Hi,

My 1985 mercedes 190e has this idle problem now and has for some time.

It idles rough on start and it actually stalls unless i give it gas until the engine has warmed up which takes about 2-3 miles to achieve. Then it runs fine(so while its still cold ....when coming to stops or lights.. i have to put it in neutral and give it gas to keep it going or give gas/hold break peddle to keep it going)

now i changed the mass airflow system, put in a new hex key and adjusted the air fuel mixture, the spark plugs, cap and rotor are fine, I changed the overprotection relay and fuse in it.

the cold start valve was changed about 3 years ago.. maybe that is the problem? or the idle control valve? my mechanic and I can't figure out WHY it stalls upon start and idles rough when engine is cold.

any help would be much much appreciated .
Thank you
Adam

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It sounds to me like a cold start system problem. My Volvo 740 turbo had the same symptoms. Get a helper start the car while you connect a VOM meter. Check for a signal to the cold start valve by removing the retainer clip (an exacto knife is good to pry one end of the clip away) and carefully connecting the multi-testers leads onto the plugs contacts. Dont jam the leads in, you will spread those contacts apart ruining them. Just a light touch onto their front surface is all thats necessary. If your coolant temperature sensor is working and the engine management module is working properly, you will get a signal to the plug and valve solenoid. If there isnt any signal from an ice cold dead start up cycle, test the coolant temp sensor with your meter set on Ohms and detect a change in the resisitance as the car warms up. If there is a signal at the CSV, remove the valve with the electrical connector on, and during a cold start, see if you get a spray from the valve. If you do get an ample spray, your rough cold start problem lies elsewhere....(maybe a weak ignition coil) If there is no spray, and a signal is present from its plug, the coil in the CSV body is open, or the fuel delivery line to the CSV is blocked (unlikely). An open coil in the CSV will show as no change on the display of the VOM when set on Ohms.
Dave....
Sometimes just cleaning the plug ends of the temp sensor or CSV will fix you up!

Check the wire go to EHA at fuel disb. Some time the wire broken . check for air leak. turn up the idle. On 85 190 adj at helf way down 3&4 intake runner. Push down the afm .Use carb cleaner clean the throt bore. Re set idle co to 3.3v. Use volt meter check at pin #3 at x11 diagnostil socket. Hope this help.

Nice looking car but I would change that grill with the big star.

Not necessarily a cold start problem. If it starts Ok from cold, that suggests the CSV is functioning as it should. I'd start looking at what the engine management system is doing while the engine is warming up. If it was the ICV, it would stall regardless of engine temperature. If it runs ok when warm, I would start looking at what's going on in the warm-up cycle.

Measure the current at the EHA when you start the engine from cold. You'll need to rig up a harness but you basically need to pull the plug, rig a short lead to reconnect one of the pins and hook a current reading multimeter between the second pin male and female contacts. At startup, you should see + or - 20 mA registering on the meter which shows it's running rich for a cold engine, this should drop down in stages to +/- 0 mA as the engine warms to operating temperature. You can do this in the garage under the bonnet, or you can get plenty of cable and run the leads into the car so you can keep an eye on the meter as you drive around. If it's a digital multimeter, you'll see if it's a + or - signal. If analog, you'll need to switch the polarity at the meter until you register a postive flow.

Do a search on measuring EHA current to get the correct figures for your engine - there's plenty of posts on this subject - but I'm betting your engine thinks its already warm and sets the mixture accordingly. I seem to recall there's a special case for your model in that the current is always positive, whereas the later models had a +/- variance but the basic principle is the same.

You could also check the resistance of your temp sensor. Don't know what the figures would be for your engine but you should be able to find it with a search, if nothing else you should see a change in resistance as the engine temperature rises. I think that's your culprit.

good luck with it.

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1987 300e manual 250,000 km (sold)

I have the same problem as everyone else, My 1989 109E 2.6 engin# 103.942, chassis# 201.029 with CIS stall like the key was shut off when it is over 85 deg. C. but starts rite back up. Also it idles low, 500rpms as soon as it reaches 85deg all the time. these two problems may or may not be related, I don't know. I see you all talking about this but no complete conclusions. I believe it's a heat soke issue, but what part? It has to be electrical, I've checked fuel flow and pressure.
I changed the 4wire temp sensor and the OVP relay.
First question: what tells the engine computer how fast the engine is spinning? The crank sensor?, the mas airflow?, the manifold absoulute pressure sensor?, just the RPM sensor or all in conjunction. What would heat up the most?
Something is telling the computer the engine is spinning faster than it really is and is closing the idle air control motor, I cleaned the IAC with Brake Cleaner, wasn't really dirty. I tried to raise the base idle with the throttle plate adjustment screw under the MAS and the computer put it back to 500rpm, only the TPS advanced base timming, so I put base idle back. When engine cools back to 85 deg. C the stalling stops and idle goes back to 650rpm. I pulled out the timing resistor and this did give me 25 more rpm and more hp.
This only happens when its hot, so my next step is to heat up each part with a heat gun until it stalls.
It's all guess work for me, anyone got any ideas?

I think you're looking in all the wrong places and I'm not even sure you have all those sensors and things on a 103 motor. If you've already changed the OVP relay, my money is on a dodgy solder in the ICU or a flaky wire.

