Poor starting and cold running.
Thread Starter
Junior Member
Joined: Jan 2006
Posts: 57
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From: Manchester, England
1993 Mercedes 190E
Poor starting and cold running.
This is a 1993 Merc 190E with electronic ignition and fuel injection - so the problem isn't faulty ignition points or a blocked carburettor jet.
About 3 or 4 weeks ago it decided to get difficult to start if it had not been used for more than a day. Not so much a 'cold starting' problem, more like it was getting lazy from lack of exercise. Anyway, during the week it was getting used every day - to and from work - and was faultless as usual.
At weekend I would be driving another car till come Sunday afternoon and the Merc would be very difficult to start. Spins on the starter fine (good battery and starter motor) and when tested the spark is fat and strong, but it just doesn't seem to like the idea of firing up. It will fire occasionally but not 'catch' and run right without a lot a cajoling. Once it has at last started, then it is really difficult to move off aswhenever any attempt is made to get power off the engine - like rolling slowly forward - it mis-fires and dies unless you are VERY carefull.
After a couple of miles of trying to drive like this, if it will make it onto a motorway, a few miles at a decent speed and it is purring away like a *****cat. Perfect untill next weekend.
Over the Christmas break, the Mercedes wasn't used for about a week. The result is that now it will just merrily spin on the starter and hardly fire - certainly not enough to actually run.
My initial thoughts were to a blocked fuel filter or something like that, but if it were so then a few miles bash down the motorway wouldn't sort it out for a week would it ?
I am now wondering if there is some sort of fault with the fuel injection system or maybe the air intake - like an air-flap stuck or whatever. Hopefully it will not be something massively costly, like the ECU (engine control unit, otherwise known as 'engine management computer').
Last weekend, I checked over the ignition system and gave everything a good waterproofing just in case I had been thinking along the wrong lines, but still no joy. With a freshly-charged battery, I was able to keep it spinning on the starter for quite a while and noticed that if I held the throttle down about half way and pumped it rapidly up and down the engine would fire while the starter was engaged - but it stopped as soon as the starter was released.
I think that the fact that, once it is running, it will work perfectly untill it is left standing for a couple of days must be the major clue here - but what could the problem be ?
About 3 or 4 weeks ago it decided to get difficult to start if it had not been used for more than a day. Not so much a 'cold starting' problem, more like it was getting lazy from lack of exercise. Anyway, during the week it was getting used every day - to and from work - and was faultless as usual.
At weekend I would be driving another car till come Sunday afternoon and the Merc would be very difficult to start. Spins on the starter fine (good battery and starter motor) and when tested the spark is fat and strong, but it just doesn't seem to like the idea of firing up. It will fire occasionally but not 'catch' and run right without a lot a cajoling. Once it has at last started, then it is really difficult to move off aswhenever any attempt is made to get power off the engine - like rolling slowly forward - it mis-fires and dies unless you are VERY carefull.
After a couple of miles of trying to drive like this, if it will make it onto a motorway, a few miles at a decent speed and it is purring away like a *****cat. Perfect untill next weekend.
Over the Christmas break, the Mercedes wasn't used for about a week. The result is that now it will just merrily spin on the starter and hardly fire - certainly not enough to actually run.
My initial thoughts were to a blocked fuel filter or something like that, but if it were so then a few miles bash down the motorway wouldn't sort it out for a week would it ?
I am now wondering if there is some sort of fault with the fuel injection system or maybe the air intake - like an air-flap stuck or whatever. Hopefully it will not be something massively costly, like the ECU (engine control unit, otherwise known as 'engine management computer').
Last weekend, I checked over the ignition system and gave everything a good waterproofing just in case I had been thinking along the wrong lines, but still no joy. With a freshly-charged battery, I was able to keep it spinning on the starter for quite a while and noticed that if I held the throttle down about half way and pumped it rapidly up and down the engine would fire while the starter was engaged - but it stopped as soon as the starter was released.
I think that the fact that, once it is running, it will work perfectly untill it is left standing for a couple of days must be the major clue here - but what could the problem be ?
Last edited by kepla; Jan 13, 2006 at 09:08 AM.
Thread Starter
Junior Member
Joined: Jan 2006
Posts: 57
Likes: 0
From: Manchester, England
1993 Mercedes 190E
Time for an update:
I spent a bit of time with the errant 190E today. Took off the air cleaner and generally checked around the intake and stuff like that. Everything looked okay - clean and moving freely - so I tried starting it again. No joy after about a minute's cranking on the starter, so I checked that the fuel filler was sealing okay. The loud 'hiss' when I removed it suggested that was not the problem. Back to cranking and pumping the throttle and eventually she fired-up, after a fashion, after a long time trying. Quite happy to run at 1500 - 2000 rpm but dies if I let her idle. Engage drive and the engine just hasn't got the guts - it mis-fires like hell and dies rapidly. About five minutes cranking and pumping to get it started again and the same thing happens. I still feel no wiser about what might be wrong so I;d be really gratefull of any ideas. Thanks.
I spent a bit of time with the errant 190E today. Took off the air cleaner and generally checked around the intake and stuff like that. Everything looked okay - clean and moving freely - so I tried starting it again. No joy after about a minute's cranking on the starter, so I checked that the fuel filler was sealing okay. The loud 'hiss' when I removed it suggested that was not the problem. Back to cranking and pumping the throttle and eventually she fired-up, after a fashion, after a long time trying. Quite happy to run at 1500 - 2000 rpm but dies if I let her idle. Engage drive and the engine just hasn't got the guts - it mis-fires like hell and dies rapidly. About five minutes cranking and pumping to get it started again and the same thing happens. I still feel no wiser about what might be wrong so I;d be really gratefull of any ideas. Thanks.
MBWorld Fanatic!
Joined: Aug 2002
Posts: 2,753
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From: York, PA
2003 C230K Sport Coupe, 1986 190E 2.3
It is most likely the Water Temp Sensor. This sensor tells the CIS-E the engine temp so that it can actuate the cold start valve if needed and control the engine idle to speed it up for cold engine. This input and the air intake temp sensor on the CIS-E system are what the computer uses to control mixture and idle speed. Check that first. It is a 4 prong sensor on you engine. Should be black round connector with 4 pins. You test it diagonally. Two pins go to the Ignition module and two to the CIS-E system. There is a chart for it. Go check out 190revolution.com's forums for the table. Search for my username and Water Temp Sensor. You will find more info than you may ever want to know on that forum. And I have written a few things up for testing and fixing the W201.
