W220 Intermittent ignition problem

[desertfox]

I've got a real 'interesting' problem with my W220 S320CDi (2005) with about 80k on the clock (at least allegedly):

Two symptoms:

1. intermittent ignition issue. The car unlocks normally, the key turns correctly, the main lights on the instrument cluster come on. I can hear the electrics in the console (comand etc) whizzing into life. Sometimes the instrument lights (and parking sensors etc) do not come on at all, and there is no sign of ignition. Occasionally I can see the lights come on briefly, and then are extinguished very quickly. If i use the remote, to lock, unlock and then retry, then after a few such attempts it will come back normally. It could take 1 to say 5 attempts to work correctly. Other times, the instrument lights come on, stay on and ignition is normal. It seems to come in waves. Can be normal all week, then one day it starts playing up for a while, and then can be normal for several days again.

2. very occasionally the engine dies while driving, could be 80 mph on the motorway, or could be pootling around town. Stop, turn off, turn on and it restarts. Feels like it is related, as if the immobiliser just randomly came on and ceased ignition.

Any ideas what is going on?
I've not been able to find threads with similar symptoms - hopefully I've not missed any.

Thanks, Andy.

 

[desertfox]

nobody?

 

[mercedes13156]

Dying at 80mph, er even pootling about in traffic is not the ideal situation. Sounds like you need codes and live data read. Get it on STAR before the car kills you and anyone else in it.

 

[Craiglxviii]

What he just said ^^^

Let the car tell you what is happening. Find a local STAR equipped indy (use the Specialist Finder on this site) and shell out £40 to get codes read pronto. Then the indy can diagnose what is wrong.

In Warrington you have a choice of several good, reputable, local indies, some of whom post on here regularly.

Edit- here because I'm a softy:

MB Tech - Warrington


Unit 24,
Craven Court,
Winwick Quay,
Warrington,
Cheshire
WA2 8QU

T: 01925 653050

 

[television]

Do check the red lens on the end of the key, make sure it is clean, shine a light down the ignition switch to check all clean.

Certainly worth have the codes read out, they could give a clue as to what is going on.


Engine cutting out could be the CPS, but a bit early to be sure.

 

[desertfox]

What he just said ^^^

Let the car tell you what is happening. Find a local STAR equipped indy (use the Specialist Finder on this site) and shell out £40 to get codes read pronto. Then the indy can diagnose what is wrong.

In Warrington you have a choice of several good, reputable, local indies, some of whom post on here regularly.

Edit- here because I'm a softy:

MB Tech - Warrington


Unit 24,
Craven Court,
Winwick Quay,
Warrington,
Cheshire
WA2 8QU

T: 01925 653050

It did show the problem once when in for a service at a local MB indy. They said they would check the codes, but as far as I know nothing was found - the guy who handed it back to me actually didn't have the results. I understood that this is typical of EIS issues though - nothing logged.

It may be coincidental, but for the last few weeks i've been making sure everything electrical was in an off state when I switched off the ignition - i.e. a/c, radio, auto-on lights etc etc. Not done it again in more than 2 weeks now, so I'm a little hopeful that there is some sort of drain on startup (i would suspect a/c fan would cause most drain) which causes it to happen. Could simply be battery in that case, of course.

That wouldn't explain cutoff on the motorway but I don't think that has happened since I was advised to take any other keys off the fob to avoid physical pull on the key away from the EIS. So these could easily be two separate issues.

Thank you all for the responses. I will let people know how it goes just for people who might find a similar issue.

Thanks,

 

[television]

If the worst comes to the worse you can send the EIS switch to Mark in the midlands, he can repair most of these.

 

[desertfox]

It did show the problem once when in for a service at a local MB indy. They said they would check the codes, but as far as I know nothing was found - the guy who handed it back to me actually didn't have the results. I understood that this is typical of EIS issues though - nothing logged.

It may be coincidental, but for the last few weeks i've been making sure everything electrical was in an off state when I switched off the ignition - i.e. a/c, radio, auto-on lights etc etc. Not done it again in more than 2 weeks now, so I'm a little hopeful that there is some sort of drain on startup (i would suspect a/c fan would cause most drain) which causes it to happen. Could simply be battery in that case, of course.

That wouldn't explain cutoff on the motorway but I don't think that has happened since I was advised to take any other keys off the fob to avoid physical pull on the key away from the EIS. So these could easily be two separate issues.

Thank you all for the responses. I will let people know how it goes just for people who might find a similar issue.

Thanks,

not been a problem for ages, and then this week or so, started over again.
Same issue. 31st August taking a car full of people out at lunchtime, and 'nothing'. some lights on, but turning the key did not light the usual lights, and no ignition. Fiddled with it a while, on/off, on/off etc several times. Eventually locked car in embarassment, walked away, thought 'one more time', went back and then it started.
Since then say 30% of days it is giving trouble at some point. Another owner I spoke to (2007 W221) said he had the exact same issue, and the problem was the relay providing power to the ignition system after accepting the key turn. Anecdotal, of course. Anyone any idea which relay this might be because it sounds so plausible and would be a cheap thing to simply replace?

Of course if I take it to the garage it will undoubtedly behave, just to make me look a fool.

 

[desertfox]

Just wanted to impart what appears to be the solution - and a simple cost-free one at that. A throwaway comment from a fellow owner was that he had a similar issue, and the garage simply cleaned up and refitted a relay (he didn't know which), and the problem went away. I investigated both relay boxes in the engine bay, just out of curiousity, more than anything else, and lo and behold a number of the relays in the passenger side box were somehow lifted slightly. When you pressed them, they dropped about 2-3 mm further into their sockets. there were several like this.
Since then, I have not had an issue at all with anything electrical. Fingers crossed.

 

[Swino890]

Did you have any further issued since you reinserted relays? I'm having exact same problems as you.