First thing you should do is check to see if you have power going to the ICV when the engine is idling at 500 rpm. If no power, you need to trace it back to the OVP and from there to the ICU to find the short. What worked for me was giving the ICU a good whack which would restore power and idle control.

Another thing I can recommend is the purple wire grounding idle mod. You'll need to search for more info on this but its good for raising the idle another 50rpm which will help a lot with stalling issues if you have got something dodgy in the idle control. I'll see if I can find my notes or the links but IIRC the procedure is different between the 190 and 300E so you'll need to do some research yourself. It does work, though. I can vouch for that.

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1987 300e manual 250,000 km (sold)

'87 300E Stalling

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1987 300e manual 250,000 km (sold)

Simmo,
In reply I just added that I tried raising base idle and the computer put idle back to 500rpms, so I know that the computer is in control and is responding. Could the RPM sensor on the rear of the motor be getting a false reading or sending a false signal? With heat, resistance increases. Does this sensor generate its own voltage, like a piezo cristle Like in the knock sensor or is it a hallaffect switch? I am new to MBZ, but know OBD2 verrrry well.
I love this little car but the stalling is a safety issue.

Spang

My 1985 380SE does this too, but mostly in the summer. It will sometimes stall when hot, when coming to a stop, making a low speed turn, or when shifting into gear from a stop. When the engine is cool, or cool outside- it never stalls. However, on the flip side, when it is cold/cool outside- it will have a rough idle (especially when I start it in the morning)- almost missing and will sometimes continue throughout my trip, but only occasionally. I have not checked for air leaks yet. Idle control valve was checked and good though. Funny- when I start it in the mornings and do not press the accelerator- its fine, but when I rev the engine a bit, it starts missing and spluttering. Its been doing this for a year, but I would like to fix it, as it is annoying.

??

Don't overcomplicate the issue. I know of no way of raising the base idle other than the method I have outlined above, which was based on a Service Bulletin covering the late 80s models. I think you're looking for stuff that isn't even there on your engine.

Did you check voltage to the ICV? If the engine is idling at 500 I doubt it is working, idle should be at 700.

If this is only happening when the engine is hot, check the ICV connecting hoses for leaks, although I think this is more likely to result in a hunting idle rather than stalling.


86560SEL: There should be no need to touch the accelerator when starting the car, it's designed that way. As for the stalling when hot, I'd suspect the hoses on the iCV for wear and cracking from the symptoms you describe but I don't know anything about your engine, is it an 8?

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1987 300e manual 250,000 km (sold)

Thanks. I think you may have misunderstood me. lol. I do not press it before I start it. I meant after I start it, I would sometime depress the pedal (aka racing the engine slightly) to hopefully think it would smooth out sooner. Yeah, I have two carburated cars that require "pumping" the pedal, but you are right- my MB is not one of them.

Yeah, my car has a 3.8L V8. Thanks!

Simmo,
The way I tried to raise "base" idle was to turn the screw that sets the position of the throttle plate under the MAS, it does raise the idle for a moment, then the computer compensates. I read that forum about raising the idle my grounding the wire but i don't know what wire, I need a wiring diagram for the 190e. When I get one I will try it.
One of the local MBZ tecs here in San Jose said it mite be the EHA, What does the EHA do? How can I check it? Also I did not check the ICV voltage because the computer does control the idle, IE: AC turnes on, the computer compensates and raises the idle back up to 500 ect.
I realy need a repair manuel for this car, but cannot find one. Smyth European wants 75 dollars for a CD verson , more than i want to pay for a one time thing.
I got a MBZ because I was under the impression they were reliable, after reading these forums I am starting to question that, I see alot of people talking about idle problems, but I only have a problem when it's over 85 deg C, and here in California it's always hot outside. Today it was 75....in November! First time for me, I'm from Seattle.

OK, now we are getting somewhere. Although this is not necessarily a good thing in your case. There's no 'base idle' adjustment in the fuel system and engine I thought we were talking about. Neither is there a screw setting the position of the throttle plate, not even a MAS.

Best thing you can do is start a new thread instead of necroing this old one, post the engine numbers so we know what version we're talking about and do some research.

There's more than enough info available in this forum to fix anything, and everything, that goes wrong with a Benz. Once you've done that, you can start thinking about reliability. The worst thing you can do, ever, is to buy a 17-year-old benz with no service history and expect it to run like a new car. Took me three years to fix all that was wrong with my 300E and now I wouldn't swap it for anything.

good luck

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1987 300e manual 250,000 km (sold)

http://youtu.be/3CjFhewHrOsI am working on 1985 Mercedes 190E 2.3 gasoline engine i replaced the engine after finding the cam lobs worn, however this replacement engine is running rough. the timing i am not able to check as it says somewhere that the 5 degrees before top. i used the dash board economy gauge to adjust the air fuel mixture, as i turned in clock wise till it almost quit running then backed it off till the needle read the highest vacuum. the rpm at this point increased to 900 from 700. if it is supposed to idle at 500, i am in trouble. t has new plugs and all cylinders are firing. I believe my ICV is working and i checked for vacuum leaks. the temperature is just above the 48 on the dash indicator. the engine smooths out as the rpm increases and when i put it in gear reverse or drive the RPM drops.