TSI squeal noise problem on acceleration

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Originally Posted by logger

From observing the cars telemetry I can tell you that it isn't. The supercharger engages very briefly but quite frequently...

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Originally Posted by cktsi

I think he was making the comment in relation to the MkV TSI...

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Yes, I was referring to the BLG engine code version of the 1.4TSI in the Mk5 as described in ERWIN SSP 359. Page 13 in the section Constant boost range of supercharger says "From a minimum torque requirement and up to an engine speed of 2400 rpm the supercharger is constantly activated. The supercharger boost pressure is controlled via the regulating flap control unit."

From Logger's observations this is obviously not the case with the Mk6 TSI engines.

..and nor is it for the BLG engine. As I stated "Be interesting to know what the minimum torque requirement to engage the S/Charger below 2400revs is...." If you re read your reference you will see it does not say the SCharger is constantly active below 2400rpm. It says from some nominal "minimum torque requirement" of x & up to 2400rpm it is constantly active. I am wondering what x is.
So when x torque is commanded revs rise quickly to 2400 rpm and SCharger clutch disengages because boost demand is now met by turbo alone. This takes 2-3 seconds. When < x torque is commanded revs rise slowly to 2400 and beyond without SCharger.
If indeed it was constantly active <2400rpm with any torque requirement then whenever you cruise along leasurly at 80kph in top gear on a flat road it would be running. It wont be. Hook your BLG up to VAGCom and you will see what I mean.
What significant differences there are between the BLG and CAV engines? For one the latter has a more modern ECU. Beyond that I dunno.

PS.. mine has the squeal these days and it does not bother me a bit.

Logger--

your detail of the engagement of s/c below 2400rpms is exactly what my understanding was.

However I am sure I read somewhere that the s/c can be active ABOVE that 2400 threshold when required.

Does this mean both s/c AND turbo are cranking together at some
points? What would that (y torque value?) requirement be??

OR- gear selected (in manual mode or 6m) is too high for the turbo to
cope by itself so the s/c gives a helping hand?

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Originally Posted by MariusGT

Logger--

your detail of the engagement of s/c below 2400rpms is exactly what my understanding was.

However I am sure I read somewhere that the s/c can be active ABOVE that 2400 threshold when required.

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Yes you are quite correct. It can run above 2400 and up to 3500 which corresponds with the SChargers rev limit of 17,500 rpm. My reference to the 2400 was simply to clarify a misconception about when it runs in this band.

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Originally Posted by MariusGT

Does this mean both s/c AND turbo are cranking together at some
points? What would that (y torque value?) requirement be??

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YES. The Turbo will always be spinning while exhaust is passing through its turbine however it needs certain amount of exhaust pressure to produce boost. Supercharger meets this brief gap by rapidly coming online, boosting the engine which in turn boosts the turbo which takes over from the supercharger. Thereby significantly reducing boost lag and allowing for boost at much lower revs than the turbo could achieve.

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Originally Posted by MariusGT

OR- gear selected (in manual mode or 6m) is too high for the turbo to
cope by itself so the s/c gives a helping hand?

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Yeah I expect it would run in a tall gear when there is a high torque demand. Not sure what the actual torque figure is though and it will only be an arbitrary ECU torque in any case. This y value would probably be a curve.

Just been advised by VW here in the UK that a resolution has now been found to the squeal problem. They have advised me to contact my local dealer asap who will fit new parts under warrenty - Did'nt say what parts but will find out tomorrow when I book the car in.

Waterpump replacement is what they did for mine this week.

So just to clarify because I haven't read the entire thread but I am interested here...

The squeal is caused by the waterpump and replacements of that is the solution.

But this is different from the 'other sound' which is caused by the solenoid engagement the supercharger and there is still no solution for that issue.

Is that right?

The "other" sound is considered normal so perhaps no solution in being sought.

The supercharger solenoid and clutch is attached and integral with the water pump. Both sounds emanate from this same area. One, the "Squeak/Chirp" is thought to caused by the clutch material, which I understand has been changed on the new waterpump. The second noise, the "clicking" sound, can occur on solenoid disengagement. "When the magnetic clutch is switched off, three leaf springs pull the friction plate back to the starting position. Due to the high forces, a normal “clicking” of the magnetic clutch can occur".

I am not sure how prevalent the second sound actually is on the MK6. It predates the CAV engine and occured on the MKV BLG. So one would think they had already made mods to the WP clutch, prior to the latest fix to minimise its occurrence.

The "Squeak/Chirp" seems to be more common. I get it on my car. But not the clicking.

It will be interesting to see if you get a new waterpump too Kriss.... and if they roll it out as a warranty fix for the rest of us who are effected.

Thanks logger :)

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Originally Posted by kriss60

Just been advised by VW here in the UK that a resolution has now been found to the squeal problem. They have advised me to contact my local dealer asap who will fit new parts under warrenty - Did'nt say what parts but will find out tomorrow when I book the car in.

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Yes it will be interesting to hear how you get on in the coming months.

In Germany and UK, factory build post pump change new Scirocco 1.4TSi's (about Wk04/2010 build complete onwards) are reporting the "chirp" earlier, as early as 300 miles from new!

Replacement pumps fitted with the new modified clutch are reporting at about 1,000 miles.

This is the CAV type engine with the new pump: 03C 121 004 J, a new version of "J" reputed not to squeak. (VW haven't changed the part number!)

I somehow think VW have not solved it yet!

C.