D5 (D5244T to 2005) ECM-6805 only when the engine is cold

[krist2an]

I'm having the famous ECM-6805 error code with my 02 D5 V70. I've done numerous things already:
Replaced the intercooler (old one was leaking)
Replaced the front engine mount (again, leaking)
Replaced the turbo intake pipe (old one had gone soft)
Cleaned the MAF sensor.

The thing is that the error and limp mode only come when the engine is cold. I hooked up my VIDA and what's odd is that when the engine is cold, the VNT opens up 100% all the time, but when warm, it only opens ~70% max (according to VIDA). However, when the engine is warm, it does feel a bit sluggish. Could it be caused by sticky vanes?

[Dancake]

Sticky turbo vanes are the most likely cause. The best way to check is with a vacuum pump/Mityvac. The vacuum pressure is almost always enough to overcome sticking vanes at idle, but the problem comes when you're boosting. The ECM controls the turbo control valve to reduce vacuum as you accelerate. The diaphram within the vane actuator then struggles to overcome the sticking vanes.

Using a handheld vacuum pump, put the actuator under full vacuum. It should move freely without sticking, though it might stick if the vanes are really clogged. Once you release vacuum, the actuator should return to its normal resting place. If it sticks or slows down on the way back, the most likely cause is carbon build up on the vanes. You might also get a rasping hissing noise when boosting, coupled with a dump valve sound coming from the airbox area when you let off the throttle. Sticking vanes can give similar symptoms to a vac leak.

[Rooster]

My xc90 does it sometimes from cold if i give it a boot full from cold, eg pulling out of end of street, but will only do it that once if it does it at all,

There is a VNT control valve behind the elbow intake pipe on front of engine that causes issues but there an absolute fortune for a new one, about 165 quid

[davebb]

Originally Posted by Rooster

My xc90 does it sometimes from cold if i give it a boot full from cold, eg pulling out of end of street, but will only do it that once if it does it at all,

There is a VNT control valve behind the elbow intake pipe on front of engine that causes issues but there an absolute fortune for a new one, about 165 quid

Hi or cheaper then £50 if you use a tcv made for a VW and loom to convert plug,
Dave