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1992 300CE Hard Starts and Stumbles
The car now has around 153k miles. I've searched and have learned a lot, but most of the good threads with a lot of information come up blank when the original poster doesn't follow up.
Starting my beast is becoming an effort and is progressively worsening. Car has a full tune up: oil change, coolant temp sensor, everything related to cooling, plugs, wires, cap, rotor, coil, fuel filter, both fuel pumps, oxygen sensor, OVP Relay, and fuel/air mixture has been Mercedes master technician tuned with precision. No vacuum leaks anywhere. Fuel pressure is not a problem. I even engage the starter I click the key to on position and let fuel pumps build pressure. My fuel economy is right where is should be. Around 18-20 in the city and 23-26 on the highway. No stumbling at highway speeds. So the problems: Starting cold takes two tries. First crank fires up stumbles and dies. Second try takes about 5-7 seconds of cranking to get it firing regularly and it still stumbles and eventually evens out. When I step on gas stumbles all the way to 2k rpm or so. When the car is up to operating temp and I'm driving along it stumbles and feels like it wants to stall. If I pull up to a stop and roll through and step on gas it stumbles badly. Stumbles just about any time the RPMs are under 2k. Doesn't happen all the time, but happens a lot. Also, when at operating temperature and the car is parked and shut off for approximately 5 to 10 minutes it takes 6-8 seconds of cranking to start. I don't know where else to look. Is the CPS (Crank Position Sensor) causing this stumble and poor starting? Thanks a lot everyone.
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Allen Kroliczek Oak Grove Autosport | Oak Grove Autosport 01 G500, 82 300TD, quite a few more..... |
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The earlier symptom of a faulty CrankPS is difficulty starting when the engine is hot. But later, whether the engine is hot or cold, it just won't start with CPS problem. So I think you are right, go for the CPS first, and update us please
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Sounds like a fuel issue to me, of course low secondary ignition voltages can cause the same conditions.
Did you use Bosch cap & rotor? Has you tech had the car on a SCOPE? Fuel bleed-off is the most common cause of long cranking times.
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MERCEDES Benz Master Guild Technician (6 TIMES) ASE Master Technician Mercedes Benz Star Technician (2 times) 44 years foreign automotive repair 27 Years M.B. Shop foreman (dealer) MB technical information Specialist (15 years) 190E 2.3 16V ITS SCCA race car (sold) 1986 190E 2.3 16V 2.5 (sold) Retired Moderator |
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All parts have been replaced with new Bosch components as well.
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Allen Kroliczek Oak Grove Autosport | Oak Grove Autosport 01 G500, 82 300TD, quite a few more..... |
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You've replaced almost all of the fuel and ignition systems, so you must be getting close. I didn't see any mention of EHA (controls fuel adaptations) or fuel accumulator or fuel pressure regulator, all of which can affect hard starts. Even a failing fuel pump relay might be doing hinky electrical things. Although you've replaced the OVP relay, you probably know that OVP is nearly always the first suspect in such cases. That alone would justify checking it again to be sure it's a good one.
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1988 California version 260E (W124) Anthracite Grey/Palomino Owned since new and still going strong and smooth MBCA member Past Mercedes-Benz: 1986 190E Baby Benz 1967 230 Inherited from mom when she downsized 1959 220S Introduced me to the joys of keepin' 'em goin' There are only 10 kinds of people in the world--those who understand binary and those who don't Last edited by Cal Learner; 08-12-2009 at 08:04 AM. |
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From reading his posts, he's replaced the fuel accumulator. My fuel pressure is good. The car retains most of its pressure after being shut down for about an hour. I've checked the OVP and replaced with 2 known working ones, so I've killed the OVP being the problem. Injectors and seals have been taken care of in 2007. I'm left with a crank position sensor. My ex-mechanic father finally decided to help me out and he's thinking crank sensor as well. So I guess I might as well replace as it's a variable I don't feel like playing around with. The car is getting significantly worse as time progresses, so it may just be the sensor.
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Allen Kroliczek Oak Grove Autosport | Oak Grove Autosport 01 G500, 82 300TD, quite a few more..... |
#8
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Crankshaft Position Sensor fixed the problem! The car runs and takes off like a bat outta hell. Life is good again.
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Allen Kroliczek Oak Grove Autosport | Oak Grove Autosport 01 G500, 82 300TD, quite a few more..... |
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