SLK 55 2010, random engine stops

[Mr M]

Any other owners of the same year experienced this ?
I have posted on SLK world but thought I'd ask here assuming that parts are shared with other models of the year. So, as per title really. Engine just cuts out, usually within 10 minutes of driving. Mostly at low speeds, like today at school chuckout time opposite the Cockfosters Rugby ground, but recently whilst doing 40mph, but that time I instinctively put my foot hard on the accelerator and miraculously, it spun up again. Not fun with a heavy engine up front and no power steering or brakes. Crank position sensor done this year. New battery this year. Routine spark plug change next year but no signs of any issues there. There was one other chap on the SLK forum who's had similar and his is a '55 of the same year. Shall be giving the garage a call anyway.

[Mr M]

Well, I had the CPS done around the Spring I think it was and I did that because on one or two occasions I had an issue where I would start the engine and after a minute of not moving, it would just cut out, also, shortly after driving off sometimes ; for instance, just after filling up one time (though that might have been post new CPS ). So naturally I was disappointed when it was still occuring after getting the CPS done. I would say, that it's staring to happen a little more often now which isn't great as it's quite dangerous.
It had the work done at Simon Light in Ware, so I've no doubt they would have fitted the correct MB part. Tricky one isn't it, as it's one of those that's difficult to reproduce at will :-\.
Additionally, sometimes I'll get in the car, turn the key full on and nothing happens. Do it again and it starts. Perhaps they are related. The joys of car driving.

[Mr M]

CPS has been changed this year by a top independent dealer so as far as I know that should be fine. CPS failure in my previous SLK would be hot restarting issues as well and I don't have that symptom.
New battery this year.
Key battery. Now that will be old but would that cause and engine cut out ? I've have just now replaced them in both main and spare which did need doing anyway so thanks for the reminder.

Edited by Mr M on Thursday 16th December 10:32

[Mr M]

> Mass Airflow sensor can also cause stalling
Yes that's one I had come across too. Sadly, I'm not a home mechanic so I would have to gather info from any previous peoples experiences and pass it on to the dealer (MB independent) to pin point the issue but thanks for the tip on the Mass Airflow Sensor. I'll look into that.

[Mr M]

I thinking reading the codes will be for the garage technician to do but they've still got to be able to reproduce the problem and get it on the machine in order to read the codes. Just to clarify, the car has had a new CPS earlier this year. My thoughts are that the problem lies elsewhere so I think a visit to the garage in the new year may be needed and they'll have to take it for a drive and try and reproduce it.
Anyway, thank you all for your thoughts on the matter.

[Mr M]

As mentioned further up in the conversation, the work was carried out at a reputable independent MB dealer, Simon Light of Ware. I think really we can probably put this topic to bed now otherwise it'll go around in circles.
For the record the part number was M0031532828

Edited by Mr M on Thursday 16th December 14:29

[Mr M]

595Heaven said:

Not sure why you’ve become so defensive. People are trying to help…

The CPS failure is a well known issue on the engine, and whilst it disables the car, it is a straightforward fix.

Hope you get the car sorted

It does help if one reads the details of the post first though, where I did say the CPS had been replaced at a reputable MB independent. Please don't don't feel I'm being defensive, hopefully, just logical... and thank you, fingers crossed I can get to the bottom of it.

Edited by Mr M on Saturday 18th December 11:19

Edited by Mr M on Saturday 18th December 11:23

[Mr M]

sbk1972 said:

Going to be Cps or MAF.

My local indy charges £80 to read codes, and that is literally putting machine on, reading codes. However this isnt correct. I tend to read codes, note them down, clear them then go for a drive and on my return read the codes again as these will be live / current. My indy would therefore charge me twice, hence why I now service my own car. I really cant stress how easy these readers are to use and how they pay for themselves.

Link below to code readers -
https://www.amazon.co.uk/Autel-AutoLink-AL619-Diag...

