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1990 Mercedes Benz 190E 2.6
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Discussion Starter #1
Just when I thought that I had everything sorted out with the radio installed and the keyless entry working a new issue has developed. It has been quite cold the past few days in the -10 to -15C range. Not really COLD but it makes the car start funny. The symptoms are.
Turn the key to start and the engine fires immediately and I mean inmediately.
Then it immediately dies. This goes on for about 3 tries and finally the engine sputters to life and settles into a rather jerky idle just under 500RPM. If i touch the gas it sputters and may die but then in about 30 seconds or less it begins to respond to a bit of gas and revs nicely. After about another 15-30 seconds the idle settles without pressure on the gas pedal to about 1000rpm and begins to settle as the engine warms to normal and very smooth idle. The car runs and accelerates beautifully. Once warm it starts easily. This only happens when the ambient temperature is below about -10 and colder. I dont think it is the CSV since the engine starts at the turn of the key but I would say it seems to flood rather than run lean rather like the engine is trying to clear excess gas before it settles into a normal cold start RPM but that is only my uneducated guess. Any help as to where to begin will be gratefully received.
 

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Outstanding Contributor
'85 300D Turbo, '91 420SEL, '92 190E 2.6, '09 C350, '12 E63 Wagon
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Please remind me what weight oil you have in there again? That’s so cold relatively......
 

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1990 Mercedes Benz 190E 2.6
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344 Posts
Discussion Starter #3
5w30 recommended in the manual. It's going to get a lot colder?
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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I would say you may have to go back into determining if this is some sort of fuel issue or ignition. I would suspect fuel.
At those temps, your FD may start not working well for what ever reason.

I hate to say it Laura, but you may have to dust off (well it never got a chance to get dusty) your brand new toy, the fuel pressure gauge.
See if at cold temp (or at least when the car is not behaving in the beginning at -15c ambient) what is up with your fuel pressure.

At least you can eliminate pressure issues at this sort of temperature.

Sorry I have no experience with -15c starts, the car has never seen anything under probably -5c (maybe twice in 31 years), so very limited experience here.

I suspect at those temps the initial fuel enrichment is supposed to be very active, probably way over +20mA of EHA current, we may have to check into that too but that is a very linear effect, meaning since you have no issues above 0c the enrichment attempt/function by the ECU is just fine.
 

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1990 Mercedes Benz 190E 2.6
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Discussion Starter #5
Well I can hook up the fuel pressure gauges again. It seems that this only started with the cooler temps. It will go to at least -30 before long. I don't really want to be playing with the cold car engine then. It seems to sort itself out after a short times span long before the engine temperature rises. Could a temperature sensor be faulty?
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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We already know everything is fine with the fuel pressure at normal ambient temps (above 0c?).
We would like to check if the same is true with ambient temp <-15c.

So this experiment would need you to take the pressure readings when cold.

What I could suggest is to hook the gauge up after you use the car one day with the engine to keep you warm while you are working under the hood.

The the next morning just take/record the readings when it is <-15c.

I can not think of any other experiment at the moment.
 

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W124, 230E 5 speeds Manual, 1987
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@dolucasi couldn't be the Idle control valve? or OVP Relay bad contact or cold solder? my ICV used to stick when the weather is so cold and the idle will be jerky till I hear the ICV engaging later and this could be sometimes after about 1 minute.
I would try to tap on the OVP first when the idle is jerky and see if it changes things.
I could even suspect a sticking CSV(at a such very low temp ) as it will cause the same symptoms with fuel smell.
 

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'85 300D Turbo, '91 420SEL, '92 190E 2.6, '09 C350, '12 E63 Wagon
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@dolucasi -. That's COLD, man! Asking a lady to tinker with fuel pressure in -10 C - -15 C...

(Sorry, had to let it out)...

Hoping it has nothing to do with the remote starter...

Sent from my moto g(7) power using Tapatalk
 

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1990 Mercedes Benz 190E 2.6
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Discussion Starter #9
I have no problem working on the car in -15 or even -20 but maybe a bit reluctant at -30. I may just put the car away for the winter and buy myself a winter beater as we call them up here. I also suspect something sticking like the ICV or CVS running too long and cause a flooding situation? The fact that it idles at less than 500rpm without stalling is intereresting and then it wakes up and runs normal? I will do a fuel pressure test first as suggested. I might warm the top of the engine a light bulb and see what happens.
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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The reason why I ruled out a sticking ICV was because you said it also hesitates as you are accelerating, which does not involve the ICV so much as the air is being delivered thru the throttle plate.

It is rather difficult to diagnose this condition from far away, but if the ONLY problem was that the car is not holding idle and struggling, sure I would also say a sticking ICV could be a problem.

Checking that out is actually a much easier task Laura. So perhaps you should try that first as it would be a very targetted diagnostic.

I assume you own a hair dryer. So first thing in the morning warm up the ICV using it, and then start the car. If the problem goes away, you have your answer. If it does not you would have to move on to the next thing.
 

