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Intake Noise/Shudding under light load around 1500 rpm

3813 Views 6 Replies 6 Participants Last post by  2021ChevyBlazerRs
Lately I have noticed my blazer is making some odd noises that seem to come from the engine compartment, sounds most likely from the intake.

After scouring the interwebs and this forum, I decided to create a new thread to try and track this specific issue since anything with noise, knock, shudder return many different things.

Noise is present in when vehicle reaches high gear and 70+kmph (45 mph) and rpm is just under 1500 to about 1550 rpm

Pressing the gas pedal slightly or if the vehicle is on a slight incline will result in a shuddering/hollow knocking/rattle from the engine compartment. you can hear it much more if the climate is on and vents open.

it almost feels like the transmission is holding the higher gear and lugging the motor because the noise disappears after a down shift.

I am taking it in to dealer tomorrow to have them look into it.

Specs:
2019 Blazer RS
Stock AF :(
37,500 KM

I am leaning towards bad vacuum pump as the intake holds vacuum for the EVAP system combined with AFM is amplifying the noise. tested purge valve and its working
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Lately I have noticed my blazer is making some odd noises that seem to come from the engine compartment, sounds most likely from the intake.

After scouring the interwebs and this forum, I decided to create a new thread to try and track this specific issue since anything with noise, knock, shudder return many different things.

Noise is present in when vehicle reaches high gear and 70+kmph (45 mph) and rpm is just under 1500 to about 1550 rpm

Pressing the gas pedal slightly or if the vehicle is on a slight incline will result in a shuddering/hollow knocking/rattle from the engine compartment. you can hear it much more if the climate is on and vents open.

it almost feels like the transmission is holding the higher gear and lugging the motor because the noise disappears after a down shift.

I am taking it in to dealer tomorrow to have them look into it.

Specs:
2019 Blazer RS
Stock AF :(
37,500 KM

I am leaning towards bad vacuum pump as the intake holds vacuum for the EVAP system combined with AFM is amplifying the noise. tested purge valve and its working
I’m having a similar Issue between 1500 and 1700 RPM. The issue does not sound bad it’s just annoying. I have it at any speed. I’m almost thinking the harmonic balancer has an issue. I will continue to follow this post and update as I find any new information.
I’m having a similar Issue between 1500 and 1700 RPM. The issue does not sound bad it’s just annoying. I have it at any speed. I’m almost thinking the harmonic balancer has an issue. I will continue to follow this post and update as I find any new information.
so it turned out that the EVAP solenoid was bad and need to be replaced. the noise itself is apparently the v4 mode. i can still hear the noise after they replaced the EVAP solenoid, but the transmission is not constantly up shifting now which is better as it was making the noise much more in higher gear. fuel mileage also seems to be back to normal, as it was running higher then usual.

also, i have a K&N drop in air filter which could be amplifying the v4 noise. i switched back to the OEM paper filter and noticed the noise is not as loud as it is with the K&N
I am glad I am not the only one. At first, it was so intermittent, I couldn't describe it to get it diagnosed. Now it is becoming more frequent, but I do notice that it seems to come from the engine. It sounds almost like a freight train, especially on an incline.

[QUOTE="swayzie_express, post: 13347, member: 1389"







Lately I have noticed my blazer is making some odd noises that seem to come from the engine compartment, sounds most likely from the intake.

After scouring the interwebs and this forum, I decided to create a new thread to try and track this specific issue since anything with noise, knock, shudder return many different things.

Noise is present in when vehicle reaches high gear and 70+kmph (45 mph) and rpm is just under 1500 to about 1550 rpm









Pressing the gas pedal slightly or if the vehicle is on a slight incline will result in a shuddering/hollow knocking/rattle from the engine compartment. you can hear it much more if the climate is on and vents open.

it almost feels like the transmission is holding the higher gear and lugging the motor because the noise disappears after a down shift.

I am taking it in to dealer tomorrow to have them look into it.

Specs:
2019 Blazer RS
Stock AF :(
37,500 KM

I am leaning towards bad vacuum pump as the intake holds vacuum for the EVAP system combined with AFM is amplifying the noise. tested purge valve and its working
[/QUOTE]
I am glad I am not the only one. At first, it was so intermittent, I couldn't describe it to get it diagnosed. Now it is becoming more frequent, but I do notice that it seems to come from the engine. It sounds almost like a freight train, especially on an incline.

[QUOTE="swayzie_express, post: 13347, member: 1389"

Hi, I just traded My 2017 Camaro for this 2019 Blazer. I bought the Camaro in March. I bought it on a Saturday. Every time I hit a slight incline it started shuddering. Did it on Sunday as I took it out again. On Monday took it back to the Dealer. They automatically knew what it was. Left it overnight. They said the ‘16 and ‘17 Camaros had to run Mobil One tranny fluid and it stopped the shuddering. Didn’t do it again. There are Camaro forums that talk about it, might be a shot in hell. Good luck.





Lately I have noticed my blazer is making some odd noises that seem to come from the engine compartment, sounds most likely from the intake.

After scouring the interwebs and this forum, I decided to create a new thread to try and track this specific issue since anything with noise, knock, shudder return many different things.

Noise is present in when vehicle reaches high gear and 70+kmph (45 mph) and rpm is just under 1500 to about 1550 rpm









Pressing the gas pedal slightly or if the vehicle is on a slight incline will result in a shuddering/hollow knocking/rattle from the engine compartment. you can hear it much more if the climate is on and vents open.

it almost feels like the transmission is holding the higher gear and lugging the motor because the noise disappears after a down shift.

I am taking it in to dealer tomorrow to have them look into it.

Specs:
2019 Blazer RS
Stock AF :(
37,500 KM

I am leaning towards bad vacuum pump as the intake holds vacuum for the EVAP system combined with AFM is amplifying the noise. tested purge valve and its working
[/QUOTE]
I had this problem with my 2019 blazer, @ 1500 rpm, they thought it was the purge valve but was the intake housing that needed to be replaced. I have a similar noise again that comes on at 1500 rpm and once it downshifts, hoping to get it into dealership, but I just rolled over 60K for warrant :’(
There is a tech bulletin out for transmission shudder. You can take it to the dealership and they will flush out your transmission and refill with transmission fluid and shudder will be gone. Or do what I did. I put my blazer on jack stands and drained and refilled transmission twice with Amsoil full synthetic transmission fluid (a much better fluid if you plan on keeping your car) and shifts super smooth. Shudder gone.
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