bram_r - 7/1/2008 10:05 AM

Indiana Drew - 7/1/2008 4:29 PM

fernweh - 7/1/2008 1:40 AM

DesertStar - 6/30/2008 2:15 PM

I am still a little bit confused that maybe I have things hooked up wrong. Looking at the EPC, diagram shows electrovalve for a/c idle going to distributor and throttle plate. How would this increase idle when activated ?

Mike

IMO the vacuum line comes from the intake manifold goes to the electric solenoid and then to the ignition distributor. When you advance the ignition timing the idle rpm will increase. You can figure out if the vacuum pot on your distributor advances or retards the timing - if at normal running condition the timing is retarded the solenoid drops the vacuum (vents the line), ignition advances a bit and the idle rpm goes up a few - one of two scenarios Karl

All this makes sense - should the air inlet on the module be filtered i.e. draw air from post filter intake air or does it not matter?

All air and vacuum connections as discussed and pictured are behind the air filter and thus filtered. Just connect everything as MB intented and you'll be fine. Bram

I get it now! I was having a blond moment ... Thanks!

The existing vacuum connection flows as follows below - does it seem correct?

(Vac A.jpg)

Vac A.jpg (69KB - 10 downloads)

I have come to the conclusion that is correct and that is how I will be hooking mine up.  I looked up other M110 chassis models and all had pretty much the same page, other than those with a smog pump and gas tank vapor recovery...as it seems those had a vacuum pot on the distributor with two ports.

I will have mine complete by tomorrow night and will take photos along the way.

Mike

Mike

Have you looked at the flow through your electrovalve? I will be giving it another look tomorrow, but I did a trial test today and I didn't have the desired result. When I hooked up the valve as in the diagram, my idle still dropped when I turned on the AC ... I still don't understand the mechanics well enough to get the "big picture." Tomorrow is another day to learn ... Hope yours works better than mine ...

Further research shows numerous changes and differences in relation to idle control for the various MB chassis. Here is a diagram from a W107. This is what I tried to emulate to begin with, but I think this is not right for MY wagen....but may be for an earlier one.

If anyone else is following this thread...does any one know how the bypass valve #14 works ? Or any vacuum check valve for that matter?

 I am still going with that diagram I posted from the EPC for my vin, very much simpler, and if not right maybe I could do both with two switchover valves.

Mike

(w107 acconnection.JPG)

w107 acconnection.JPG (113KB - 12 downloads)

"Or any vacuum check valve for that matter?"

I have a little check valve in line as pictured below - it only lets the vacuum flow in the direction indicated ... From blowing through it, I can only guess it works like any other check valve, i.e. diaphragm that only allows the flow in one direction ... I'm not sure if what you are asking about is the same piece about which I am answering, but I can snap some pix of the actual system if you want to see exactly what mine looks like ...

If the electrovalve is hook up as shown, then the flow is as follows:

Without current from the Air Conditioning (valve in normal position?) the flow is red arrows to green arrow and with the Air on, red to blue path ... 

(Vac B.jpg)

Vac B.jpg (120KB - 10 downloads)

Thanks for the explanation.  Now for your question, I am sure the answer is here somewhere:
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/Index/110index.html

Mike 

Mike:

Hope you made better progress - This is what I found today:

Hooking the White/Red Vac line into the module as shown in the diagram you posted yielded no change in the RPM in any combination.

Removal of the White/Yellow Vac line yielded increase in the RPM, but still didn't figure out how the module should be hooked into that line to accomplish the increase in RPM as desired  ...

This is how the distributer/VAC setup looks on mine ...

(Vac C.jpg)

Vac C.jpg (208KB - 8 downloads)

Something does not look right on your layout.  Do you have a check valve hooked up here ?  Here is a photo of what I did today...will test out tomorrow.  If does not provide desired results, i will go back to my original layout...it worked.

Mike 

(indianaspaghetti2007.jpg)

(crappyschematic [800x600].jpg)

(crapierschematic [800x600].jpg)

indianaspaghetti2007.jpg (89KB - 7 downloads)

crappyschematic [800x600].jpg (135KB - 6 downloads)

crapierschematic [800x600].jpg (121KB - 5 downloads)

Mike

I thought as you do, the valve should be in the white/red line and yes, the black/red/white is a check valve. I will take some clearer shots of the distributor in relation to the intake. The white/yellow line goes to the lower portion of the intake. The white/red with check valve goes into the upper portion. Anyway, pix will give a clearer view when I get them ... Getting closer!

So from the intake, where does your white/yellow line stop at/connected to ?  Your check valve is there for something.  PM or email me your vin...let me see if I can see something to give me some clues on your system.

Holy cow, it is late, I better get to bed. 

