Occasional extra whining from engine

[CJ_Boxster]

I have this annoying problem that happens occasionally. I will sometimes have alittle extra whining from the engine during acceleration or sustained speeds/rpms. Saying Im coasting at about 2800 rpm... and the engine whine will be kinda loud sometimes which makes the engine sound like im coasting at 4000 rpm's... And i hate it! Sometimes i dont have any extra engine whining and I can almost hear nothing from the engine while coasting at 3000 rpms... It comes and goes.

FYI, i have 2 secondary air-injection CEL codes at the moment... maybe related?

Idles nice and smooth even during loud engine whining moments.

Sometimes burns gas pretty quickly during gentle driving and sometimes wont.

1997 Boxster, 115,000 miles Original Engine.

Anyone else experience this?

Like alternator whine? Any aftermarket cd player?

[CJ_Boxster]

You know it could be alternator noise.

I still use factory cdr210 radio. stock speakers, sound isnt coming from the speakers. It literally sounds like im at 4000 rpms when im at 2800 rpms most the time i drive.

Do you think it could be my battery craping out alittle causing the alternator to whine?

I do notice that the radio will cut out sometimes for a split second when the engine bay fan or the air-injection pump triggers on.

[Paul]

I'd check the serpentine belt's idlers, tensioners, etc.

[CJ_Boxster]

Well the mystery is solved, turns out i had a vacum leak of some sort coming from the little hole below the gas cap (pictured below) which caused this whining. It original purpose is to suck up vapors while you pump gas into the tank, Its apart of the ORVR

"The system you are talking about is ORVR. This system recover the vapors let out of you gas tank when you fill up your car. It only works when you fill up your car and insert the nozzle into the filler neck. When you take off your cap, push in the flap and you should hear a click for the system to start. You might have a problem with the system, if you have vacuum in that hose when the car is running, you have an issue and should go to a dealer. Peter Smith - PCA WebSite - 9/17/2002"

SO place a peice of tape over it and see if this changes anything for anyone. I did and the car runs better and is finally stopped whining.

[blinkwatt]

Originally Posted by CJ_Boxster

SO place a peice of tape over it and see if this changes anything for anyone. I did and the car runs better and is finally stopped whining.

How does the car run better?

If there was something meant to be put over it wouldn't Porsche have made some sort of plug for it?

[CJ_Boxster]

Well It is suppose to only open and vacum suck the gas vapors when a gas pump nozzle enters the filler neck, You should hear a click when that happens, When there is no gas pump in the filler neck, No vacum should come from this hole... Reason for the tape is, In my case, when the gas pump is reomved from the filler neck, there is still a vacum coming from this vent hole.

In fact when i have my buddy give the throttle a nudge up to 3000 rpms, i can hear whining or howling from this vent. So that is a vacum leak which jacks up the a/f ratio, which makes the car run worse. I can always peal the tape back when pumping gas and reseal it once im done cause thats essentially how it was designed to work.

So somewhere along the lifetime of the car, the vent tube stopped closing itself once i pulled gas pump out of the filler neck

Well, now you know. (insert gay rainbow star here)

[CJ_Boxster]

Originally Posted by boggtown

Well, now you know. (insert gay rainbow star here)

Then "Reading Rainbow" theme song starts and we all learn about volcano's.

[kabel]

Originally Posted by CJ_Boxster

give the throttle a nudge up to 3000 rpms, i can hear whining or howling from this vent. So that is a vacum leak which jacks up the a/f ratio,

I must be missing something...
I can believe that being a vent, or an inlet for a vacuum, but it seems odd a vacuum system for venting refueling fumes would somehow be tied into the vacuum created by the engine. I mean, you shut your engine off when refueling don't you (i.e. no vacuum when refueling)? I admit I know little about all the compnants that make up an engine, do our cars have an electic vacum pump somewhere?

Ya gotta luv it when you can fix something with a piece of tape!