Ebay - MAF
https://www.ebay.co.uk/itm/115139321222?epid=20005...

MAF is an easy fit, just takes a screw driver.

Edited by sbk1972 on Friday 17th December 09:32

Great, thanks for that. As said I'm not really a home mechanic but if it's 'really' easy then I would give it a go :-).

[Mr M]

SBK - Will do, thanks. Been out for a couple of decent runs since changing the key fob battery (as suggested by GTRene) and the car has been behaving itself very well with perfect starts both times (no inactivity the first time of turning the ingnition on full either), so just keeping an eye on it.

[Mr M]

595Heaven\SBK1972,

Thanks for your earlier posts\suggestions. Just an update. Looks like the key fob battery change was irrelavant sadly. A few minutes after filling up this evening, at about 30mph the engine just stopped. No warnings. Just a dead stop. Instant power steering loss. So hazards on, lights off, turn of the key and it started again.
So that's two months after the last time it happened. At a high speed I think I'd be in trouble, so needs fixing.
Days past I would have bought the kindly suggested diagnositc tool, but not being someone who wants to collect too much stuff these days I'll probably look at the MAF fix and get the spark plugs changed as well.
I don't think I've ever had a car that just stops without warning before.
Chrs.

Edited by Mr M on Monday 7th February 21:48

[Mr M]

Thanks Juice. At the moment I'm on the Herts\Beds border so a bit of trek from you sadly :-\ but thanks for the offer.

[Mr M]

The reason I took it in to have the CPS replaced was due to the engine cutting out randomly as my previous 55 did a complete stop on me down the A1 but that had warm start problems as well before that happened. My current car doesn't have any starting issues which I believe are symptoms of a worn out CPS.
Anway, post CPS replacement it's still an issue although it doesn't happen regularly . Two months between the last occurance and the previous one. The only two similar circumstances were just after I'd filled up with fuel but that may be just coincidence. As a previous poster suggested, a fault meter would be useful but I'll see how it goes. Long journey shortly as well :-( as it's my only vehicle at the moment. I'm starting to feel a car just needs to be two things. Reliable, and practical. Getting old.

PS. My issue is the engine just stops dead. I don't have the luxury of a warning :-\

Edited by Mr M on Wednesday 9th February 20:25

[Mr M]

Ok thanks for the tips. I'll have a laymans check under the bonnet and see if the battery connections are all good. The live terminal easy access cover (red plastic one on the drivers side) has got a broken clip on one side so I'll check that too.

[Mr M]

Well, yes in a way. Down a long Dorset road on the 12th of Feb I was doing about 50mph. The engine cut, so I instinctively planted my foot on the accelerator and like the last time it happened at that speed (strangely, also in Dorset at the start of December), the engine picked up again straight away. So maybe it is accelerator related. But, it hasn't done it since. Having said that the car is normally only used about once a week for about 40 miles at the moment.

[Mr M]

Since the car has been back in a dry garage, I've had no on the road cut outs but very occasionally the car will cut out very soon just after I've started it up ie when I've just filled up with fuel, and move off. I believe the connection with the key to the ignition system is sometimes a bit hit and miss also. You'll plug the key in, turn it to position one and nothing happens. Take it out, and have another go and it's ok second time. So maybe a key\ignition communication issue. The chap that services the car did notice this the service before last and said to keep an eye on it. He always changes the key fob battery as well so it's not that.

Edited by Mr M on Wednesday 8th May 21:51

[Mr M]

Good research I'll have a look at those videos and make note of your findings. As you say, a total engine stop at high speeds could be quite disasterous.
PS I also do as you do if the first ignition is not successful. Take the key out, place it firmly back in and slowly turn to position one and this usually works second time.

Edited by Mr M on Saturday 11th May 14:07

[Mr M]

Nice work. I'm surprised more people haven't experienced this. It did happen to me again shortly after my last post here. Filled up wit fuel, started the car up, began to move off, car cut out. So we know where to look in more detail now. Cheers.