Emission Control Stuff

[bpossel]

Hi All!

Those of you that have removed the emission control stuff from your 113's, what does that really mean?

1.  Disconnect (remove) the 2-way valve?
2.  Disconnect (remove) the speed relay, control boxes (black boxes)?
3.  Disconnect the 100 degree & 17 degree switches?
4.  Connect vacuum directly to the manifold
5.  What else?

How did this effect your timing?  Idle? etc?

Other comments?

Thanks!
Bob 

[abe280SL]

I'll another question to that...how does it differ on a 68 vs 69 vs 70 vs 71? I have a 68, is there anything worth disconnecting?\
abe

[Peter van Es]

Bob,

as I did not do the modifications myself it's very hard to tell you exactly what was done. However, I had a look and found attached diagram in the BBB. I have a 1970 280SL.

As far as I can tell:

• The two way valve (#9 in the diagram) and associated stuff (#29) are gone
• The speed relay and control boxes (#4 and #5) and associated terminal blocks are gone
• the 100 degree switch (#8) is gone and closed off with a bolt of some kind
• the 17 degree switch (#7) is still there but I could not trace the wiring. It may be disconnected
• #15 is still there but couldn't trace the wiring
• vacuum is connected directly to the manifold

I hope this helps, but you really should consult an expert rather than me!

Peter

[bpossel]

Thanks Peter!
Bob 

[JPMOSE]

Abe,

The 1968 USA model year doesn' have much as far as emission controls.  There is a Fuel Shutoff Value solenoid on the back of the Fuel Injection Pump (the lower of two solenoids).   This kicks in when the car is decellerating but often times is disconnected.   There's a Bocsh Speed Sensor Unit and Relay on the left side of the engine compartment (behind the ignition coil) that often fails and sometimes would cause the engine to stall by activating the Fuel Shutoff Value at too low an RPM.  The Speed Sensor Unit is around $800 from the dealer -- I can only imagine one is purchased for a 100 point restoration. 

Please see my post on '68/'69 emission controls:

 http://www.sl113.org/forums/index.php?topic=5177.msg32347#msg32347

[abe280SL]

Thanks, JPMOSE
abe

[jeffc280sl]

I have disconnected the fuel shutoff wire to the FIP.  Switches on the transmission (manual and automatic) are supposed to determine when the car is coasting and reduce unspent fuel emissions by enabling the fuel cutoff. Along with the wire feeding the fuel cutoff solenoid some of my switches are inoperable but that doesn't matter because the solenoid is disconnected.

I'm more familiar with the manual transmission version for 1970. I think its similar for the auto.   The black boxes contain rpm sensors and relays.  They are  designed so at certain rpm levels the distributor is supposed to advance or retard, can't remember which right now,  via the 2 way switch. Dan can speak much better about this than I but I think it has a marginal impact on emission levels and performance because any vacuum effect is overcome by the weights inside the distributor as rpms increase.

The 100 c and 17c switches utilize relays in the black box to activate the two way valve again.  The effect is to increase idle when the temp is above 100c and below 17c.  The 100c switch in effect tells the 2 way valve to change the timing which increases idle to help cool a very hot engine.  The 17c switch works in conjunction with the TTS to help warm a cold engine by stepping up the idle speed via the 2 way valve.  It works well when the switches work and the relay boxes do their job.

[bpossel]

Thanks Guys !  Very helpful !

One add'l relay (#29 working relay), what is it's function?  Not clear in the BBB?

[Peter van Es]

#29 is called "Arbeitsstromrelais". In my German BBB its function is not described, but translated litterally it means: working-current relay. From the diagram I included in my earlier post it appears to be wired up to:

• one terminal of the Relay box (#5)
• one terminal of the Stop solenoid (#6), which should keep power for 4-8 seconds after switching off the ignition, and which pulls back the controls of the injection pump to zero
• ground

I presume that the Relay box provides OUTPUT signals as INPUT to #29, and that it in turn provides an output to the Stop solenoid. I therefore presume it is some sort of delay relay, (keeping current for 4-8 seconds) to ensure that the function of the Stop solenoid is correct.

On the function of the two-way valve, Jeff C is correct. It is meant to engage either when oil temperature is under 17 degrees C, or when coulant is over 100 degrees C, or when the engine is over 2200-2400 rpm. The relays are just old fashioned logic circuits, providing the OR function to engage the vacuum valve. When the valve is engaged, the vacuum thingy should move the distributor timing from retard to advance ignition, at which point an RPM increase should be noticed.

Hey, but I'm not sure... this is an educated guess.

Peter

[jeffc280sl]

I think Peter has got it.  One question I have concerns the activation of relay #29.  I don't believe there is a 4-8 second timing circuit involved.  I think as long as the conditions, transmission sensor/switches provide a signal the two way valve will be activated.   In the manual transmission car the two way valve circuit/signal can be broken by pushing in the clutch pedal or pressing the gas pedal.  I think it is similar on the auto version.  BTW the manual transmission cars don't have the extra relay.  The relay function is included in the black box.

[Benz Dr.]

It just a bit more complicated than that but you guys have the basic stuff down pretty good. The vacuum signals are controlled by the two way switch over valve. On the late cars you have about 20 degrees of vacuum control and about 10 degrees of mechanical. On early cars it's pretty much the opposite with 10 degrees vacuum and 20 degrees mechanical.

