I just test drove a '03 CL Type-S 6-Speed and noticed a blow-off valve type of sound coming from the engine when I revved it to 3000 rpm and backed off in neutral. Can anyone identify the source of this sound?

 

Everyone from the Tysons meet remember this?

 

They must have put your technology to work!


Man if mine's in park and I rev mine to 3k and let off the rpms dip so low the car almost stalls out before going back to idle rpms.

 

What are you talking about?

 

Unless this is a joke I am becoming sickened by the level of knowledge based on the content being distributed.

I’ll wait to see the counter point.

 

 

I'm joking around with Joe about his BOV, but I'm serious about how my car almost stalls if I'm in Park and I give it a little gas slowly and then let off it at around 2500rpm. It drops off suddenly when I let off it and almost stalls before it jumps back up to idle rpm.

 

My point should have been more explicitly described. A BOV has a decisive sound which many people do not know but have heard the term and automatically assume.

My Typhoon had no BOV (since it is an automatic, anyone care to describe why an auto doesn't need a compressor bypass valve??) but people all too often thought it did have one.

 

So, I guess no one knows what i'm talking about?

 

im pretty sure i know what you're talking about...the neutral /park rev limiter...on my car its at 5k or 5.5K dont remember which...fuel cuts off so as not to over re while not under a load...

 

no, i know what you are talking about. It's a whine when you hit the gass and let off. And it's not the rev limiter either. i have it in mine too. Heard it when i first got the car. Hate to say it scalbert, but your typhoon had to have some type of pressure release valve to release the boost when you let off the gas. Maybe not a blow-off valve but something. The fact that it's a manual or automatic has nothing to do with it. Know what you are talking about before you criticize other people.

 

In fact, and I worked on that 4.3L Turbo quite often, it didn't have a CBV, BOV or whatever someone would like to call it. Also, the GN/T-Types didn't run a BOV either. I'm fairly well versed at those also.

Yes, being an automatic has everything to do with the final need of a BOV. The car doesn't need to close the throttle during a shift, you just keep your foot in it. Most people driving sticks will let off the gas during the shift and this is where the repetitive compressor surge occurs and leads to premature bearing wear.

So what occured when under boost and you let off the throttle?? Compressor surge, the boost backed out through the compressor housing and out the filter. This made a very distinctive sound, not completely pleasant. But it probably kept the filter cleaner...

In retrospect my sarcasm may have been a bit extreme but in the end I did know what I was talking about!!

 

another detroiter, welcome

I think that sound might be the intake im not sure