High Pitch Nois after Tune Up

[mowen]

2000 Chevy Blazer 73000 miles

I just had a tune up that included
- oil change w/ engine flush
- transmission fluid changed and filter changed
- fuel filter replaced
- all spark plugs and wires
- tires rotated

There is now a high pitched noise when i push the gas pedal down, while
driving, and when parked, the sound is has lower pitch at the beginning
and gets higher as i push the pedal the goes back down when at speed i can't hear it when standing out side the truck or under the hood but seems
to be the loudest near the passenger side floor board. The noise was not
present or not noticeable before tune up. If any has any ideas they
would be greatly appreciated.

Thanks
Matt

[swalt]

Contrary to what some of the opinions may be from other posters here, a restricted heater core could cause such a noise. As the flow is restricted and air that may be in the system (that causes the restriction - gumming) is forced into the heater core, it can make a whistle/high pitch under hard RPM's. Its possible, but given that you just had a tuneup, the PCV valve was likely changed. Make sure the vent hose going to the PCV valve is tight as well as the PCV itself in the rocker and make sure the hose going from the throttle body to the other side is also secure. The rubber elbow that goes to the plastic cap on top of the throttle body may have become loose if they did a throttle body cleaning. Secure it tightly with a tie strap.

[OverBoardProject]

I don't believe that you only did a tune up

You probably added a turbo charger , That's where the whistle is coming from!
Now you'll be blowing us all off the road if we're foolish enough to race you in your "stock" Blazer.

Just kidding, there's a good chance that swalt is right. I find that whistles are vaccum related.

[srbianats]

Make sure all the intake parts are connected securely. If you checked the air filter, you might have loosened the intake a little and air is being sucked through that small opening. Just a thought.

[mowen_matt]

I looked under the hood last night after reading the first reply to check things
out and i found the hose that is arrowed in the picture link not attached to
anything. I don't know what this goes to but i re attached it and thought
it would stop making the noise but it still does. My question is what does this
hose go to a was it bad that it wasn't attached. Also could this attributed the noise. I uploaded this picture to the first website i found i don't know where the links at the top of the pic came from.

Thanks
Matt

[OverBoardProject]

mowen_matt, the next time that you upload a pic please use a different site.
Or just post the pic instead of a link. There's a link to the instructions on the FAQ section.
You just never know when childern might be on here and you don't want them to see those titles at the top of the page.
Thanks ahead of time

I can't help you out since my stuff is all older, but I'll post the pic for you

[old_master]

That is the PCV intake line from the passenger side rocker arm cover to the air intake on the throttle body. It appears as though you have it connected properly. This needs to be connected. The vacuum flow direction is toward the rocker arm cover. Any dirt is ingested directly into the crankcase. If this line is plugged or restricted, a negative pressure could build in the crankcase and slightly suck in gaskets causing an oil leak. It’s important to check this line regularly; there should be a slight vacuum present while the engine is idling.

[OverBoardProject]

Thanks for removing the link mowen_matt

[swalt]

You may want to tie strap the connections as well. If the rubber elbow is a old, it may not seal as well around the plastic fitting. The noise you mention sounds very similar to what I had two weeks back. I just pulled the rubber elbow off and reversed it. It still didn't seal right as I could hear vacuum, but after tie wrapping it it seemed to fix the problem. One thing I did find odd is that you mentioned yours was completely off. When I pulled mine off, the truck would barely remain running.

[mowen_matt]

Thank you for getting my picture on. When i tryied posting it no link came up so i didn't think that it even worked. I don't know how long it was off it had made the noise for about 2 weeks and never looked to check hoses because i didn't think that i would be able to tell but after i read the first couple of replies i took a look and found that hose totaly not connected. I haven't had any problems with keeping it running. I will try to take it back of and switch it around and zip tie it. Then if noise persists maybe get a new elbow connection.

Thanks for all the replies sofar
Matt Mowen

[mowen_matt]

I put a zip tie on the connection and their was no change in the noise. Could this sound come from a alternator going bad. I noticed today that my shift display flutters a littlebit when at a stop light or parked.

Thanks
Matt

[Blazer SS]

Just a thought. The spark plug wires that you replaced, are they radio frequency shielded? If they are not, the faster the engine turns and the higher the frequency. that comes through your speakers.

[mowen_matt]

I'm not sure if wires are covered or not i didn't do the work myself. I don' think that is is coming from the speakers though. Also at the other end of the hose that is arrowed above is that the pcv valve or is that somewhere else.

Matt

[swalt]

Originally Posted by mowen_matt

I'm not sure if wires are covered or not i didn't do the work myself. I don' think that is is coming from the speakers though. Also at the other end of the hose that is arrowed above is that the pcv valve or is that somewhere else.

Matt

No. That hose leads into the passenger side valve cover. The PCV valve is in the driver side cover, just to the right of the arrow in your picture. While the vehicle is making the noise, try putting some downward pressure on PCV valve to make sure it is seating tightly to see if the noise disappears.

[Jeremy Fitch]

Sound like could be a vacuum leak under the dash. Check the vacuum lines.