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.

[Baldguy]

Was the CPS a decent quality part as I had this on a past CLK55 and it was the CPS.... Just make sure its a quality part....

[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.

[595Heaven]

I’d suspect CPS as well. The ECU will stop the engine if it loses crank signal. Happened to mine and a new one cured it.

OE part is Bosch.

[GTRene]

car battery still top?
key battery still good?

cheap things to check.

[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

[sbk1972]

Ml55 driver here. I replace my CPS yearly. Easy to get too, passenger wheel, liner out, hidden at back of engine.

Get yourself an Autel coder reader and see the codes once the car cuts out. Mass Airflow sensor can also cause stalling, mine did and I replaced that 3 weeks ago. Also purge valve can have issues too. This is where the error codes will help.

One thing, which is mentioned about, do not buy cheap chinese parts. Also use Bosch and accept that these will cost more. I have gone done the cheap route and regretted it.

Simon

[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.

[devnull]

Read the codes, don't throw parts at it, although this does sound like a CPS getting up to temp and failing.

[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.

[anonymous-user]

So you know what the brand/cost of the CPS part that was replaced?

I ask because the OE part costs something like £110 retail, where clones can cost as little as a tenner. Not saying that you should fit the OE one, but if it's a £15 cheappy from the auto factors I wouldn't be ruling a duff sensor out.

[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

[595Heaven]

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

[sbk1972]

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

[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 :-).

[rev-erend]

Defo the CPS.

It's a cheap part that fail frequently.

[595Heaven]

Mr M said:

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.

Sorry - I did read the first post, but I'd still say CPS is prime candidate. Mine luckily gave up the ghost on my dirveway so no major drama. I swapped it out myself. A pain to access but simple enough.

Might be worth buying yourself a generic OBD-II code reader - they are as cheap as chips nowadays. As an example something like this: https://www.amazon.co.uk/VXDAS-Scanner-Diagnostic-...

I used mine when the CPS died and it reported a P0335 code - Crankshaft Position Sensor “A” Circuit Malfunction

A couple of posts about changin it here: https://www.pistonheads.com/gassing/topic.asp?h=0&...

[sbk1972]

MAFs are easy to fit. just a screw driver, undo a couple of jubliee clips, or fasteners swap it out. There are tons of youtube videos showing what to do.

Believe me cars are just large metal lego sets. Give it a go :-)

My MAF had some crazy readings, i.e. my code reader shows actual live readings as you drive along. I could see it was going crazy and causing the truck to stall.

When a CPS fails the ECU can not work out crank shaft position and wont fire up. However sounds like the CPS has been done so go for MAF.

Let us know how it goes.

SBK

[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.