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Car Forum / Mercedes-Benz Cars / October 2005190 2,3E 1987 won't start
I've earlier had a few occasions, where the engine would not start, but only gave a few smelly poofs backwards through the airintake when stopping cranking. After waiting some hours, it would start and run smoothly without problems for a long period. Recently, it started to smell of gasoline, which turned out to be the EHA leaking. I replaced the EHA, but now the engine won't start at all, except the few poofs after stopping cranking - exactly the same way as before, except waiting does not help. Before just buing another EHA to try, is there anyone with some hints? /Jens What is the EHA? What does it do? Does this engine have a carburetor or fuel injection? The EHA is the Electro-Hydraulic Actuator. It is on the side of the fuel distributor. Yes, he has fuel injection. CIS-E to be exact. The EHA is an electric bypass valve that regulates upper and lower pressure in the fuel head according to the O2 sensor signal. It is not causing the no-start condition. Reach under the intake as far back as you can. You will feel a large [like 3/4" i.d.] U shaped hose that is connected to the bottom of the mixture unit and it gose back to the idle solenoid. See if it is connected on both ends. It just pushes on and it does blow off if you start the car with your foot on the gas pedal...... > What is the EHA? > What does it do? > Does this engine have a carburetor or fuel injection? Jens, Karl is a professional who knows these cars better than anyone else on this board; take HIS advice and check if the 19mm (inside diameter) hose is connected the the idle mixture unit and the idle solenoid. Apparently it can get blown off by a backfire. Thanks Karl. The hose is correctly in place (physically at least). I neither suspect the EHA to cause the no-start, althouth the condition became permanent in connection with replacing it. Other tests I did: - Checked fuel pressure by running fuel pump (jump fuel pump relay) and checking return flow of pressure regulator. Flow seemed OK and fuel pump current was 6,5 amps. - Checked cold start valve by energizing it. Spray was fine, furthermore indicating OK fuel pressure. I have not yet checked if it actually energizes during cranking. - Checked ignition by looking at the spark of a disconnected spark plug. Seemed OK (although I don't know whether timing is correct). /Jens Suggest you consider the timing - how it could have been changed. Backfires into the intake suggests an ignition timing issue may be the problem. This is also my feeling. With fuel and spark present, there should at least be some reaction. But what can make timing change so dramatically, that it fires at a completely wrong time? The timing chain could have jumped a tooth on its sprocket in which case the camshaft is no longer synchronized with the crankshaft. The ignition is usually driven off the cam - I don't know if that's so on this engine. On this model, the trigger signal is taken by a pick-up coil monitoring two magnets 180 degrees apart on the flywheel (rear of engine). The trigger signal is then very fixed to the position of pistons (and without any possibility of adjustment). So if ignition timing is wrong, it must be because the Ignition Control Unit (EZL) somehow triggers wrong on the input signal, either because of wrong signal shape (due to pick-up coil) or because of a fault in the control unit. Is there anyone, who has experience with this? Suggest you read through the posts starting October 19, 2005 under heading "300E Misfiring" for his engine had similar symptoms that were, eventually, diagnosed and fixed! I guess you refer to the OVP relay. I did check that earlier, but anyway I tried to jump the relay (shortcircuit terminals 30, 87L and 87E) and check voltages with no better result. Anyway, thanks for the hint (it may be necessary to return to it). |
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