almost like an exhaust tone as the sound seemed under the car front to back. Maybe some type of resonation issue.

 

[ZR2LIFE]

It does sound like a harmonic resonance. I know these 3 cylinder engines like to vibrate at idle and low rpms. They don't smooth out until the rpms get higher. Most engines run a little rough until they're warmed up, so combine that with an engine that already likes to vibrate and you end up with weird noises that aren't normally there. If the noise didn't go away I'd be worried, but it sounds normal.

Steve

 

[ZR2LIFE]

I'm not sure if you've ever noticed, but alot of manufacturers weld weights to various areas of the exhaust to get rid unwanted resonances. I've had several GM vehicles with these little weights. Who knows maybe a TSB will be released some day for the Trailblazer to add weights to the exhaust.

I've already started buying new exhaust parts for custom system which I'll share once I'm all done. I just can't stand how quiet this car is, lol.

Steve

 

[Trail Blazed]

Please do. I am curious to see how this will look and sound. There was an era of snowmobiles that had 3 cylinders and people loved them when they added aftermarket cans on the exhaust system. I wonder if they will sound similar. Although those were 2 cycle engines.

 

[brownactive]

It was about 40 out today when I got out to drive the car about 2pm. No deep noise that I had heard.