You can't disconnect anything on the late system and expect it to work as intended but you can remove certain parts from the system. The 100C switch can be disconnected as well as the stop solenoid on the IP. In fact, it might be a good idea to disable the IP stop.
If you don't want to use the original system then you would need to replace the throttle body with an earlier type because the late throttle body provides a constant vacuum signal and is not influenced by throttle position. This would also mean that you would need to use the earlier 051 type distributor. The throttler body and distributors have to match ie. vacuum advance, vacuum retard and late CD ignition type.

If you want to keep the late system and the CD box still works then stick with that. Your main concerns should be a good vacuum signal and switch over at around 2200 RPM. The mechanical advance will be pretty much full at that speed and the vacuum switch over will make the transition almost seamless. 

[jeffc280sl]

I'll defer to Dan on the distributor mechanical and two way valve vacuum operation.  MSD makes a suitable rpm replacement switch for about $80 for those interested.

[wwheeler]

The 1968 USA model year doesn' have much as far as emission controls.  There is a Fuel Shutoff Value solenoid on the back of the Fuel Injection Pump (the lower of two solenoids).   This kicks in when the car is decelerating but often times is disconnected.   There's a Bosch Speed Sensor Unit and Relay on the left side of the engine compartment (behind the ignition coil) that often fails and sometimes would cause the engine to stall by activating the Fuel Shutoff Value at too low an RPM.  The Speed Sensor Unit is around $800 from the dealer -- I can only imagine one is purchased for a 100 point restoration. 

Concerning the '68 emissions, I was checking my fuel shut off system because I have lately been hearing some burbling in the exhaust when coasting. I was sure it was the infamous speed sensor( it wasn't). I used a test light on #30 pole on the "dual circut relay" to see when it received voltage from the speed sensor. Turns out, the speed sensor was working perfectly and gave voltage to the relay above 1150 rpm but not below.

Searching further, I think it may be the solenoid on the pump since the other switches are working fine. To test, I used a jumper wire to power to the solenoid terminal to see if it would click ( It didn't). So I tested my test method and tried the starting solenoid above it and it did click with the jumper wire attached. Before I purchase a new solenoid, does this sound like the right conclusion?

For people who have a bad speed sensor, I am checking on a company who might be able to rebuild them. I let you know if it works out.

[JPMOSE]

Wallace,

If you apply 12 volts to the solenoid directly (where the wire is connected), it should engage.  The speed control measures the speed via RPM.   Other conditions that must be met are closed idle switch (near venturi), microswitch and pressure switch on transmission.   Under these conditions, the Fuel Shutoff Solenoid should engage until the RPM drops to a certain point (measured by the speed sensor).   

Try applying 12 volts directly from the battery.  The Fuel Shutoff Solenoid self grounds via attachment to the injection pump.

By all means let me know if there's a source to rebuild the Speed Sensor!  Thanks.

[bpossel]

Hi Guys,

I had Beckman Technologies rebuild my speed relay and speed switch.

http://www.beckmanntechnologies.com/index.html

Bob 

[wwheeler]

Bob,

I called Beckmann about 6 months ago to see if they rebuilt that. I gave them the Bosch number and description and they said they could not and didn't have any info about it. Do you have any reference numbers that we could use so they would recognize what they did for you?

Thanks.

JPMOSE,

I also applied 12 volts directly to the solenoid as you mentioned and it did not engage. I guess it is new solenoid time! Thanks for your help.

[bpossel]

Hi Wallace,

Here is a copy of the invoice:

[wwheeler]

Thanks Bob,

The MB number for the speed sensor I was given from the Classic Center is different. The Bosch number is 0 332 010 001 and MB # I was given is 000 545 01 32. Is your Bosch number the same as mine? I guess the sensor may be different for a later '70 model vs. early '68 111 which I have. I will call them and find out if they know.

Thanks again for the info. I will still pursue the company I know and see what they can rebuild these.

[bpossel]

The number on mine is "000 545 24 32".  This looks like another good topic to start at some time?  Maybe many different numbers based on model, year, which components installed, etc....
Bob 

[JPMOSE]

The speed sensors on '68 and '69 are different than the later.

[wwheeler]

Concerning the fuel shut off solenoid, mine is definitely dead. According to several sources, they are NLA. The starting solenoid above it is available is not the same and has a different part number and cannot be used as a substitute.

Pacific Fuel Injection said it is usually just a broken wire that can be repaired and the dead solenoid is good to go. The hard part is messing with the crimp to get the case open. Hopefully he is right.

[JPMOSE]

Call Hans at H&R Fuel Injection in Long Island.....he may have a spare he could sell you (or rebuild yours).   Look this business up in our supplier list under the Technical Manual section of this site.

[wwheeler]

By all means let me know if there's a source to rebuild the Speed Sensor!  Thanks.

JPMOSE,
I have contacted a company that says they can rebuild the speed sensor. I sent them a electrical diagram of the speed sensor system and it's components. They said it should be no problem. The contact info is below.

They have rebuilt many temperature control boards for my company and are a good and knowledgeable company to deal with. I have discovered that my speed sensor actually does work so there is no point sending mine to them. I told the company that there are several MB owners who have a broken speed sensor. They replied that they would be happy to work with anybody who needs their sensor rebuilt. Please let me know if you get yours rebuilt as I would like to see how it turns out. Tell them that Wallace Wheeler sent you.

You can contact them:
Combotronics - Inola, OK
Atten: Tonya - 800-331-5941

[JPMOSE]

Thanks Wallace...it will be a while but I intend to do it.