Whine under Partial-Throttle Acceleration

Nomake Wan · #1 07-31-2007, 06:51 AM

Okay guys, here we go. My #1 problem at the moment, now with more video.

This happens in the SVX at 3000 RPMs, under partial throttle when accelerating. Happens in any gear (easier to get to happen in higher gears because they're longer and revs are lower). What happens is you press the throttle, and when the engine gets to about 3000 RPMs a high-pitched whine happens. This lasts for a couple hundred RPMs but once you get around 4000 it vanishes (or is perhaps just drowned out by the sound of the engine).

The funny part is, this exact same thing happened in my old 1990 Subaru Legacy L sedan. And that car has a 2.2L Boxer and was FWD! In the Legacy it began around 2500 RPMs and ended around 3500, though. It made the exact same sound. Now I know the SVX transmission is different from my Legacy's (the Legacy's wasn't as smooth and 'luxurious' on shifts like the SVX, and the SVX is AWD), and I know the engines aren't the same either (Legacy is EJ22 SOHC, SVX is EG33 DOHC). But then what could it be that would make the exact same sound in these two cars?

Since a picture is worth a thousand words, I figured I'd go for the million and took some video footage of the sound in my SVX.

http://youtube.com/watch?v=dy-Y1Ugq7pY

Listen carefully right when it hits 3000 RPMs. That whine is what I'm talking about. I have more videos, but it'll take me a while to get them all processed and uploaded. That video should do nicely to demonstrate my problem though.

EDIT: Here's another video, this one's longer so it does it a lot more.

http://youtube.com/watch?v=sQ6JBEKFB-E

In this one, every time it gets to 3k the whine happens and then above and it seems to go away. Below and it doesn't exist. Weird...

Here's hoping there's a guru out there who knows exactly what this is!

SVX_MY_BABY · #2 08-09-2007, 03:37 PM

Gotta tel ya. I can't hear it. Then again hearing goes as you age.

Mine make a sort of whine which is a bit like a turbo (but not really) under hard acceleration. Always has since new and I've always been curious what causes it.

SomethingElse · #3 08-09-2007, 04:09 PM

sounds like differential..front or rear. have you checked fluids?

Nomake Wan · #4 08-10-2007, 03:16 AM

It did it since I got it, even immediately after the front and rear diff fluids were changed. My old car did it too...

Any way to check the diffs for damage? Would a Subie dealer be able to do that? The fluids are good, I know that for a fact... and the sound comes from the front, not the rear. Came from the front in my old Legacy too.

SomethingElse · #5 08-10-2007, 04:36 AM

You can simply smell the fluid to check if its been overheated. the best way to do it is chassis ears. they clamp on onto anything and go through an amplifier with some headphones..found bearings that way b4.

ItsPeteReally · #6 08-10-2007, 08:56 AM

Quote:

This happens in the SVX at 3000 RPMs, under partial throttle when accelerating. Happens in any gear

Well it's most unlikely to be the differential. If it was, it would most likely be dependent on road speed not engine speed.

You are in luck, because the same noise should be evident when you are stationary, so you can get your head right up to the engine and listen.

If you can't pin down where the noise is coming from, you can localise the noise by putting a screwdriver (or similar object) on a suspect part and holding the other end against your ear (you've not got long hair have you? --- if you have, be careful!!!

) This cheap 'n' cheerful stethoscope is a great discriminatory tool.

I'm not a betting man, but the power steering pump might be worth a listen.

Nomake Wan · #7 08-10-2007, 12:52 PM

I know the screwdriver trick, I used it to diagnose the ticking noise I got when I first got the car (man our fuel injectors are loud!).

But that's the real problem. It doesn't happen except under load. If I park the car and put her in neutral and rev up, I can't hear the whine. The Legacy was the same way...

I've gotta find a way to rig up something to record parts of the engine bay while driving. I hope it's just a vacuum line or something making noise...

SomethingElse · #8 08-10-2007, 03:52 PM

the second video almost sounds like exhaust buzz. its really hard to diagnose without hearing it in person. It if it only does it while the car is under load I would more than likely think its drivetrain related.

Nomake Wan · #9 08-10-2007, 06:44 PM

I really wish I had someone to ride along who knows these cars...

If it's just exhaust buzz, I'm probably going to laugh myself silly once I get the custom system put on...

Dessertrunner · #10 08-10-2007, 09:32 PM

Can't hear the sound but my guess is that both cars have a "Induction control value" on the intake manifold. This change the air flow path and ther by changes the sound. I would also suggest that you look at the underside of the manifold at the front between the power steering and the alternator as there is a small vacum hose that comes off a plastic box. This hose generally breaks away from a plastice value. What you might be hearing is the vacum leak or the IC value partially opening due to the leak. THis only operates around 3,000 rpm.
Tony

Nomake Wan · #11 08-10-2007, 11:29 PM

Quote:

Originally Posted by Dessertrunner

Can't hear the sound but my guess is that both cars have a "Induction control value" on the intake manifold. This change the air flow path and ther by changes the sound. I would also suggest that you look at the underside of the manifold at the front between the power steering and the alternator as there is a small vacum hose that comes off a plastic box. This hose generally breaks away from a plastice value. What you might be hearing is the vacum leak or the IC value partially opening due to the leak. THis only operates around 3,000 rpm.
Tony

References from EJ22:

(Pages 14 and 17) http://surrealmirage.com/subaru/files/SAE_boxer.pdf

http://www.lovehorsepower.com/images...ter/finish.jpg

http://surrealmirage.com/subaru/imag...ndcoilpack.jpg

http://www.swaqvalley.com/images/199...k/IMG_0840.jpg

I don't think the EJ22 has the same intake design as the EG33 does but I could always be wrong...

Nomake Wan · #12 09-05-2007, 02:18 AM

I now have videos of my old Legacy making the same sound. They were on one of my backup drives.

http://youtube.com/watch?v=XV6mIeYRtTg

http://youtube.com/watch?v=UzY9XVYB3pw

http://youtube.com/watch?v=9btcz16bXXQ

It's only while accelerating (vanishes once gas pedal is released). And only if it's partial-throttle (about 60%-85%, when the pedal starts to give resistance). And only in a certain rev range (though this could simply be the engine drowning out the sound).

DansSVXBlues · #13 02-09-2009, 01:56 AM

So... What did you finally find this problem to be? I have a 94 FWD with a whine that increases in both pitch and volume only under load of acceleration . As soon as I take my foot off the gas or coast at any speed, the whine stops. I have already done the $1 o-ring replacement for the power steering pump w/ no change.

While I was at it, changed the internal tranny filter, added and external tranny filter, and changed differential fluid. Differential had a noticable amount of fine metallic flecks stuck on the magnetic plug.

I'm hoping this might be a power steering issue as opposed to the differential. There's an order of magnitude difference in cost.

-Dan

VICSVX · #14 10-10-2009, 02:40 PM

Quote:

Originally Posted by DansSVXBlues

So... What did you finally find this problem to be? I have a 94 FWD with a whine that increases in both pitch and volume only under load of acceleration . As soon as I take my foot off the gas or coast at any speed, the whine stops.

I'm hoping this might be a power steering issue as opposed to the differential. There's an order of magnitude difference in cost.

-Dan

mine does the same thing....and started about a month ago

is it something to fix asap or is keep an eye on the fluid?