My '92 190 2.3 started this phenomenon all of a sudden. It did however happen once before and it resolved it'self without any human intervntion at all except we came back 5 hours later. This is the dilema. I drive home Friday. (not suspecting any problems) don't drive it Saturday, then go out to get to church and it turns and turns and turns and turns. Every once in a while there would be a very weak backfire when dissengaging the starter, but no more. Gas flow was confirmed up to the injection system, and there is spark. The spark, however was suspiciously "red". Also, using the very safe and effective method of putting a small bit of gas into the air intake produced no results at all. Now it has been a week and no change at all.

It was our thought that the spark, although present outside of the cylinder, was too weak to ignite the fuel air mix. Could this be posible? Has anyone had this problem or aything like it? Please Help.

Thanks
Justin

Sounds like ignition coil failure. Seen this many times

Yes, you can get spark outside of the cylinder, but not inside. Typical bad coil. I now keep a spare used coil to sub in if I suspect that is the problem.
Chased that problem for awhile once on a 560 V8.

I just replaced the coil and there is no change in the condition except that the spark is stronger. Any suggestions? This might be the end of my technical abilities

Good chance the eng is flooded and the spark plugs fowled, pull the spark plugs and inspect, if they look black and sooty replace them.

Now you need to de-flood the eng, best way is to remove the fuel pump relay and then crank with your foot hard on the gas pedal, this opens the throttle plate wide open allowing maximum air flow. Probably have to crank for a good 10-15 seconds, eng may fire briefly.

Or if you don't know where the fuel pump relay is, you can still hold your foot flat and crank it over, but it will probably take a bit longer and remember to take your foot off the pedal once it fires.

good luck
ozzy

It was our thought that the spark, although present outside of the cylinder, was too weak to ignite the fuel air mix. Could this be posible? Has anyone had this problem or aything like it? Please Help.

Thanks
Justin[/QUOTE]

Yes. This happened to a friend's 560SEL a few months ago. It obviously had fuel (strong fuel smell at the exhaust during cranking), and pulling a wire and connecting it to an external grounded spark plug showed what appeared to be a good spark. Bottom line was that the coil was weak and a new coil put him back in business.

The other thing to check is the OVP relay. It provides power to the "E" portion of the KE system, and all the cold start features are in the electronics, so a bad OVP relay can often mean no cold start or very hard cold starting.

Duke

check the breather hose underneath the intake. it may have popped off as they do.
paul

__________________
Paul Roberts
Mercedes Centrum Inc.
Bellevue,WA.

You may need to look at ignition timing -- these engines are crank triggered and have the electronics located just above the coil (module with a vacuum line going to it). The distributor is used only to dirstribute the secondary HV to the plugs ... if this is in the wrong position, you will have a poor and incorrect spark (the bolt for the dist. may be loose) -- pull the coil wire off the distributor and check the spark there.

Also ... if you have been cranking your engine for a while with fuel... the fuel will wash down the cylinder walls and into the oil .... when you get the car running again ... change the oil right away.

Stefan.

Did the spark look any different after changing the coil? It should be a fat, blue spark. If it is, then pull the plugs, at least one or two and see if they are gas fouled as zracer pointed out.

Good luck,