my ailing S4...+ "turbo drill sound of death question" (VERY LONG)
01-08-2002, 07:12 AM
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my ailing S4...+ "turbo drill sound of death question" (VERY LONG)
Sorry for the long message, but I know some of you guys complain about not enough posts during the day. This one should satisfy your need for audi-related reading material...
So I've had my S4 at the dealer for a week now for a list of problems (this doesn't include last months visit for gremlins in the radio and climate control unit):
1) Bad BPV makes honk + whooshing sound
2) F-hose has a tiny leak that has been blowing oily grime all over the engine for many months (9-12 months)
3) slow speed U-turn have a grinding noise from right front
4) mild accleration in 1st and 2nd causes loud "clunk" noise from right front (noise is directly related to force applied to engine/trans..."bucking" the car makes it worse
5) cruise control stalk malfunction
6) only get 7-8 psi boost (usually see 9-10 psi)
7) rattling noise from engine area at ~3000 rpm
They called me in to drive the car and see if all the noises have been resolved. Everything except the "clunk" and the rattling (#4 and #7). They were unable to duplicate these noises. But this is what was addressed:
1) replaced BPV from KS brand to Bosch type (anyone heard of the KS brand?)
2) f-hose replaced
3) right front wheel well liner was rubbing tire on full-lock left turns...put a screw in to hold the liner down
4) "clunk" noise could not be duplicated
5) cruise control contacts replaced
6) leak test (fill intake with smoke and look for leaking smoke) showed no leaks, but one of the TBB clamps was loose and tightened.
7) rattling noise could not be duplicated
In addition, the rear differential mount was replaced b/c the nose-cone of the rear diff. would hit the underside of the car under hard launches. There are obvious signs of rubbing on both the diff. and the underside of the car. Unfortunately, this was not the source of any sound I heard. In addition one of the heat shields was found to be touching the turbo housing and is suspected to be the cause of the rattling, except it turns out it wasn't.
So I spent about 2 hours yesterday driving the car around with the tech, looking under the hood, putting the car on the lift, etc...
i finally got the tech to hear and duplicate both the "clunk" noise and the rattle. Though now the rattle sounds less like a loose heat shield and more like a high-pitched drill. It occurs at 3500+ rpm but ONLY when accelerating. The pitch is constant and it sounds like someone is grinding metal on metal. It is definitely not the police siren sound that turbos normally make. The tech thinks it's detonation in the exhaust, I am hoping that it isn't the "turbo whine of death". Does the noise I describe fit the definition of the dentist drill sound of a dying turbo? Is there a way to determine if it is the turbo without opening it up?
Boost leak issue...tech says leak test passed + the Audi VAG shows the boost is in spec. I do not know if this leak test is conducted on pressure to emulate boost. I am worried that there may be either a leak in my gauge or gauge lines, or there is a leak between the ECU boost sensor and hose that my boost gauge taps into. Or worse, that the car is making normal boost, but the wastegate has to work harder to do so. Can anyone tell me (or show me a pic) of where the ECU boost sensor is located?
Anyone with ideas or similar problems?
So I've had my S4 at the dealer for a week now for a list of problems (this doesn't include last months visit for gremlins in the radio and climate control unit):
1) Bad BPV makes honk + whooshing sound
2) F-hose has a tiny leak that has been blowing oily grime all over the engine for many months (9-12 months)
3) slow speed U-turn have a grinding noise from right front
4) mild accleration in 1st and 2nd causes loud "clunk" noise from right front (noise is directly related to force applied to engine/trans..."bucking" the car makes it worse
5) cruise control stalk malfunction
6) only get 7-8 psi boost (usually see 9-10 psi)
7) rattling noise from engine area at ~3000 rpm
They called me in to drive the car and see if all the noises have been resolved. Everything except the "clunk" and the rattling (#4 and #7). They were unable to duplicate these noises. But this is what was addressed:
1) replaced BPV from KS brand to Bosch type (anyone heard of the KS brand?)
2) f-hose replaced
3) right front wheel well liner was rubbing tire on full-lock left turns...put a screw in to hold the liner down
4) "clunk" noise could not be duplicated
5) cruise control contacts replaced
6) leak test (fill intake with smoke and look for leaking smoke) showed no leaks, but one of the TBB clamps was loose and tightened.
7) rattling noise could not be duplicated
In addition, the rear differential mount was replaced b/c the nose-cone of the rear diff. would hit the underside of the car under hard launches. There are obvious signs of rubbing on both the diff. and the underside of the car. Unfortunately, this was not the source of any sound I heard. In addition one of the heat shields was found to be touching the turbo housing and is suspected to be the cause of the rattling, except it turns out it wasn't.
So I spent about 2 hours yesterday driving the car around with the tech, looking under the hood, putting the car on the lift, etc...
i finally got the tech to hear and duplicate both the "clunk" noise and the rattle. Though now the rattle sounds less like a loose heat shield and more like a high-pitched drill. It occurs at 3500+ rpm but ONLY when accelerating. The pitch is constant and it sounds like someone is grinding metal on metal. It is definitely not the police siren sound that turbos normally make. The tech thinks it's detonation in the exhaust, I am hoping that it isn't the "turbo whine of death". Does the noise I describe fit the definition of the dentist drill sound of a dying turbo? Is there a way to determine if it is the turbo without opening it up?
Boost leak issue...tech says leak test passed + the Audi VAG shows the boost is in spec. I do not know if this leak test is conducted on pressure to emulate boost. I am worried that there may be either a leak in my gauge or gauge lines, or there is a leak between the ECU boost sensor and hose that my boost gauge taps into. Or worse, that the car is making normal boost, but the wastegate has to work harder to do so. Can anyone tell me (or show me a pic) of where the ECU boost sensor is located?
Anyone with ideas or similar problems?
01-08-2002, 07:17 AM
#2
The turbo whine of death is not as high pitched as a dentist drill or police siren...
...it's more like an old hand crank fire siren in pitch, and you will absolutely know it ain't right if you here it. Are you making full boost now? Keep in mind that in cold weather, the ECU requests less boost than it has to in hot weather.
01-08-2002, 07:18 AM
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dude...sorry man, sounds like you had a car put together after beer break time in deustschland...
what are the lemon laws in your state? There are just WAY too many problems for a new car.
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01-08-2002, 07:38 AM
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Here's the ECU boost sensor (Charge pressure sensor G31)
<center><img src="http://pictureposter.audiworld.com/10011/sender.jpg"></center><p>I've heard of a broken N75 solenoid valve causing boost problems by the way.
