X5 40d reduced power *no relevant DTC codes*

[lux_tv]

Hi everyone,

Having a few dramas after doing a Liqui moly pro-line DPF flush (through oxygen sensor):

1) once DPF flush was done and regeneration was complete went on the freeway to ensure regeneration was complete- after driving for a while engine went into limp mode with error stating EGR valve blocked (and a few others as a consequence)

2) cleaned out EGR valve (was blocked) and did an intake clean using threebond diesel conditioner- remaining error after this was 4530- charging pressure too low on high-pressure stage (small) turbo

3) followed forum instructions as to troubleshoot and swapped the high and low stage pressure converters- this has cleared the code but the engine is still running with no boost. This to me would suggest the pressure converters are ok (or a massive coincide that both have gone at the same time)

I cannot see any vacuum leaks and the red intercooler pipe is clean (no oil), the other intercooler pipe seems fine. Vacuum pressure to group of sensors (from vacuum pump) is 88mmHg, from high pressure converter is 45mmHg and from low pressure is 38mmHG (this was initial suspect that could have been faulty).Any thing else I should be checking/double checking?

Thanks in advance,

Luke

[335dsleeper]

Do you a total lack of boost or is the smaller turbo just not spooling?

Go wide open throttle and see if it feels normal over 3k Rpms, when the larger turbo kicks in. If it does, the changeover valve or vacuum line to it might be the issue.

There is also an electric valve. This part can cause pressure converter like failures/ symptoms.

https://parts.bmwofsouthatlanta.com/...747810831.html

[lux_tv]

Thanks for the suggestion, took it for a drive and when I went over 3000rpm the engine warning light came on, codes came up that were 4530 (usual error with this), 48f8 (charging pressure actuator not present) and 3ff1. Doesn't feel like it has power anywhere, I'm stumped!

Checked the output vaccum pressures, electric valve reports 0mmHG at idle, high pressure converter is about 500mHG (seems correct) and low pressure converter is about 35mmHG (also seems correct).

[lux_tv]

Originally Posted by 335dsleeper

Do you a total lack of boost or is the smaller turbo just not spooling?

Go wide open throttle and see if it feels normal over 3k Rpms, when the larger turbo kicks in. If it does, the changeover valve or vacuum line to it might be the issue.

There is also an electric valve. This part can cause pressure converter like failures/ symptoms.

https://parts.bmwofsouthatlanta.com/...747810831.html

Missing total lack of boost