Hi all,

Been dealing with this for a long time. Started in roughly early 2016. A month or two after I swapped in the E55 motor:


I put a new crank sensor in, but that was 4 years ago. That sensor was only about a year old when the issue started. The symptom appears to be different, so I haven't bothered ordering a new one (yet).

Sometimes it cranks first try. Sometimes it cranks on the 150th try. Sometimes I can sit there for an hour and it will never crank. When it does crank, it starts immediately like nothing is wrong. It never enters a crank-but-no-start situation.

I checked starter relay; which is attached to the K40 relay by the ECU. It's fine. I removed cover from the starter relay to engage it manually, in which case it will immediately begin cranking. However, if I do this, it doesn't start right away. It will crank and crank but eventually it will randomly fire up and start running fine.

So, I just replaced the entire k40 relay with a new OE unit from AutohausAZ. Issue is the same.

I had a clue from a user on Facebook that it could be a grounding issue that resulted from my engine swap. I did discover that the ground strap from motor mount to chassis was MISSING. It was still attached to my old engine, so I put it back on. While inspecting all other grounds, I did notice melted insulation on the other engine ground (from power steering pump to chassis) but the wire is still solidly connected. As a precaution I loosened and re-tightened all grounds under the hood, just in case.

The issue seemed to be greatly improved but not fixed. It no longer took 150 cranks, but now it never takes more than 5-10 cranks to start. And sometimes it will crank immediately.

I'm at my wit's end here. Completely out of ideas. I want to repaint the car, as 312k miles has been really rough on it, but it's utterly infuriating to try and drive right now. Any ideas?

 

Two things to try if you havent:

-lube the gear at the bottom of the transmission
-do you have a brand new key?(new style). Its a known issue with new keys. Apparently taping the sensor on it makes it work better otherwise itll cause intermittent starting issues.

 

I went down that rabbit hole of lubing the flywheel gear 2 years ago: I bought a can of spray lube, opened the window to see the gear. I got the engine running and hosed down the flywheel teeth with the spray grease until it was good and lubricated (probably overkill). No change, however.

It's a new key, but the first 1-2 years with that key were flawless. This issue didn't happen until a month or two after the 55 swap.

 

Looks like your ignition barrel doesn't cope with your new chrome key?
There's a glitch somewhere where you get a random hit or miss on start up?.

Can you take a snap shot of all your warning lights when the ignition is turned ON?
Seems like the US cars has more warning lights enabled and active compared to European cars.

 

sorry a bit confused, sounds like it was not cranking at all, then started cranking after you fixed the ground? now it cranks 5 or 10 times before it starts? if that is true then its definitely the lube on the flywheel, unless you use spec lube which only comes in a huge pail, count on going under every 6 months to apply. although i read that bmw sells a small tube, not cheap though.

if it is still not cranking at all, then change the CPS to start with. i'd also change the battery in the fob. i remember reading someone put masking tape on their fob and it started working right.

Any codes?

 

If i'm not mistaken; something related to the "EIS/EZL" switch with chrome key programming..!,,

if you have spare ignition system, you can easily figure out this issue..

-;ZAYED;-

 

No codes.

Key worked fine from about 2012-2016, but the battery is not required for starting car. Battery only powers lock/unlock/trunk feature. Try it, your key will start the car even with no battery in it.

What you see in that video is after I replaced ground wire. It's better, but still not completely. It's odd that it improved the issue but didn't completely solve it. I went out today and removed the ground and used steel wool to thoroughly clean the connections at both ends and it made no difference.

It will either do nothing when I turn the key (nothing = starter not engage). Or it will crank and immediately run. The issue appears to be something preventing it from always telling the starter to engage upon key turn.

Tried masking tape on key, no change.

Here's a video I made just now with the windows down so you can hear what's happening outside the car better.

 

I almost had same issues with my friends C43, replaced many things no luck,

till replace whole ignition system, everything back to normal,,

can't assure you that, but mostly Intermittent starting or failing key , causing by bad "EIS/EZL" switch..!!??!!