Mike 

Mike,

I tried to read the thread, but I got lost.  What makes you think the switchover valve between the throttle body and the distributor has anything to do with AC?  It looks to me to be more likely to be involved with EGR.  Fiddling with ignition timing is not the normal way to adjust idle speed, as you see from your 117 diagram, a simple air bypass is what's in order.  Timing adjustments ARE absolutely used with EGR because EGR leans the mixture and requires retarding of the timing to prevent knocking.  My guess for the valve between the throttle body and the dizzy is that it probably retards timing under off-idle conditions at specific engine temps (either hot or cold).

Have you verified under what conditions the solenoid is active? (tee a vacuum gauge into the line from valve to dizzy)

Bram was on the right track when he was talking about the "#14" and "#43" If you look at your post way up top that starts with  "I can't tell you what color it is"  You'll see that in your system you have the following air bypasses:

1- the white screw

2- the cold idle air bypass

3- the schuber-thingy

4- this piece of gray/white looking tubing that you put a red circle on

That last one should have a valve in it....The #14 valve from your W117 diagram.  I thought that was what you were trying to do with the vacuum "X" fitting, but I couldn't figure out how that would accomplish the need (didn't see answer to my question about it).  All you need there is a simple on/off valve placed in that line with the correct orifice in it to allow the right amount of air to increase idle speed a touch.

That said, I would be moreinclined to think of the AC air bypass as wanting something larger than the little white line you have circled in red.  My guess is that #14 should be plumbed between the two openings that you plugged - the ones used by the federalizer for vapor recovery?

Just my thoughts.

Good luck!

-Dave G.

PS - Indiana, the reason the idle increases when you pull the yellow line is that you've created a vacuum leak into the lower manifold.  What you've also done by venting that line is eliminate any possibility of vacuum advance for your ignition.  The yellow line isn't the place to look for AC idle increase.

Hi Dave, you probably got a little lost because frankly I am too, and have been throwing darts on this thread.   My first initial idea for idle speed adjustment was what you described, I honestly thought I made connections right, but later questioned (when Drew questioned me on his hookup) as I had the changeover valve just spliced into that line from the hose to the ventil (circulating air booster valve).  Never really had any a/c idle issues however. 

I than looked up the EPC and saw that diagram of lines going to the distributor and intake from the changeover valve...I immediately assumed something was wrong with my setup (splicing line as noted above) and questioned whether the distributor connection was right.

There have been a lot of fingers in my system from previous mechanics, who (I believe) really did not have an understanding of the system and who may have changed air hoses from sedan models for ease and cost while doing previous motor work before I took possession. I am trying to piece together what MB intended and have reached a stumbling block (and big mental block as well).

I believe at one time something existed as you illustrated with a separate bigger line resembling those going to the circulating booster valve as in the photo attached....but there was never any connection on the opposite hose to make a bypass.

The valve on the distributor was lined into the throttle body.  I do not think that is right, do you?  

I did pull up schematics on the EGR, but nothing shows any connection to distributor.  EGR line goes throttle body to thermo valve on the exhaust side port, than from there to EGR valve.  So, with EGR hooked up, I would be left with two open vacuum ports...that on the distributor and one left on the throttle body.  I assumed the a/c idle changeover valve did.

I will need to test vac valve on dizzy as you suggest, but still questioning what it "should" connect to.  I have attached image of EGR piping and my old air hose with additional ports.  The other image shows my new hoses.  I probably should have researched more and sought hoses with orifices to connect as I have shown.

Thanks for you thoughts Dave.

MIke 

(hoser1aa [800x600].jpg)

(egrpiping [800x600].JPG)

hoser1aa [800x600].jpg (117KB - 6 downloads)

egrpiping [800x600].JPG (48KB - 7 downloads)

Mike and Mike D

I think I will be laying back on my system as I don't have some of the "innovation" from the later years. The drawing that shows the electrovalve in line with the vacuum line from the distributor to the intake does not seem to do anything to boost my RPMs with the AC on ... by raising the RPM to about 850 - 900 I have about 550 with the AC on and thats enough to keep me from stalling at traffic lights. I will keep following along to see is anything you discover in the future applies to Erlla ... Doubt I can be of assistance, but let me know if I can ...

I put the subject line I did on this one becuase I'm pretty sure that Dutch's 460 came from the factory with AC.  If he'd be willing to share his VIN with you off-line, you should be able to find the right parts by plugging that VIN into the EPC. 

I believe the switchover valve in the line between the throttle body and the distributor was very functional and correct when you had a working EGR.  It did not conect in the EGR circuit, it most likely served to change ignition timing under some conditions likely related to when EGR was functioning.  Now that your EGR is plugged, that circuit very likely serves no purpose.

The manuals I have here also don't show any vacuum information, and are for earlier, simpler models anyhow.  I even checked my Bosch injection manuals but they stop with the idle air bypass valve and don't go into any of the minutia of the fine trimming vacuum circuits.  I could stop by Mark's place on Monday and raid his stash of manuals to see if I can get anything else to add for you.  I found the info on the functionality of the "schuber-dealy" there for Bram, so maybe I could dig out something on EGR and AC vacuum circuitry for you.

-Dave G.