turbo question?

[watteee]

Hi i have a 98 a6 2.5 tdi,i can hear my turbo whistle at about 1500-2000 rpm,however does anyone know if it stops spining at a certain amount of rpm,its just when i listen with the window down i can hear the whistle but it stops spinning at 3000 rpm as i can hear the whistle stopping as if ive dipped the clutch and changed gear but ive not im still accelerating,i was thinking it was some clever way of saving fuel and only using the turbo when needed,i wish it kept on going above 3000 rpm as i feel these heavy beasts could do with extra oomf as they are pretty sluggish.

[Tobes49]

You should have boost through the rev range till the red line,

The turbo will spool up about 1500RPM in this case, reach maximum boost about 2000RPM, peaks slighty then settles and should hold stable to the red line.

Sound like you might have a problem, Would check the air flow meter first (MAF).

[watteee]

if the MAF was faulty wouldnt i get other problems.my MAF went on a previous car i had and it would cut out and then run fine then cut out again,the audi seems to drive perfect no flat spots no non startin,drives really well in fact,no loss of power,the only symptom is the whistle from the turbo stops at 3000rpm but it still accelerates after that at the same rate as when i could hear the whistle.

[kite]

Sounds like the turbo is working just stops whistling when it has reached max boost !

[ELSA_MAN]

At low revs and full throttle the boost control will be boosting the turbo flat out until the turbo achieves the desired boost level. The boost control will then back the turbo off by adjusting the angle of the variable veins in the turbocharger. This is prob when the noise goes away. Sounds normal to me.

[watteee]

mayde so,im thinking of re mapping it after the new year,compared to the other audi i had (1.9 tdi 130) its like driving with the handbrake on.

[kite]

Is it the 5 pot or the V6.

Early V6 was only 155BHP I think, thats not a lot for a big barge !

[watteee]

its the early one 155 bhp,too slow!! i think a remap will sort it though,ive called a few places that do it and they say the difference is awesome.

[Tobes49]

[ QUOTE ]

if the MAF was faulty wouldnt i get other problems.my MAF went on a previous car i had and it would cut out and then run fine then cut out again,the audi seems to drive perfect no flat spots no non startin,drives really well in fact,no loss of power,the only symptom is the whistle from the turbo stops at 3000rpm but it still accelerates after that at the same rate as when i could hear the whistle.

[/ QUOTE ]

Best thing is to borrow VAG-COM and log MAF and Boost pressure readings, Post them up and this will say if you have a problem.