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Finally getting around to pulling off the intake and replacing all the disintegrating vacuum lines. I had planned ahead and bought all the required parts a couple of years ago. I also bought the little electric solenoids that have the vacuum lines attached to them to replace more as a precautionary move since I had the intake off anyway. Everything was going well until I went to replace the solenoids and saw that the electrical connectors were different. My 93 called for #11741742711 but what I have on my car is #11741277974. The only difference appears to be the connector. Researching the 11741277974 the only E34 I can find that uses it is a E28 524TD. I hate to reassemble everything without replacing these solenoids so will make a call to my parts provider this morning to see if the 874 part is still available without a lengthy wait. Just wondering if anyone else has experienced this.





 

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i did this a couple years ago to my 3.8, my parts guy said the older connector style was NLA, so i got the new style, plus the correct connector. I'll try to search for the part number of the connector, or if i have a spare. I remember seeing one in my random box of extra parts.
 

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I talked to the parts guy and he said the original part number was still available but would be coming from Germany so I returned the newer plug in style yesterday. Parts guy said the original still shows up as being available for the 524TD. Now will have to wait a week or so to see what, if anything, shows up. While I was disassembling I found that the vacuum line going to the fuel pressure regulator was cracked and dry rotted and the line going to the idle air pump was open and not connected to anything. So, expecting some positive changes when everything gets reassembled.
 

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This part is the solenoid which when opened allows vacuum from the manifold to operate the actuator on the intake air box (item 10 on the diagram).
On the 3.8 the signal comes from the Engine Management Computer (DME).
On the 3.6 the signal comes from the dedicated Control unit.
 
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This part is the solenoid which when opened allows vacuum from the manifold to operate the valve on the intake air box (item 10 on the diagram).

On the 3.6 the signal comes from the dedicated Control unit.

Interesting. Where exactly is that dedicated control unit located? Also the solenoids have something to do with the air pump since it has a line going to it.
 

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On the 3.6, I believe that the Intake Air Control Module (Item A6006 in the Component Location Chart and is also known as the Resonance Flap Control Unit) is located in the E-Box on the RH Rear side of the engine bay - same box as the DME and can be found beneath the three relays between the Motronic (DME) Control Unit and the SRS Control Unit.
See the attached document which gives a guide as to system functionality and the connections.
 

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I stumbled upon this thread and wanted to follow up in case someone else finds it too.

My intake resonant flap was not working so I started looking at the schematics and diagrams and found determined the problem was likely either the ECM or the vacuum solenoid. Upon testing the solenoid does not work. It turns out the part number referenced above ending in 974 appears to be the same as part number end in in 973 from m10 powered 318i's vacuum advance system with the correct connector. This part number is 11741277973 and reference on realoem here RealOEM.com - Online BMW Parts Catalog

I found one and this solenoid seems to be working correctly with 12v applied. For future reference and as indicated above, the part number was changed with a change in connector. The new connector has the ev style (think fuel injector) 2 pin connector instead of the round connector found on the s38b36 vacuum connector. Here the replacement Vacuum Control Valve

To avoid wiring harness modification, if you have problems with the solenoid, I would recommend retaining the correct part number or going to the 973 part. I have not got the car back together to verify but they look the exact same so I suspect they are interchangeable if you can't find the 974. You can currently getthese from ECS tuning but they may get harder to find in the future where you would have to switch the updated part with different connector.
 

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To close out my last post, I have installed the 973 solenoid and now have a functioning resonant flap that actuates at start up. It doesn't appear to have any differences from the 974 part number and is a direct plug and play replacement if you need to find a correct solenoid and can't find the 974 part. For those junkyard scavengers, keep an eye out for early e30 m10 powered 318i models with vacuum advance where a spare solenoid may be waiting for you on the hvac/blower fan cover on the firewall. Image below of solenoid and image of 318i vacuum advance system( with 'VASV') which is similar to the s38 resonant flap actuation process. Note the vacuum lines use different ports than those used on the s38 solenoid.



 
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