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1990 Mercedes Benz 190E 2.6
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Discussion Starter #11
Dolucasi, The car does not hesitate while accelerating once the car gets to a point that I can drive it. Typically the car starts and idles around 1100rpm but is drivable immediately. In this case it now takes 3 or 4 tries before it idles at about 500 or less and if I touch the gas it will die until it starts to idles faster and then when it settles into the 1000 rpm range when it acts normal. All of this takes less than a minute and before the engine makes any heat. My thought was to warm each component like the ICV and the temp sensor with a hair drier and see if this fixes the issue so I guess we are both on the same wavelength.
A bit warmer today at +8C so a chance to this problem occurs at warmer temps as well although it did begin when the thermometer dropped. Thanks and I will keep you informed.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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If i touch the gas it sputters and may die but then in about 30 seconds or less it begins to respond to a bit of gas and revs nicely.
Hi Laura, this statement in your original post led me to believe that in the state where it was having trouble idling, when you pressed the gas pedal (meaning when you give it more air) it sputters and may even die. So when you give it more air via the gas pedal it sputters. This is why I concluded this was not an air delivery problem but perhaps a fueling issue.

So the whole episode is under a minute? Maybe not worth chasing at this point but I would certainly try the IACV hairdryer experiment as it is simple and very directed.

Does the car behave exactly the same in neutral as well as park gear?
 

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1990 Mercedes Benz 190E 2.6
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Discussion Starter #13
I never thought to try that. I could live with it now but come winter and temps down in the -20 to even -40 range I suspect this will be a major problem. I have an electric battery blanket but no block heater and the car is garaged when not in use.
 

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1990 Mercedes Benz 190E 2.6
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Discussion Starter #14 (Edited)
Well I had a chance to play with the 190E this afternoon at a balmy +5C.
The car started with the same symptoms of multiple starts until it ran well.
The fuel pressures were 5.5 B line and 5.1B working.
The temp sensor (2 pin) is 685ohms @ +16C head temp.
The ICV shows 5.4 volts across the pins with engine running
8ohms across the pins and 1.7V with just the ignition on.
I checked it by momentarily bridging the pins with 12 , and it clicks.
I was going to check the fuse on the OVP relay but my hands arent strong enough to lift the battery to get at it so I will call the neighbour for help if you think this might be the problem.
I left the pressue gauge hooked up to the FD and will check it again in the morning when it will be a few degrees colder.
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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So your non ideal problem is back it seems, but a little worse with colder weather.

Everything there looks fine, you do not need to check the OVP. If it was failing you would not get any voltage at the ICV and BTW that is one way to check if your OVP is functioning.

Fuel pressure is fine too.

However:

The temp sensor (2 pin) is 685ohms @ +16C head temp.
Does not sound correct to me. Which temp sensor is this, intake air, coolant temp, aux fan switch sensor, other?

I believe the spec on all temp sensors is the same and my recollection is that it starts way over 1K over room temp., and goes down to about 330 ohms at 85c. Can you check the specs on that?
 

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1990 Mercedes Benz 190E 2.6
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Discussion Starter #16
The sensor that I checked is the two pin blue one. I think it is the one for the AC and fan. I would like to get the correct ohm or voltage values for the 4 pin one that connects to the CSV. I remember checking it once a while back but can't locate the numbers. If it is bad maybe the ECM is being fooled?
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Yes that one is just for the aux fan switch. Here is my measurement for that one:

90C - 290 ohms
85C - 250 ohms
70C - 800 ohms
60C - 1250 ohms
50C - 1670 ohms
40C - 2430 ohms

For the ECU sensor (4 pronged one) I can tell you that my garage is about 15c at the moment and it is reading 3500 ohms.

So their specs are very similar it seems.

Let's see your measurement for that one. Certainly the aux fan is off, or your measurement is not correct. You did unplug it right?

 

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Discussion Starter #18
Sorry no I didnt unplug bit because it wouldnt come free m didnt want to break anything and I measured from the two plugs which were attached to the sensor. I realize now that that was a mistake. I will take a reading from the 4 prong tomorrow with the temperature and see it it is within proper specs. If it is I don't know where to look next. Maybe an ignition issue but everything works well once the car gets over its hissy fit at start up.
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Yes, that will give you a false reading for sure. Also do not forget the intake air temp sensor. I believe yours has that (my '89 does not).

I would actually not look into ignition after these. I would measure the EHA current if you can. There you will see the fuel enrichment (if you have any) at cold.
At those temps is should be in the range of +20mA to +30mA for the first 30 seconds or so and will start coming down rapidly, linearly with coolant temp rising all the way down to near 0mA.

But let's take this one step at a time.
 

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Discussion Starter #20
Ok, I will need some guidance on how to measure the EHA voltage but I will get the 4 pin sensor checked first. Thanks you for your exceptional help.
 
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