2008 v70, D5 185hp, ECM-P029900 underboost, limp mode

[frenchfarmer]

Hello,


I have a 2008 v70 D5.
And my car is going into limp mode for a while. And the only code VIDA is given is ECM-P029900 underboost.
I changed a few parts, and the problem is only partly solved..
I've changed:
-Turbo ( small part of the turbine missing,gives 250kpa now)
-Turbo actuator
-EGR is deleted by a tunner+ blanking plate
-Boost sensor
-Intercooler (there was a small crack).
I can't find any large leaks in the admission, so the leak, when there is a leak, must be very small.

Is the problem due to boost latency or not enough pressure? I know vida gives the codes when the boost pressure is 15kpa under de desired value for more than 10s.
Is de code stored for an other reason than just boost pressure difference?

The blue mark is where the car goes into limp mode, is totaly random when you accelerate suddenly. Just before the car works perfect for 15min, and after the DTC reset the car worked fine again for 15min.



Thank you for your help!

John

[Kev0607]

Check for any split hoses, particularly the intercooler hose.

[Cossie7]

If you've installed a new actuator on a 2008 it should be an electronic one...

Have you carried out the actuator calibration through diagnostics?

It will work without but can experiance the same issues you have here as the ecu needs to learn the new actuators characteristics and travel.

I put one on mine and had underboost issues (once I'd finally figured out why my actuator wouldn't actually work)

You also say the motors been mapped, does the actuator work? If you go on live data do you have waste gate actuator duty cycle or is it showing 0%?

I only ask as mine had compound issues, the original actuator was fault so I changed it but at the same time mapped the car. I originally thought the new actuator was faulty aswell but hen notice my actuator duty cycle was stuck at 0%.

After a very lengthy process of pinning out all the wiring and looking at everything it turned out during the map when the egr was turned off it effected the request for boost from the egr resulting in 0% duty cycle even though on live data the car was showing the correct "desired boost pressure"

[Cossie7]

Actually, looking at your graph ut may just be the calibration if not done as you desired vs actual is pretty close as mine just flat lined.

May be worth cleaning the TMAP if calibration doesn't work or as kev0607 says have a look for boost leaks

[frenchfarmer]

Thanks everybody.
I re calibrated every piece of electronic on the engine/turbo system.

But it seemed to be the plastic tube after the turbo under the engine, it had a very very small crack. But at full pressure it still leaked quite much air.
I did a quick temporary fix with a piece of rubber and an hose clamp, and till now it worked!
So i just have to order a new tube.

But still, is the delay between the turbo pressure and the desired value normal? Do you experience de same on your cars?

[ShaunKaz]

Hi, Just on this I have the same problem P029900 I had to have a new head as aux belt got under cam belt and destroyed my cyclinder head.. since back together 4 weeks ago I have codes P00BD00 & P029900 Ive done a smoke test, vacuum test and a new MAF sensor as the car went into Volvo.. they even tried a TMAP but no joy.. Im reading this post as you calibrated the actuator do you think I need to do this?