[nobrakese28]

Hi guys, I know this is the 335D forum but I know the vehicles are very similar and a lot of expertise and experience is shared on this side.

My wife was driving the X5 yesterday when the low fuel light warning came, the vehicle then proceeded to through the "engine malfunction, reduced power warning". She thought it was just low on fuel, so she pulled over and called Triple A. They put a few gallons in and she headed for home, the "engine malfunction, reduced power warning" came on again when she heard a noise she described as "an airplane landing" and vehicle began to lose power.

She was able to make it home safely. So I started the car and went around the block and the car has no power, it feels like the turbo system is not boosting at all. I scanned the codes and got three, two of which are for glow plugs, and the third was the P0299 code.

I dug into the engine and could not find any obvious boost leaks or vacuum leaks. I did a lot of reading and researching on how the turbo and vacuum system works and have a better understanding of the system now but I was hoping someone could chime in.

If there was a major vacuum leak would that affect the braking system? The breaks seems to function normally.

I also verified that the diaphragm between the turbo stages is working, the video by Alex Rodriguez was very helpful.

I understand that there are two pressure converters and an electric vacuum valve. Since the turbo diaphragm is working I believe I can eliminate the 11658509323 pressure converter on the firewall side.

Could the second pressure converter or electric valve (11747810831) be preventing the motor from boosting?

Thanks,

Marco

[dmanb2b]

Hey Marco,

Were you able to confirm your red boost hose is in tact? Also look for any greasy or sooty areas, especially the dpf pressure differential sensor hose.

A vacuum leak will not impact your brakes

[nobrakese28]

I plan on running the vacuum checks on the wastegate and compressor crossover diaphragms tonight. I will disconnect and follow the red hose from the crossover to the electric valve.

So failure of the hoses on the DPF sensor could cause a lack of boost?

[dmanb2b]

Originally Posted by nobrakese28

I plan on running the vacuum checks on the wastegate and compressor crossover diaphragms tonight. I will disconnect and follow the red hose from the crossover to the electric valve.

So failure of the hoses on the DPF sensor could cause a lack of boost?

DPF pressure sensor hose may put you into limp, but more importantly you want to check the red boost hose from Turbo to intercooler...It sounds like you have a massive boost leak. Try monitoring drive pressures with torque pro as well.

[Yozh]

p0299 = BMW 04530 code. It’s a fairly wide code. Anything blocking the exhaust or leaking on the air side can be the reason. Most often it’s the boost leaks or failures within a vacuum control system. Vacuum lines, broken nipples, failed pressure converters, etc can cause the issues. Of curiousity is the airplane landing sound. Have you checked your exhaust pressure sensor feed line. Do you smell raw diesel exhaust?

[nobrakese28]

Thank you for the responses so far, I dug into the car further yesterday and removed the vacuum reservoir with sensors to get a better look.

I did not find any vacuum leaks, I tested the hose between the compressor crossover and electronic valve, I also tested the valve with 12v. Both seem to be okay.

I tested the compressor crossover diaphragm and it moves and holds vacuum (verified arm movement).

I then tested the large turbo actuator with the vacuum pump, arm moved and held vacuum.

I then tested the turbo wastegate diaphragm (I believe only the larger turbo has one), and this one has me wondering.....

I pumped it with my mightyvac and it held vacuum, but it would not make an audible noise when released. So my brother crawled under the vehicle while I pumped and released the vacuum pump, the wastegate arm is only moving about 1/8".

This does not seem to be normal, could the wastegate be stuck open?

Yozh, I read through you excellent write up on checking and testing the vacuum components, I believe you stated you should hear a mechanical click when it is released.

I believe the wastegate is normally closed at idle on turbo cars to allow boost to build. I know these cars are much different as they have two turbos.

Would a open wastegate on a low pressure turbo give me zero boost?

Thanks,

Marco

[nobrakese28]

I talked to the good folks at Malone/JR Tuning and they informed me that the turbchargers are quite robust and wastegate failures are very rare. The told me if I had any oil on the charge pipes that they are leaking, the one on the compressor side is soaked and full of oily gunk.

He also mentioned the hoses could look perfectly good but have a large gash.

The plan is to replace all of the vacuum lines I can access, and the ones that head under the manifold will have brass vacuum T's spliced in, I'll replace the remainder of the line when I pop the manifold off for the glow plugs and module. I also ordered the 0-rings for the charge pipes, which I will remove and inspect.

[robnitro]

Originally Posted by nobrakese28

I talked to the good folks at Malone/JR Tuning and they informed me that the turbchargers are quite robust and wastegate failures are very rare. The told me if I had any oil on the charge pipes that they are leaking, the one on the compressor side is soaked and full of oily gunk.
.

The oil in the charge pipes could be from ccv too, so I'm not sure how you can tell if it's the turbo leaking it or from normal ccv fumes?
I guess if your oil level was dropping faster than normal...

[Yozh]

I think it’s oil “in” vs. “on” the chargepipe. External oil means there is a leak. I vote for replacing the vacuum lines. Testing of pressure converters should be done at idle and then during driving.

[nobrakese28]

So I replaced all the vacuum lines that were accessible with the vacuum reservoir removed, where I could not replace (under manifold) I put in a brass barb.

I took the car and cleaned the engine to prepare for further investigation, rescanned the motor and got the same codes.

I decided to try and make the car boost, it appears I have no low end power, say from idle to 2800RPM, after that the car boost's and accels quite hard.

So it appears that the low pressure turbo is working.

I can see the large turbo actuator arm move when the car starts and slowly retract when the car is off (as it should correct?).

I tested the compressor bypass with my vacuum pump and can had my brother confirm the arm is moving.

Yozh, how can I test the pressure converters at idle and during driving?
I only saw the electrical resistance test in your write up.

What else could cause the small turbo from boosting?

Thank you.

[nobrakese28]

More vacuum testing with Mightyvac:

1) Vacuum Supply to Reservoir: 25 in of vacuum, holds
2) Vacuum Reservoir: 25 in vacuum, holds
3) Vacuum Supply to Pressure Converter 1: 25 in vacuum, holds
4) Pressure converter 1 to Wastegate:, no vacuum at idle
5) Pressure Converter 2 to Compressor Crossover at idle, no vacuum

Low Pressure Turbo Actuator retracts at idle, normal. This would send exhaust gas to High Pressure Turbo. This confirms the 2nd (closest to firewall) Pressure Converter is working.

Compressor Crossover does not move at idle, normal. Sending majority of air to High Pressure Turbo. Not sure how to test this, they are not simple 12v switches.

Re-tested the wastegate, holds vacuum, much harder to pump with Mightyvac. Makes no noise when released. At this point it is impossible to tell what state it is in. The DPF would need to be removed to view the wastegates from the rear.

I did test the wastegate switch, and it was operational. Not energized the wastegate circuit is at ambient pressure, when energized the wastegate is applied vacuum. Which would likely retract diaphragm and open the wastegate.

So I have no power below 3000RPM, which mean the high pressure turbo is not boosting. Would an open wastegate cause this?

[nobrakese28]

Removed intake feeds from large to small turbo, which requires loosening the mounting bolts on the small turbo. The small turbo is seized along with damaged impellers.

Just happy to have found the problem.

[nobrakese28]

So the is to remove all of the charge pipes and clean them along with replacing the engine oil. I will also remove the intercooler and degrease it to free any metal pieces from the impeller.

[Owen81]

I would replace the oil lines as well, there could be debris in there and they are very prone to leak later in their life anyway.

[nobrakese28]

Turbo replaced along with boost valves etc. Car runs great again.