Is there some thing that raises idle speed upon cold start up? I bought a 92 300D 2.5, a wouldn't start craigslist special. Fresh fuel & both fuel filters,and new glow plugs later it starts and runs smooth, WHEN warmed up . Problem is upon start up it dosn't want to idle smooth, when warming up, it will shake and stumble ,and will die.( Idle seems too low ) When warmed up , it idles fine, and is pretty quiet. Warm idles at 750 RPM, is that about right? What should I look at next? I have done the above, and will do oil & trans. fluid & filter change,and I will check brakes. At 229,xxx miles I have read to check timing chain stretch, that is on list. What else would a person do to a new car to check it out? I anxious to get it road ready. It runs down the road great, it's a rocket ship compared to our 83 240D ! Thanks for any help!

I have searched this forum with key words that apply to my problem, and didn't find anything helpfull. I did read a reference to a idle selinoid said to be located on rear of injection pump. I looked at mine , there is something in back and on the side with a vacuum line going to intake , but dosn't look electrical . If I make it stay running by keeping RPM's up until it gets warmed up , it will then run smooth . I just bought the car and it had sit for a while, previous owner said a month ,but fuel that was in it seemed bad or old. The car has ran at least a hour on new fuel and filters. I don't know where to look next. Can anyone help? Thanks, Charlie Klippel

I'm not 100% sure on that particular car, but there should be a 2-wire connector on the VERY BACK SIDE of the injection pump that controls idle speed. This is virtually the same engine as the OM602 as used in the '87 190D 2.5T's. From this connector on the back of the IP, trace the wires to find what I believe is called an ELR (don't know what it stands for). This will be a round knob that kind of looks like the adjustment knob on an air pressure regulator. Pull out on the knob, then rotate it to control idle speed. The knob is marked with a series of numbers, and there is an arrow to show which number the ELR is set on.

The ELR should be mounted on the firewall somewhere. On my cars (W201's), it is over near the battery.

Hope this helps.

SteveM

__________________
'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

Thank you very much, I will go look around for it now and try to do some adjusting. Charlie

I traced the wires back from the plug on selinoid located on back of the injection pump. The plug has two wires, a brown with blue stripe, and a red with blue stripe. They go into the wiring harness that runs over to behind the battery. I can't see where they come out of the wiring harness or what they go to. Behind the battery area there is two computers, and kickdown relay, also a curcuit breaker? I don't see anything with a knob to adjust any where.

Hopefully someone else will chime in with more details about the W124 cars.

I thought the ELR's were all mounted on the firewall - somewhere. Perhaps over near the brake booster?

SteveM

__________________
'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

I have been searching and reading forum posts for hours today trying to decide what to do next. I've read the EDS controls idle, and bumps it up at cold start. Warmed up it looks like RPM's is 600 and is smooth and quiet. At cold start up it trys to idle but bounces and shakes around, and will die. I would say RPM's bounce between 600 and 750. I have to keep my foot on the throtle a little to keep it running till warm. What should I do next? Get the codes read? Just replace the coolant sensor by thermostat? Maybe it is telling the computer a false signal? Would just resetting codes work? I've read a post on making a box to count flashes/read codes but, can I reset codes by shorting out a couple pins on that plug up by the battery? I am on vacation and trying to get this car going to drive next week. The car is SO much better than when I bought it, but I still need to get this this issue figured out. Thanks for any help. Charlie Klippel

The dreaded EDS (Electronic Diesel System)
[one of the computers behind the Battery] controls the Idle speed.
The classic test of the ELR
(That's the device on the very back side of the Injection Pump,with the wires you've already traced)
is to unplug the two wire connector(with the engine warm and running) and see if the idle changes.

I almost suspect that one or more of your New Glow Plugs isn't functioning...
'Rough idle at Start with a cold engine is one of the big diagnostic clues for
that Malady.Easy to test with a multimeter at the 5 aperture plug on the
Pre-Glow Relay (On the front side of the Driver's wheelhouse[Hump in the
engine compartment for the left front wheel] ) DG has posted a DIY on
Glow Plug Testing:http://dieselgiant.com/glowplugrepair.htm
[It's on an older OM617 series Diesel,BUT almost everything applies]
[Your Pre-Glow Relay is Electronic,it does not have the 80 Amp strip fuse!]

