Screech sound on hard acceleration- has anyone actually identified source?

rocketspeed · Dec 16, 2003

I've searched around a lot and there have been a number of threads on this, but nobody seems to have any answers other than some speculation.

To be perfectly clear, I am not talking about the normal whine/whistle of the turbo that increases with RPM's.

I'm talking about a loud, additional screech noise that appears erratically when the engine is boosting under heavy throttle. The sound is sort of metal on metal in nature, or you might compare it to a loud slipping belt.

It seems to be quite common based on the threads I've read.

Anyone know for sure what causes this?

ARunto · Dec 16, 2003

it's the bearings on the turbo when under load.

DiscreetSpeed · Dec 16, 2003

boost leak?
have you had someone rev it up while your infront of the vehicle with the hood up?

DiscreetSpeed · Dec 16, 2003

ARunto said:
it's the turbo

i hope not

Notorious · Dec 16, 2003

Wastegate or the turbo bearings.

rocketspeed · Dec 16, 2003

Its definately not the whine/whistle associated with the operation of the turbo. I can clearly hear the turbo spool up, with the sound level coming up with RPM's.

This is intermittent and can pop up at almost any RPM level, but only in the 1st 3 gears and only under heavy throttle. Its very shrill and does not get louder as RPM's come up. You might get it at 3k for just a fraction of a second in first, 5k for longer in second, 3k for 2 seconds in third, then nothing- or any combination- seems completely random.

I have seen the jillion threads, which contain lots of conflicting answers- from oil starvation to bad turbos to no problem at all.

It seems plausible that this is normal for a ball bearing turbo, but then why is it hit or miss? Sometimes it happens, sometimes it doesn't.

I'd just take it in and have it looked at if I didn't think it was common to all MSP's. Seems to be.

rocketspeed · Dec 16, 2003

DiscreetSpeed said:
boost leak?
have you had someone rev it up while your infront of the vehicle with the hood up?

If I had a boost leak, the car would run rough, no?

Notorious · Dec 16, 2003

not always, i had a boost leak for like 2 weeks before i noticed. Mine was minor though.

1sty · Dec 16, 2003

I take it you can't pin point where its coimg from?
ANy idea of even what side of the engine its emitting from?

Black Majik MSP · Dec 16, 2003

Do you have any mods on the car?

Do you know any other MSP owners near where you live? If so, have someone else ride in your car so that they can hear the sound too & maybe help you figure out what's causing it.

If all else fails, take it to the dealer. You could even ask the service guy to ride in the car with you so you can demonstrate FOR THEM what's wrong. Ever since my old 626, I'm skeptical about letting them test drive it in order to figure it out on their own.

rocketspeed · Dec 16, 2003

Really hard to tell, as I can't seem to duplicate it when the car is standing still, seems to need to be under load. Its does seem tied to the turbo boosting up, though. Its heavy throttle- and I would assume (I don't have a boost guage) high levels of boost as its only when I'm hard on the gas and quickly increasing RPM's. Doesn't need to be high RPM's, though- lets say I accelerate hard in 2nd, but don't run it to redline- say I shift at 4k, then RPM's drop as I hit third, but I floor it in 3rd- might get a screech there down low in the RPM range.

ARunto · Dec 16, 2003

I've found mine does it when going 100mph+ No boost leak though. My friends with ball bearing turbos all have the same sound.

-Alan

rocketspeed · Dec 16, 2003

Black Majik MSP said:
Do you have any mods on the car?

Do you know any other MSP owners near where you live? If so, have someone else ride in your car so that they can hear the sound too & maybe help you figure out what's causing it.

If all else fails, take it to the dealer. You could even ask the service guy to ride in the car with you so you can demonstrate FOR THEM what's wrong. Ever since my old 626, I'm skeptical about letting them test drive it in order to figure it out on their own.

No mods. Unfortunately, I don't know a soul with an MSP. I've seen one on the road ever other than mine, and that was on a road trip in CT.

rocketspeed · Dec 16, 2003

ARunto said:
I've found mine does it when going 100mph+ No boost leak though. My friends with ball bearing turbos all have the same sound.

-Alan

The fastest my car has ever been is about 90, as I've been running snows since before the end of the break-in period.

This most frequently occurs in 1st and 2nd, so its south of 50mph for the most part.

ARunto · Dec 16, 2003

well once you break in and do your first top end run it will do it and it's noticeable...one thing i have noticed is that you can hear this screech more when you have stock exhaust and stock airbox...once you go with a aftermarket setup it's less audible but is still there.

-Alan

Black Majik MSP · Dec 16, 2003

Any MSP owner/Protege owner familiar with turbos live near him & want to help him out. I can't imagine you're the only one in MA.

rocketspeed · Dec 16, 2003

Its scheduled to go into the shop on the 26th to have the rear sway bushings replaced.

I'd suspect whatever the noise, the dealer will tell me its normal as long as the car is running OK. This has been my experience in the past.

rocketspeed · Dec 16, 2003

ARunto said:
well once you break in and do your first top end run it will do it and it's noticeable.

-Alan

I'd expect it to do it at 100 if it does it at 25.

I wish I didn't have to run snows in the winter! Its still pretty fun to drive with them (drifting machine!), but it does take a lot of the handling away.

ARunto · Dec 16, 2003

rocketspeed said:
Its scheduled to go into the shop on the 26th to have the rear sway bushings replaced.

I'd suspect whatever the noise, the dealer will tell me its normal as long as the car is running OK. This has been my experience in the past.

It's normal...I've heard another MSP do it as well. Some do it more and louder than others.

-Alan

rocketspeed · Dec 16, 2003

It does seem as though it is common, having reviewed a load of the threads.

Doesn't seem to be an immediate cause for alarm, anyway. Thanks for the help, all.

Screech sound on hard acceleration- has anyone actually identified source?

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