D5 with low boost below 2000 rpm

[AXB]

Hi

S80 2006 2.4 D5 aut. (300' km). The issues are:

1. Low boost and torque below 2000 rpm (max 1.5 bar/22 psi). When passing 2000-2100 rpm it almost immediately increases to 2.1 bar/30 psi, and it continues to pull fine until the redline.
2. Slow to pick up boost when flooring it above 3000 rpm (meaning >3000 rpm and then flooring it). Occasionally in this scenario with "Engine service required" in the dash, and ECM-6805 stored (note: sometimes the message in the dash is shown without any codes stored on the ECM)
3. I only had it for 3 years and don't know what to expect, but I think it always had a bit low torque below 1800-2000 rpm, but getting slowly worse.

What I have done so far without any effect what so ever:

• Replaced VNT-regulator (the solenoid valve on the motor block).
• Pressure tested the intercooler and tubes with 1 bar compressed air. No leak.
• Checked the friction of the vanes on the turbo. They move with feather-light finger force.
• Blocking feed line to the engine mounts solenoid (one engine mount was leaking, but the flow is nevertheless cut off at 1100 rpm, so shouldn't matter?)
• Checked vacuum system for leaks.
• Driven the engine hard. I also drive it quite hard generally with lots of full throttle, and 9/10 rides are more than 100 km.

Some additional info:

• I measured the vacuum from the pump while driving and it's varying a bit, especially when the VNT-regulator is at roughly 50 %. I think it is because the VNT-regulator consumes a lot of vacuum to always adjust the turbo vanes?
• Gearbox not the best, but have done its job for the past 50' km.
• Never observed black smoke.
• Normal fuel consumption (measured: 50 MPG, but the dash is indicating 62 MPG)
• Cold or warm engine makes no difference.

I have VIDA. Any suggestions on where to continue the troubleshooting?

[camturbo]

Have you checked the turbo actuator? Look up sirobb on youtube as he has a video testing the vacuum actuator. You may have done that already. Dont know how often they fail or even do. I believe the engine mounts share the same boost lines as your turbo. Also boost pipe on turbo inlet side can go soft as well. Apart from that I dont know. Hopefully someone will be able to help you further,you seem to know your stuff for the tests you've done so far

[barrybritcher]

its probably about right?

brochure says max torque from 1750rpm

[eagle58]

Originally Posted by barrybritcher

its probably about right?

brochure says max torque from 1750rpm

My C70 D5 Geartronic is sluggish off the line - sometimes it's a bit disconcerting.

When I drove a manual car this was never the issue as I'd rev up, drop the clutch and off we'd go!

I've started to use Cetane as an additive and I'm not sure if that helps or not.
Higher revs,(perhaps it is 1750 rpm) means it then takes off like a rocket.

I don't want to wreck the gearbox so I don't rev up in neutral and then stick it in drive so I guess I've adjusted how I drive.

[richieski]

Originally Posted by AXB

[*]Blocking feed line to the engine mounts solenoid (one engine mount was leaking, but the flow is nevertheless cut off at 1100 rpm, so shouldn't matter?)

I think it does matter.
I just found mine leaking so blocked them off also i cleaned out my egr too. Cars feels so different now. (like it can breathe, i now just feather the throttle whereas before it was foot down)