When you say new Glow Plugs...Only Beru or Bosch are worth installing!

What did your Primary fuel filter (Little in line plastic see through) look like?
'Any Black or Dark Brown Goo or specks in it?
If so your fuel system has the FUNGUS
('Grows in the Diesel/Water interface of your nice dark,cool fuel tank)
Which might be part of your problem...
This will fix the FUNGUS:http://mystarbrite.com/startron//content/view/94/124/lang,en/
It sounds like "Snake Oil" ,But it's not It works.
see video:http://mystarbrite.com/startron//content/view/82/112/lang,en/

Once you've sorted out this anomaly, GSXR has a "Website" devoted to all
things W124 :http://www.w124performance.com/images/

There is also a modification he spearheaded to eliminate a lot of the EGR
crap that disables Turbocharger Boost at:Wastegate actuator swap for OM602.962?
It's a long read but packed with information.

If you go to Mercedes EPC (ELectronic Parts Catalog) website and register
they'll give you a year of service for free[They want a US based credit card
number to prove you're a customer...no charge]:https://epc.startekinfo.com/epc/subscribe.jsp

This is the Mercedes Benz Club of Russia's Illustrated EPC site [Free]:
http://www.detali.ru/cat/oem_mb0.asp?TP=1
AND here's the 124.128 (It's a 250D in Europe) page:
http://www.detali.ru/cat/oem_mb1.asp?TP=1&F=124128_15S&M=602.962&GA=722.418&GM=717.437&
The RU site,as it's known,is more user friendly(AND usually updates Parts#s quicker)

I found this on another forum:http://www.benzworld.org/forums/w124-e-ce-d-td-class/1421010-online-w124-service-shop-manual.html
This is a link to a "Czech and Slovak Federative Republic"
(ČSFR, with the short forms Československo in Czech and Česko-Slovensko in Slovak)
website that has the actual MB service CD s for the W124 online.
CD1:http://mb.auto.pl/index.php/Dok.-serwisowa-CD1.html
CD2:http://mb.auto.pl/index.php/Dok.-serwisowa-CD2.html

More reading materiel:Bleeding Fuel Lines on 1993 300D W124
http://www.peachparts.com/shopforum/search.php?searchid=4168951

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__________________
'84 300SD sold
124.128

Compress Ingnite, thank you for the reply. you gave me a lot of info to look through. I have not looked through all of it yet. Let me answer some of your questions. I installed the BERU brand glow plugs part #GN858. I checked the OHM of them installed at the five pin plug as in the Diesel Giant guide. I have a cheap meter simular to his, same brand. At the same OHMs setting (200) , and subtracting the resistance from leads, all five would be at .5 OHMS. That should be good. I tested the five pins at the glow plug relay and through the wires .I am getting the 12 volts power to all places and to glow plugs. The light works right in the dash, and the car starts up good. The problem is at cold start, the idle not staying steady ,bouncing around too low (600 or lower),then up to where is should be at staying steady, (750). I am thinking 750 RPM's would be about right, this is from what I have read, I just got the car. I have a buddy with a 190D with the 2.5 , non turbo. He says his car will raise the RPM's on idle at cold start, then will lower when warmed up. On the fuel issue, I have drained the tank and put in fresh fuel in along with new filters. I have added some injection cleaner to the fuel. The car has ran at least a hour or two on new fuel and through new filters. This is at idle and drives down the road and back. It runs good warmed up. I poured a clear glass jar full of the fuel I drained out of the car. It had no black specs floating. Instead of just the green tint, it had a dark or grey tint also. I could not really see through it. It just looked old or not clean. I wouldn't think any or enough of the old fuel could be left to cause a problem. The primary filter shows nice clean fuel with just a tiny air buble in it. One other thing could be a clue, the exhaust on cold start up is a transparent grey color then a puff of black as the motor bounces back RPM's.It's not a blue smoke. It's not a thick grey smoke, like burning anti freeze. I did do a coolant system presure test. It held 15 pounds pressure for 15 minutes. That should rule out a head gasket problem, I would think. I am new to this car, but from what I've read and how my buddy's car act's, the car should raise the idle speed higher than it is on cold start up. If the EDS controls this, should I go in the computer codes direction? YUK! I have read the post on reading codes with analog meter. I don't have a analog meter, but I could get one. Again, thanks for your time and thoughts on my problem. Charlie Klippel

Charlie,

Try the simple test outlined below to take the ELR (Idle Control Actuator) OUT of the loop.
If unplugging the ELR device makes no difference ,chances are it's the "Boogieman".
[Unplugging a functioning ELR should cause a drop
in RPMs.]

