[robnitro]

Good luck with that, it's not going to be easy if the dde does whatever it wants independent of your control system. Some guys tried to do that with with the tdi, using the electronic actuator from the 2260vk and it wasn't feasible with the way the ecu works.

[torqueisking]

The DDE shouldn't know the difference if the control system results in operation within the DDE expected parameters and the pressure converter impedance is mimicked (as seen by the DDE).

Thanks for letting me know about the 2260VK actuator. I'll take a closer look at the specs for potential use on the M57.

[Yozh]

People, please also make sure your vacuum lines are routed and connected correctly. One mixed connection can throw The whole system for a loop.

[shnaggs]

Yozh,

Should the vacuum system hold a certain amount of vacuum once the vehicle is shut off? If I T into one of vacuum lines at the front of the motor, I get right around 26 In/HG and if I shut the vehicle off, I loose vacuum. If I had to guess, I would loose about 10 In/HG in about 5-6 sec. Is this normal?

My symptom is, sluggish low end. My HP turbo definitely works, but I feel I need to press the accel pedal a lot further than I used to and when the car starts to accel, its not as brisk as it once was. Once the LP turbo comes on line its just as its always been.

[grantbp]

Hi,
First a great post for the vacuum system.
I am troubleshooting a low pressure error and everything that should be holding a vacuum is and the all actuators moving correctly.
I highly suspect one of they pressure convertors is faulty.
At idle speed i connected to the output port from the pressure convertor.
The convertor going to the vacuum box read around 266 millibar.
The convertor going to the waste gate read zero vacuum.

I suspect the pressure convertor going to the wastegate is faulty??

[Yozh]

Shaggs, where are you teeing off? If before the vac box, you should be loosing vac on shutdown. Have you checked the turbo switchover behaviour.

[Yozh]

Originally Posted by grantbp

Hi,
First a great post for the vacuum system.
I am troubleshooting a low pressure error and everything that should be holding a vacuum is and the all actuators moving correctly.
I highly suspect one of they pressure convertors is faulty.
At idle speed i connected to the output port from the pressure convertor.
The convertor going to the vacuum box read around 266 millibar.
The convertor going to the waste gate read zero vacuum.

I suspect the pressure convertor going to the wastegate is faulty??

At idle output of the wastegate pressure converter is zero. That means your wastegate is closed.

[grantbp]

is there a way to test the pressure convertors??

[Yozh]

Originally Posted by grantbp

is there a way to test the pressure convertors??

Yes. You can check resistance. Or check them during their operating state visually or through ISTA. However, they are cheap enough that if you have any doubts, you can just replace.

[torqueisking]

Originally Posted by grantbp

is there a way to test the pressure convertors??

https://www.e90post.com/forums/showthread.php?t=1589166

[nicklockard]

Originally Posted by torqueisking

Been thinking about this too. I am building a pressure convertor feedback system for my 335D as a first step. The feedback will be at the output of the PC. This will also allow me to adjust system gain and offset electronically.

Second step will be to move the feedback to the output of the vacuum actuator. I was thinking about using a slide potentiometer but heat, resistance tolerance and resistance linearity could be problematic.

I also would prefer to do away with the vacuum actuators entirely and use linear actuators but heat and cost likely wouldn't make this approach viable.

What about this high temp stepper motor to replace vacuum actuators and provide feedback? With a programed micro-controller, perhaps it could get command signals directly from the ECU...I don't know, just throwing it out.

https://www.radwell.com/Shop?source=...BoCr9gQAvD_BwE

It has 2.21 ft/lbs torque. For an appropriate sized lever arm, it should be able to generate ~7-9 lbs linear actuation force with sufficient throw. That sounds close to what ours require.

[robnitro]

Nick, they're nice motors I've seen on cnc machines but due to size, placement may be an issue.

[torqueisking]

That high temp stepper motor looks very capable but I have to go with robnitro's perspective on this one. There isn't much room around the flap arm and inner fender.

I think the 2260VK type actuator robnitro suggested could work but it appears as though a level type linkage would need to be added to achieve the excursion required by the M57 bypass flap. AFAIK, the 2260VK type actuators appear to be designed to actuate the vanes in a VNT Turbo which require less excursion. Wish I had time to put it all together!

[nicklockard]

Originally Posted by robnitro

Nick, they're nice motors I've seen on cnc machines but due to size, placement may be an issue.

It's a NEMA23 frame size or 2.3" square, smaller than the waste gate vacuum actuator. Need to bend up a mounting bracket for it and maybe mount it where the existing vacuum actuator is and modify the linkage assembly...

[RL18]

Yozh is it just me or are all your pictures and great information not showing up now?

[Yozh]

True. A rewrite is due.

[Yozh]

True. A rewrite is due.

[Coastcanuck]

Hey guys, just adding a little something about the system. The pressure relief valve for the LP turbo can stick in the open position. It's somewhat common over in europe. Only code I got was 4530. I replaced my vacuum lines, pressure converters and the controller for the pressure relief valve. Also installed a forge motorsport hose to no avail. Shoved a scope up from the intercooler side to see the flap and found in stuck open. Tried to manually free it but no luck. New piece on the way now.

Symptoms of this are no boost until ~3500rpm

EDIT: Ended up not needing the new piece, was able to heat up the arm (I used oxygen acetylene very gently, would probably start with propane or something smaller if you're not comfortable with torches), and then lubricate, moving freely now. Removed the A/C compressor and bracket, as well as the intercooler and charge pipe to get access. I really didn't want to deal with heating the aluminum and risk melting, and there was serious corrosion on the bolts holding the pressure relief valve in place.

[RL18]

Originally Posted by Yozh

True. A rewrite is due.

Not to keep pestering you but did you ever get around to a rewrite?

I really would like to see the diagrams of where the lines run to just to make sure they go back in the right place. Thanks

[Yozh]

After the 25th we will have a video done. For now, there are diagrams on realoem you can follow.

[RL18]

Originally Posted by Yozh

After the 25th we will have a video done. For now, there are diagrams on realoem you can follow.

Perfect! Thank you Yozh

[bmwdiesel]

I have checked vacuum hoses and changed those that didnt look good, but now when I start the car the brake pedal is stiff, which should be sign of no vacuum, where before it was fine. all hoses are connected good and since I dont want to take out intake for nothing, I am trying to find out if you can actually blow into the hose that connects under the right sight of the intake that is pictured below. I am using the hose number 5 that also connects to the pressure converter and that is air tight to the converter but I can blow the air into this 5 nipple connection opening. it is little resistant, but I can blow it. I tried with a smoke if there is a hole but didnt see it coming. can someone confirm whether this should be air tight or whether you can push air there that would mean somewhere is a hole? I understand that vacuum is from vacuum pump that is the thick hose on the bottom and the 5 nipples introduce the vacuum into the other parts of engine. If it should be air tight, I know some component is leaking, but maybe some air can be pushed to the vacuum pump, or swirl flaps electric valve? if anyone knows would be good, because I am doing this 5 days already