-;ZAYED;-

 

When lubing Inwould think grease/paste is what you want. Spraying it wont help. Stuff gets hot down there and it all probably burns off in no time if its just spray.

 

is this mostly in the ignition unit in the dash? and to replace, I must buy new from the dealer because it's coded to the VIN?

 

Could be 100 different things. It needs to be diagnosed properly otherwise you're just throwing parts at it. Possibilities are all over in many different systems, starter system, drive authorization system, wiring, even neutral safety systems.
If problem can be duplicated it will only take a competent technician one hour of labor to diagnose. This stuff isn't rocket science or voodoo. Never will understand why people are so reluctant to have someone who is a pro at these cars with all the test equipment and years of experience and knowledge diagnose them. Proper diagnosis is always the most cost effective and best way. Anything else is a waste of time and money.

 

Ignition system contains:-

"ECU/EIS/ESL/Key", these should to be together,

if you don't have these (as a set of ignition),

you can pull out your current EIS with a key, and send it to any good ignition key programming,

my friend had problem with his chrome key last year, sent his EIS with old key style,,

after new coding & programming, no any issues..

-;ZAYED;-

 

Which is why I've been dealing with it for 3 years instead of throwing parts and money at it. I've been looking for a proper way to diagnose. The only things I've done are easy and cheap.

And both my indie mechanic and dealer won't bother unless I let them immediately replace starter and/or EIS. And on a $3500 car, I don't want to spend $2500-3000 on the off chance that it fixes the issue. I want accurate diagnosis before I sign a check, but I get told "well we cannot be sure your EIS is good until we just put a new EIS system in it." Not a satisfactory answer.

 

Sorry to hear about all these issues
Never had a starting problem, except a couple of days after I purchased the 43, when the CPS died and wouldn't start when hot, but started fine when cold. Changed the part and no more issues.
I have never lubed the starter ring either in the 9 years of ownership. I could just be a lucky owner

 

so no problems with the old key?

 

From what I remember theres an option in the instrument cluster to display if das has a start error. Might be helpful to show what the problem might be

 

reviving this old friend now that I found a new clue:


As you can see in the video, if the key is "down" while turning, the car will not start. If I push "up" on the key as I turn it, the car starts. You can also see how this corresponds to power at the blower fan. If the key is "down" the blower fan reads no output on the HVAC display. If I push "up" on the key, the HVAC shows power at the blower on HVAC. The same thing happens for turn signals and cruise control: if key is "down" they don't work, if key is "up" they work.

This would all indicate something up with the EIS tumbler the key is turning and my basic instincts say it's a simple solder joint (or two) in the EIS tumbler.

 

thats pretty interesting, there's a setting in the instrument cluster so that it says START ERROR everytime you turn the key and nothing happens if you think you have an intermittent eis issue. Or at least thats what i think its for...

 

know how to activate that? I've never heard of it

 

you need a star computer but its an option in the instrument cluster menu

 

I had a very similar issue with a 2005 SLK55, had the EIS replaced and it was fine after that.

I don't remember it costing THAT much, maybe $500? It's been a while though....

 

the entire EIS? that would require replacement of tumbler, immobilizer, ECU, and I think 1 or 2 other EIS components

or did you mean just the EIS tumbler that the key plugs into?

 

Sulaco, have you come across the DAS documentation in your research? Replacing just the EIS with tumbler (sounds like that is what is worn out and fails to hold the key in the correct position) can be done without having to replace the other modules in the driver authorization chain. Buy it has to be via the dealer is the way I read it.

PM me and I can hang the document on Google Drive and share.

RHiatus1

 

Sulaco, have you come across the DAS documentation in your research? Replacing just the EIS with tumbler (sounds like that is what is worn out and fails to hold the key in the correct position) can be done without having to replace the other modules in the driver authorization chain. Buy it has to be via the dealer is the way I read it.

PM me and I can hang the document on Google Drive and share.

Hiatus1

 

Yeah, seems that EIS internal harness went bad,

if i'm not mistaken;

can't replace EIS alone, have to get "EIS/ESL/Key", and coded to the ECU..!

-;-ZAYED-;-