Whistle noise

A spray can of throttle body cleaner.

Clean both sides of your throttle plate.

Return with good news.

Return with friends and family with vehicle problems.

The Medic

I neglected to mention, the third item replaced was a throttle body assembly. No positive results. This was done after cleaning the original tba with no positive results.

Reckon it will do it with the air filter removed?

The Medic

Yes, as a matter of fact the noise is worse. As a note, the air filter was replaced with the mass air flow sensor replacement.

Cleaned the interior of the snorkel?

Look for cracks, feel for internal molding imperfections (sand them out).

The Medic

No, I have not cleaned the snorkel. I will inspect and clean the snorkel tomorrow. I let will you know the results. Thanks

See you then.

If things are not getting better, I will see if there is another 2CarPro with other ideas.

The Medic

Well, inspected the snorkel with a cleaning too, no cracks or abnormalities. Also, more information: if you head is in the wheel well ( passenger side/air box side), you can really hear it.

So strange. Can you make a quick video with your phone of the noise and upload it in your response so we can see whats going on?

With the engine running can you use a pair of needle noise pliers and crimp off the vacuum line going to the brake booster please?

Cheers, Ken

There is no brake booster and consequently a vacuum line to crimp off. This system has brake lines, running through the back of the master cylinder area. I know what a boost system looks like. I have one on my 1995 Suburban. I am not able to do a video at this time. I would need an extra hand which is not available. The sound is like someone is blowing through a child's whistle. Also, the rpm range has evolved to not only include the original 1200 but also 1500 and 1700. The problem is getting worse. By the way the check engine light has never come on and there are no codes.

What about tweaking the MAF one way or another?

Or

Use some painters tape/ etc. that will not easily come loose and tape up sharp edges or the upstream side of the holes in the MAF.

Not trying to cover things up, just trying to disrupt the airflow over it to see if it is the origin of the noise.

The Medic

I will give it a shot tomorrow and get back. Thanks

Also spray carburetor cleaner around to see if you can make the noise change it sounds like you have a cracked intake manifold.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken

I like the ideas, especially the air intake manifold.

But, I cannot be two places at once. Producing the noise requires someone in the vehicle to depress the accelerator. In order to apply your suggestions with the noise occurring, a second person would be needed to manipulate the MAF or spray around the air intake for noise changes.

An acquaintance, who is a mechanic, knows a GM tech who has an extensive background with Gen III engines. He is going to consult on Monday.

Also, I have made an appointment with a local Chevrolet dealer for this Wednesday.

Okay great, please let us know what they say I am interested to see what it is. :)

Well, turns out that there was indeed a leak in the back of the intake manifold. The leak was found by first checking the fuel trim values for running lean, indication of vacuum leak. It was running lean. Next, a smoke test was performed. The back of intake was the source of the leak. Thanks for all the advice/support.

Nice work, we are here to help, please use 2CarPros anytime.

Cheers, Ken