Hey guys:

I've been living with the hard to start scenario on my 1983 190e. Basically what happens is that in the mornings when I crank it it will start fairly quickly, but then sometimes it hesitates for a few seconds before it gets a stable idle.

Then if I drive it around, go to the grocery store, come out and try to start it, I have to crank it for several seconds (no foot on gas pedal) and then eventually it "catches" and runs at like 100 rpm, brup brup brup, and after about 15 seconds it speeds up by itself to a stable idle at say 750 rpms. If I press the gas while starting, after several seconds it will start and race due to gas being pressed, but if I take my foot off the gas it slows right down and can stall. I have to nurse the gas paddle for the first few seconds until it stabalizes enough to keep running and then I'm set.

Either way once the car gets to the stable idle, then it runs and drives like there is nothing wrong.

What is up with this problem. Anyone figure it out? I've seen some posts about it in the past, tried to chase it a while back but I gave up. Now I'm trying to see if I can solve it again.

Incidentally, when it all worked some time ago (I've had this problem for over a year now), I used to click the key, crank for 2 seconds or so, and it was running right away at a stable idle. Something has changed and I don't know what, and, whatever it is, it doesn't seem to affect the way the motor runs once you drive away.

ANY help would be greatly appreciated. Thanks guys!

-=>Raja.

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1983 MB 190E, bought from Germany and shipped to the US in 1986.

RBORT,

Got your PM and read your description carefully. It sounds like the fuel pressure might be bleeding down after you shut the car down. When you shut off a CIS car, the fuel pressure should drop slightly to keep the inj ectors from popping on hot days and flooding the engine. The system should stay pressurized, however. If I'm understanding your description, you are getting better results on a cold engine, because you may be getting helped by the cold start valve. If you have the equipment, I would suggest running a pressure, volume, and leak down test on the fuel system. The next possibility is a problem in the aftermarket computer that was installed to make the car compliant with U.S. EPA specs. I am assuming you have a frequency valve that kooks like an injector valve plumbed into the fuel system. Unplug the electrical connector and see if it makes a difference. That should put the system in open loop and make it run like a basic CIS system.

I just had another thought. that system should have a warm up compensator on it. You control pressure may be way off the chart. That is another reason I suggest a complete fuel system test by the book. Checking the fuel pressure with the gauge and 2 way control valve allows you th check both primary and control pressure through the complete warm up cycle.

Good luck,
Peter

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Auto Zentral Ltd.

Hi Peter:

Thanks for the reply! Your diagnosis seems pluasible as the car does seem to be problematic when hot. I have two other points to mention:

If I stop the engine hot, wait 1 minute, and restart, it starts right away, but then the rpm drops to like 400-500 and then after a few seconds it recovers back to 750 normal rpm. Almost seems like a loss of pressure as you say.

If I stop the engine longer, when I go to restart the engine fires right away but dies right away also. Then you have to crank crank crank and after 5+ seconds of cranking the engine goes brup brup brup (if you apply no gas at all during starting), catches at something like 200 rpms, and shakes and hesitates for several seconds as the rpm SLOWLY rises to normal rpms. If I rev the engine for a few seconds this speeds up the process of getting to a stable idle at 750 or so.

I did remove the cold start valve and try to start the engine with it outside, but I never observed any gas coming out of it while trying to start. I was not sure it was working right. Then I bought a new cold start valve sensor and replaced it, as well as replaced the cold start valve with another from the junk yard. It does say on the sensor -5C 20 second delay, so then I thought maybe it only works if the temperature is below freezing and not for every day. So due to this, I don't really know if the cold start valve is working or not.

This morning when I started the car cold, about 1 second of cranking and it starts, hesitates for 2 seconds and is at a stable idle at 750. This is all with no gas pressed. Seems better than hot start, but not perfect nevertheless.

When the car used to be perfect, I used to crank for 1 to 2 seconds and it would catch and run smoothly right away. When the engine warmed, it would slow down the idle rpms a bit. Not that I say that I don't ever remember seeing it now slow down after warming the engine up, so something is wrong there from the start.

I don't have any specialized equipment and I don't believe I have an aftermarket computer. Looks like they just spliced the wire from the O2 sensor into one of the computer wires near the connector. I didn't untape it to see, but that is what I see by following the wire from the O2 sensor.

Where should I look for the conector? I looked at the throttle body and I have a connector in the back side. Is that the one? I would like get the system to run in "open loop" and see if the starting problem improves or gets worse.

Please let me know what I can do as the average mechanic without any special tools. Your advice is greatly appreciated!

On the lighter side of things, I flushed my radiator out this weekend (havent done it in several years!) and I installed a new thermostat in the housing. Now my car drives at a solid 87C down the road at normal operating temperature while it used to be around 80 or less in the past. One thing fixed!

-=>Raja.

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1983 MB 190E, bought from Germany and shipped to the US in 1986.