"The dreaded EDS (Electronic Diesel System)
[one of the computers behind the Battery] controls the Idle speed."
Through the ELR actuator.


"The classic test of the ELR
(That's the device on the very back side of the Injection Pump,with the wires you've already traced)
is to unplug the two wire connector(with the engine warm and running) and see if the idle changes."

Second test ,With a Warm engine idling turn on the A/C ,Does the ELR
"Pick Up" the dropped RPMs caused by the A/C load? If not another nail
in the ELR 's coffin.

Other tests available on FSM (Factory Service Manual) [OR "CZ" FSM in this case]

If something is awry with the EDS computer[Unusual],I do not think there's any "Fixing" them.'Just replace...(ReCycler's)

Perusing the FSM for a few , Back soon

__________________
'84 300SD sold
124.128

I forgot to mention the ELR unplug test. I did unplug the ELR plug while running at just under 80c temp. The RPM's dropped from 600 to 500. It stayed running, and still smooth idle. Not as smooth as 600 RPM idle, because so low I guess. I also started the car cold with ELR unplugged, amazingly it idled smooth at about 400 RPM's, untill it died. It ran for a minute or two, before it died, this with my foot not on throtle . It seems the ELR system IS raising the idle. But is it raising it enough. Or is this a engine condion issue? One other thing I might add on that note. On cold start, I have to hold down on the throtle a little to keep it running. I do get exhaust smoke with some blue in it. It's hard to keep it at a spot idled up without the turbo taking up the RPM's. That blue smoke is not too unexpected on cold starting a engine with 229,xxx miles ? Thanks again, Charlie

Be not concerned with a puff or two at start.

The drop in RPMs from 600 to 500 Kinda guarantees the functionality of both
the EDS and the ELR in Idle control.

I don't know if raising the Mechanical Idle setting also allows the ELR to do it's
job easier (Consequent raising of the ELR's starting point for Idle Control) ,BUT
I think you're about to find out...

In the three Pictograms You'll notice your idle ,with the ELR unplugged, should be a minimum of 580 RPMs (620 +/- 40).
So your Idle (ELR OffLine) is somewhere between 80 and 160 RPMs too low.

This is the complete page of the CZ FSM:http://mb.auto.pl/wis/w124/CD01/Engine/602_603/07.1-2053.pdf

That "LockNut" 3a is right Above and Forward of the ELR (Y22),I don't know how much fun it is to get to with the Intake Manifold installed...
Out to look under hood...
(O.K. I'm Cheating the OM602 I'm looking at has the Cruise
Control Actuator removed from the Driver's side of the Intake) The LockNut
3a is a 13mm. The Idle Control shaft itself is a 6mm Hex (I think). I cannot
get the 6mm socket on the hex shaft ,because the ELR's pins are in the way.
So you'll need a 6mm box or combo wrench for it.

Just another thought...How certain are we that the Injection Pump Timing
is correct ? I'll bet Incorrect Timing affects idle...BUT if you ReTime the IP
at a later date the Mechanical Idle setting is easy to adjust.

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__________________
'84 300SD sold
124.128

On this line drawing , what am I looking at , where is this linkage and adjusting nut. Is this on the injection pump and the two prongs sticking up, is that where ELR plug goes ? I don't know what I'm looking at in the drawing ! I can only hope it could it be as easy as raising the mechanical idle speed. !

OK now I see , I must have got excited and not absorbed the whole post. I will go out and look again. Thanks so much,Charlie

Yeah,well the "Line Drawing" as you call it
Shows a "Handle" on the Mechanical Idle Speed control Shaft (6mm) ,BUT mine
is just a "Naked" 6mm hex shaft.Maybe yours still has the "Handle" ?

Remember, Check your cables and "Doggie Bones" in the control system for ease of motion (proper movement range and freedom),before
adjusting the Idle Speed.

1.Also the engine should be Warm 80 "C" (That's about a twenty minute run)
2.With the ELR unplugged to adjust the Mechanical Idle properly.

__________________
'84 300SD sold
124.128