SL-Class (R230) 2003 -- 2012: Discussion on the SL500, SL550, SL600

SL/R230: Slow startup with 2004 SL350

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Old Oct 7, 2016 | 03:13 AM
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Ken Silver's Avatar
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2004 SL350
Slow startup with 2004 SL350

My first post in several years! After selling my fifth SL - a SL500 - some 3-4 years ago, I recently decided to get a low cost SL as a runabout as I don't drive as much as I used to. Now, of course, things have moved on. All the cheap ones are all in the 50-60k miles age bracket and have costly ABC problems.

So I went for an SL350 and that's the suspension worry out of the way. I've had this one for a week but the problem is that it takes 2-4 secs to fire up each time. The engine turns over sprightly enough and runs ok otherwise. Just takes a while to catch. After it's warm it may start immediately, but even that's not guaranteed.

Even the previous owner said he was told by the owner before him to turn the key briefly then wait for it to start. So the problem seems to have been happening for several years at least.

Is this normal? I've never heard this happening before. It has done 55,000 miles so maybe plugs/tune is needed?

(The car is having the bonnet repainted so I'll show photos on its return).

Any ideas? I've searched and not found any answers yet.

Last edited by Ken Silver; Oct 7, 2016 at 03:17 AM.
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Old Oct 7, 2016 | 06:23 AM
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bb88's Avatar
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SL350
fuel pump problems
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Old Oct 7, 2016 | 04:37 PM
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Ken Silver's Avatar
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Hadn't thought of that. Will get the shop to check it out.
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Old Oct 19, 2016 | 07:06 PM
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Might turn out to be a faulty crank position sensor. The indie said that was the probable cause and a common problem, so have booked it in with them for a new one.

I'll follow up post-repair!

By the way, they said that the sensor often fails completely and then the engine goes dead. Since the problem has been over 4000km ago at least, I'm apparently lucky to get this far without it happening.

Last edited by Ken Silver; Oct 20, 2016 at 04:11 AM.
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Old Oct 19, 2016 | 09:21 PM
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If the CPS fails to send a signal to the ECU, it will shut off the fuel pump. Typically, CPS failures are "all or nothing" - not just a slow start.
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Old Oct 29, 2016 | 04:52 AM
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As expected it turned out to be a common problem, the crank position sensor. It was replaced and the engine starts first crank now!
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