XC70: Engine D5: Boost drops for a while after 3000 rpm

[macintyre]

Hello

I noticed some sloweness in acceleration on my xc70 D5 awd 215hp.
Recordings of boost gave me some strange graph (attached). I can see a sudden drop in revs when the tachometer reached 3000 rpm, followed by an increase again. (The pedal was in the same position throughout, just before the kick-down, the entire time. 1400 rev - 4400 rev). I did test more then 5 times in different days.

I cleaned MAP and TMAP after that, but can't see any difference.

Also, MAP sensors readings, with ignition on, attached.

Any suggestions what else could be wrong? Or, maybe, such lug in boost is expected for D5 bi-turbo?

[apersson850]

Not that I've created any graphs, but I've not felt anything that would be coherent with such a boost drop. Mine is a D5 230 hp/470 Nm version.

[macintyre]

Originally Posted by apersson850

Not that I've created any graphs, but I've not felt anything that would be coherent with such a boost drop. Mine is a D5 230 hp/470 Nm version.

Thanks for this information. I have just ordered another boost sensor, will try to replace soon.
For me it is visible on tachometer (exactly when it reaches 3000 drops to 2800 and starts rising again, like a gear shifted) and by reading boost values. It can be felt better if driving slightly uphill.
Only visible on chart if driving downhill.

[Tannaton]

Check the reading from the catalyst and dpf temperature sensors, if these are high or not sensible (open or short circuit sensor) it will wind back the boost but doesn’t always throw an mil lamp.

[macintyre]

Originally Posted by Tannaton

Check the reading from the catalyst and dpf temperature sensors, if these are high or not sensible (open or short circuit sensor) it will wind back the boost but doesn’t always throw an mil lamp.

Hey,
How can I check if they are good?
I took some logs on cold:

[apersson850]

As far as I understand here, you see this at the same engine speed each time?
Otherwise a "slap on your fingers" from the anti-spin system could cause something similar. But then it would not be always and not at the same engine speed.

[macintyre]

Originally Posted by apersson850

As far as I understand here, you see this at the same engine speed each time?
Otherwise a "slap on your fingers" from the anti-spin system could cause something similar. But then it would not be always and not at the same engine speed.

Same engine speed every time 3000rpm.
3rd gear in manual mode.
And boost graph absolutely the same every time.
It looks like big and small turbo not synchronized, like some valve is opened not in appropriate moment. But there are no errors, and all sensor data looks good.

Most recent graph. I recorded data a few days ago while driving uphill. Red line is RPM.