I have a 2005 S4 Cabriolet, so it has the 4.2 V8. The problem is when I first start the car after it has been sitting for some time, I have a noticable "whine," at about 1600 rpm. I have searched the internet and came up with three different situations.

1) The belt tensioner, but the TSB doesn't include my VIN.
2) The Secondary Air Injection, but this isn't rpm dependent so I wouldn't think it would be it. No CEL or codes
3) I have read about a ECU reprogramming related to the intake, don't know how this would cause the whine, but it sounds like the most logical thing. Haven't really seen much out there about this so I'm having a few doubts.

The whine sounds like air resonance problem, kinda like a whistling, like air flowing across a partially open valve. It doesn't at all sound mechanical in any way, like bearings whining. It only happens in a small RPM range at cold starts and goes away after a few minutes.

I hate to take it to a dealership, only to find out they couldn't find what was wrong then charge me an arm and a leg. I would hate for them to start replacing parts uncessarily to solve the problem. FYI, the car is out of warranty.

I could just crank up the tunes but I hate for my car to sound like this. Its not consistant enough to fool people into believing I have a supercharger, which it doesn't.

Hoping someone has had similar problems and can help out.

 

does it only do it when the car is first started...?

when does it go away...?

how long have you owned this car...?

when did you first notice the sound...?

and FYI the secondary air system isn't RPM dependent. its an electric air pump. And can be louder if the car has been sitting for along time cause its running at full capacity to warm the CAT up as fast as possible.

the 2005 S4 is known for the whinning noises it makes. and they are all normal.

 

It only does it on startup. If the car is warm or the outside air temp is higher than 60 degrees F, it doesn't do it.

It only takes about 3 minutes before it disappears.

I noticed the sound last winter, it didn't notice it this summer and its starting to come back since the weather is starting to cool down.

I don't think its the SAI, I do notice a louder start but its a consistant increase in noise. The whine is in addition to the SAI, just approx at a 200 rpm range around 1600 rpm. It doesn't do it while idling, you have to blip the throttle into the rpm range to get the whine. As the rpm increases and hits the mark, the whine starts and stops as it goes past the rpm range. I can hold it at 1600 rpm and it just whines. It above and beyond normal engine noise.

 

there is a TSB.


24-05-04, July 21, 2005

Engine, Intake Manifold Mounting Bolt Torque

Supersedes 24-04-02, July 6, 2004


Intake manifold bolts could loosen. This condition may cause erratic engine operation, poor performance and/or hissing noise from engine and high fuel trim readings in MVB 32.

Check torque of 14 intake manifold mounting bolts.

If intake manifold bolt torque is between 4-11Nm:

• Tighten intake manifold bolts in stages and sequence shown to 11Nm.
• Run engine for 10 minutes.
• Retighten intake manifold bolts in stages and sequence shown to 11Nm.

If intake manifold bolt torque is less than 4Nm:

• Remove intake manifold.
• Check intake manifold sealing surface for distortion.

If distortion is below .10mm

• Install new intake manifold gaskets (Part No: 077 129 717Q).
• Reinstall intake manifold and tighten bolts in stages and sequence shown in illustration 15-A073 to 11Nm.
• Run engine for 10 minutes.
• Retighten intake manifold bolts in stages and sequence shown in illustration 15-A073 to 11Nm.

If Distortion is between .10mm to .40mm

• Install new manifold gaskets Part No. 077 129 717Q and apply sealant (Loctite 5970) Part No: D 176 501 A1 (see TIP below) as follows:

• Apply a 2mm wide continuous bead of sealant around entire periphery of each intake port of cylinder heads (see dotted lines) prior to gasket installation.

• Immediately install new gaskets to cylinder heads (ensure gaskets are installed over metal alignment pins numbered 1).
• Secure gaskets to cylinder heads using threaded plastic alignment pins (pins numbered 2).
• Apply a 2mm wide continuous bead of sealant around entire periphery of each intake port of the secured intake gaskets (see dotted lines).
• Tighten intake manifold bolts in stages and sequence shown in illustration 15-A073 to 11Nm.

Tip:
After tightening manifold bolts to proper torque, the sealant needs to set up for one hour prior to starting the engine.

• After the sealant has set up, run engine for 10 minutes.
• Retighten intake manifold bolts in stages and sequence shown in illustration 15-A073 to 11Nm.

On All Engines

After tightening intake manifold bolts to the proper torque, place a Red paint dot next to engine code sticker as shown in appropriate inspection illustration.


TRY THIS

 

Torque Sequence is

11 / 14
7 / 10
3 / 6
1 / 2
5 / 4
9 / 8
13 / 12


Left / Right

 

I will check, I didn't have a torque wrench that would go that low or a torex socket at that size. They were hand tight with a screwdriver/torex bit. The sound doesn't seem to be orginating from the intake and I haven't seen any performance or milage decrease. What about the SAI valve? It is located in front of firewall on the drivers side, any problems related to this component that is similiar to my whine?

 

Was able to check today, all were in spec. Didn't remedy the problem.

Thanks for the advice.

 

Also read about timing chain whine in a few other threads. Checked out the YouTube videos for other S4. I am familiar with the normal whine associated with the drivetrain. Its more like a whistle

 

I have an 05.5 S4 with the same exact problem. Mine whinned last winter, and then I forgot about it until about a week ago when it got cold again here in Colorado - and the whine is back. I am still in warranty and would like to know if anyone else has the same problem or a fix before I call the dealer.

 

Mine is out of warranty, let me know if the dealership was able to figure it out.