Whistling turbo C220 cdi

[marm1te]

A couple of weeks ago I fitted a microprocessor diesel chip box, to smooth out acceleration and look for better cruising! Absolutely delighted with it, car immediately felt better, smoother, fuel economy +4mpg (measured manually not just on trip computer)! Set box on 5 out of 8 as that felt just right. Really good - car felt brilliant, never run so well. No engine mgt lights, no smoke, no noises, great! A week later decided I would clean maf sensor which went fine, obviously used proper cleaner, all good, no issues! But since doing this I.e MAF, turbo is making distinct spooling noise, high pitched whistle. Car still feels great, again no smoke, did 450 miles yesterday at 53mpg - very smooth miles, had a blast of acceleration a few times (m6 toll booth exits) no problems at all. I turned boost on tuning box right down - no difference to turbo whistle. Checked air hoses and air box - all hoses look fine, nothing seems amiss. Questions (a) should I be concerned (b) is this a likely result of cleaning MAF (b) tuning box or something else. As I say car feels perfect but obviously I'm thinking oh no is my turbo going to blow, have I done something bad! I don't need lots of bad words about tuning boxes, as I say car feels great. Just views on turbo and whistle really? Car has done 84k. Thank you in advance!

 

[LittleG]

Mine has always made a noticeable whistle with a little surge of air on gear changes. Mines nearly 100k ahead of yours though.

 

[marm1te]

Thanks Little G - I see loads of VAG reports of turbo spool but few Mercedes and no C220s.

 

[vealige]

As above some turbo cars are more audible then others. Both our Vag diesel's you can hear the turbo spool when on boost this got noticeably louder once re-mapped nothing wrong with the turbos mind.

 

[marm1te]

Just a quick update on this, I still felt something must be amiss for the whistle to have developed so quickly and eventually found that an orange rubber seal air induction side of the turbo had perished and presumably I had finally seen it off when moving plastic duct from air box to turbo. The seal makes sure the intake us air tight. Tried to buy Part on line, quoted £48 ouch! Went to MB £3.42, job done, whistle gone!