Cold start with w124

[sub_zero]

Hi Guys,
I have a W124 E220 made in 1995,I noticed that when I start it in the morning,the engine does not rev up high and rpm gauge remains below 1000 rpm,and after few seconds it swtiches off ,I have to start it again,
after second try,the rpm gauge still below 1000 rpm ,but doesn not switch off!!!
I think in first cold start,the should engine rev up to 1500 rpm,then slows down as it warms up,so what is going on?
I have bought this car two years ago,it is always like that in winter,in summer it does not switches off,so what is the right behaviour?
Is there any thing I can do?
Thanks in advance

 

[grober]

fuel pump relay??

could be so many things. defective cold start valve,idle speed valve or temperature sensor. fuel pump relay or OVP relay connections ,partially blocked fuel filter etc. Symptoms all seem to indicate the car is not getting enough fuel/air when cold. I have found that if my car is very cold its a good idea to turn on the ignition wait a couple of seconds for the fuel system to pressurise (you should hear the fuel pump running) and then turn the engine over. the car should normal idle about 1200 rpm when cold and then as you describe slowly reduce revs to 750-800 rpm as it slowly warms up. the fuel pump relays are notorious for faults on this model so maybe the first thing to replace??? Others advocate cleaning the throttle body http://www.mbclub.co.uk/forums/showthread.php?t=20489&highlight=cold+start+problems
Sorry I cant be more specific

 

[sub_zero]

great list grober

hi ,
thanks grober,this is a good list to check,you remind me now that my fuel pump sounds very noisy,I think it needs more attention.
One more thing if you please,the thread you sent me is great(same as my engine),but I can't find the throttle body,is it that silver thing under the traverse black inlet manifold( black plastic ) end?how can I reach it?.Do I have to uninstall anyhting?
Thanks in advance

 

[grober]

throttle body.

yes the throttle body is the silver thing on the nearside under the black air cross pipe. SEE THE PICTURE IN RED.
A Crankcase ventilation hose attached to black air cross pipe (remove first)

B Circular metal clips loosen these.

C + D Thottle body+idle speed actuator (remove together)
you will also have to remove
1 a small vacuum line to the evaporative charcoal canister
2 the throttle return spring
3 throttle linkage
4 electrical connection/s eg wiring to the idle speed actuator.
5 unscrew the actuator mouting bolts and withdraw the throttle body.

TAKE CARE
disturb the engine wiring loom as little as possible ( can be brittle due to poor quality insulation)
carefully preserve the O RINGS or use new ones when replacing the unit.
dont knock the air mass meter at the other end of the air cross pipe when moving it.
EDIT:-LOOKING AT THE PICTURE YOU MAY ALSO HAVE TO REMOVE/LOOSEN THE ELECTRICAL WIRING TO THE AIR MASS METER!! RUNS IN A U-CHANNEL ALONG THE FRONTOF THE BLACK AIR CROSS PIPE. DIDNT REMEMBER THAT SORRY.

Thanks to PJH/Ian Walker for the original pictures

 

[sub_zero]

got you

Hi grober,
That was very descriptive,thanks,now I have successfully uninstalled it,do i clean it with fuel? or tenner? or are there any products avalibale in the market?
Wow,I may become an MB consultant here in Kuwait,they have no idea about these cars. :bannana:
thanks in advance

 

[grober]

carb cleaner

As a previous post suggests it might be caused by carbon build up in the throttle body by the butterfly valve.Using carb cleaning solution, remove the throttle body (done) and made sure all deposits were very carefully scraped away from the inside of the body around the butterfly valves closed position.
carb cleaner is usually a volatile hydrocarbon mix (Caution it make contain benzene and hexane which are harmfull by ingestion thro lungs or skin so wear gloves and avoid inhaling the vapour.) Motorcycle shops tend to to stock carb cleaner but I guess petrol would do at a pinch. Dont use agressive solvents like acetone which may degrade rubber or plastic parts!

 

[sub_zero]

Neat and clean but...

hi grober,
I did it,thanks very much,the engine now starts at 1200rpm when cold,but does not stay long at 1200rpm,soon it revs down,is that right? It wasn't like that anyway,I think this job was really needed for the car.
I noticed something,when you switch on the car and before starting,you hear something is opening inside the dash (maybe the immobilizer am not sure),I don't hear this sound any more after I cleaned the throttle,also I tried the AC and there is no air coming from the middle vents (I have climate control AC),only from the side vents ,also the head light leveling is not working,I think I opened the pneumatic circuit or something,I don't know ,but one thing for sure,something is wrong,Where I went wrong?
I checked all what I have uninstalled and they seem installed to me.
Any recommendations will be highly appreciated?
Regards

 

[grober]

vacuum system leak??

Doesnt take long for revs to drop so I guess your OK now for cold idling. From your other symptoms it does sound as if you have a vacuum system leak since I think there are vacuum operated valves in the heater/ air con system. I havent got air con on my car so cant help there. Check that you havent got a vacuum leak somewhere. Remember that if you move one end of a pipe it can come out of a union some distance away. the rubber unions can also perish or crack so better check the vacuum system carefully.

 

[sub_zero]

I'll check that...

Hi grober,
You said in your thread with a pic:"1 a small vacuum line to the evaporative charcoal canister", do you think this is the problem? It seems installed to me.
I'll check that again.
Thanks very much

 

[grober]

Vacuum Leak Test

that vacuum line 1 I mentioned goes to the evaporative charcoal canister which mops up fuel vapour from the petrol tank. Its located under the front wing behind the plastic wheel arch cover. This vacuum line cleans up the Charcoal trap when required. Its action is controlled by a valve via the Engine ECU. It should not effect the components you mentioned since they normally have another vacuum takeoff on the inlet manifold (I think) you will have to check all the vacuum takeoffs the inlet system and trace them to their actuator units. The engine is acting as a giant vacuum pump sucking in air to supply vacuum. FIRST thing I would do is to temporarily carefully block off the vacuum linetake off point you removed and see if this restores the other systems - (lights, aircon valves) then you know thats the problem. If not then you have to look for another source of vacuum leak. Thats if your evaporative system is the same as mine.

 

[sub_zero]

At last....

Hi grober,
I consulted a near by technician (I don't trust any technicians here,they learn the know-how on your car,pure beginners,but I said another eye may see things I don't see) and he saw another vacuum hose connected to the big silver thing attached to the throttle body (maybe the canister,i don't know as i don't know the canister ),anyway that hose was cut,I dont' know why,I replaced it and everything went well,my AC works fine(you are right,my AC has vacuum valves inside),when I switch on the car and before start,I hear the immobilizer opening,and I think the headlight leveling well work fine(it is day light now I cannot see very well). :bannana:
thank you very much grober,this is very kind of you.
case close.
Sub_zero
P.S. : I believe the W124 series are much more reliable than W210,W210 here in Kuwait has very bad reputation and prices are sinking fast!!!!!

 

[grober]

Sorted

Glad to be of help. Its what these forums are for. :bannana: :bannana: