"Black Box" on Exhaust System?

[bootes]

I bought my '71 280SL back in '02 from the original owner and was given a lot of receipts, notes and letters re the history of the car. One of the notes I come across periodically... but have never asked anyone about relates to a so called "black box." The note was given to various mechanics over the years apparently and states: "Do NOT reconnect the "black box" on the exhaust system for pollution control; it has been disconnected since 1973 for a good reason; it destroys the drive-ability of the car."

Anyone know what she is referring to?

Thanks!

[jeffc280sl]

I think she is refering to a pair of black boxes located near the battery.  They are emissions related and control when tiiming is advanced or retarded as well as some other functions MB used to reduce emissions.  Many have disconnected the boxes including me.

[jeffc280sl]

Search under the term "2 way valve"  for more info.

[bootes]

Thanks Jeff for your replies.

I have located the "black boxes."  They appear to be connected although I'm not exactly sure how you determine if it is disconnected. One line is to the distributor and one line is to the exhaust manifold. It looks like the power source may lead into the firewall. 

What are the steps to disconnect this? Any repercussions? If I do disconnect, is there marked improvement in performance?

Thanks!!

Rick

[jeffc280sl]

http://www.sl113.org/forums/index.php?topic=12238.0

Read this thread

[bootes]

Thanks but I guess I'm missing something. I'll have my mechanic look at it. I simply came across a note from the original owner stating that the black boxes  (disconnected since 1973) should not be reconnected as it cuts down on performance but from what I can tell they have been reconnected. Is it as easy as disconnecting the hoses from the manifold and distributor or does that cause problems with timing?  Do I disconnect the power source? Maybe I just leave it as is.

[jeffc280sl]

Bootes,

Based on the info you have provided I can't say what you should do about the emissions system.  At least now you have some documentation.  If you have time you can try and trace wires or ask your mechanic to do that.  With mor information we should be able to help out.

[bootes]

thanks Jeff,

how did you disconnect your system?

Rick

[Peter van Es]

Are you talking about this: http://www.sl113.org/wiki/Electrical/EmissionControlSystem or about http://www.sl113.org/wiki/Fuel/VaporTank which is also a kind of "black box".

Also read the following topics:

http://www.sl113.org/forums/index.php?topic=10066.0
http://www.sl113.org/forums/index.php?topic=6484.0
http://www.sl113.org/forums/index.php?topic=12238.0
http://www.sl113.org/forums/index.php?topic=10806.0

All found with a quick search on "emission control"

Peter

[Naj ✝︎]

Hi, Rick,

I would only disconnect the 2 pin plug on the vacuum valve mounted on the same bracket as the black boxes.
This would disable the retard function on the distributor but still operate the fuel pump solenoid (on the IP) which stops the exhaust popping on decelleration.
Disconnecting the vacuum pipe at the throttle body or distributor is going to cause air leak issues.

naj

[bootes]

Peter, thanks for the links.  I have reviewed these.  I am referring to #4 and #5 in this link:  http://www.sl113.org/wiki/Electrical/EmissionControlSystem  I came across a note from the original owner that these "black boxes" had been disconnected since 1973 and to not reconnect as it would ruin the drive-ability of the car. It appears to me that a mechanic somewhere along the line has reconnected. I have been trying to determine how to disconnect or proper way to disconnect.  But from what I'm reading, timing may be affected and I would like to know, simply, how to disconnect (and if it's worth it? does it, in fact improve drive-ability?).

Naj (thanks for your reply as well) suggested disconnecting the 2 prong (#9 in the link above) which I've now done but have not been able to test due to inclement weather here in Pittsburgh.

Any other comments on disconnecting this and how it affects drive-ability would be much appreciated!

Thanks,

Rick

[jeffc280sl]

Naj,

It's my understanding the fuel shut off solenoid causes the popping noises on decelleration.  I have this solenoid and the 2 way valve disconnected on my car.  I use the 123 distributor.

[bootes]

Jeff,

How did you disconnect the 2-way valve? Did you do so by disconnecting the 2 prong going into the vacuum attached to the black boxes (as Naj suggested)?  I don't ever remember "popping" on deceleration but can you explain how you disconnected the solenoid as well? Thanks