Stalling with no clutch sensor

[liam821]

Background: 04 M3 originally SMG converted to 6MT. 110k miles

Ever since I got my PY car, it likes to stall coming to a stop. Put the car in neutral coming up to a red light/stop and half the time it the rpms dip so low that the oil light comes on and then will or will almost stall. It's ridiculously annoying. I've gotten really good at keeping a close eye on the rpms and heal-toe the gas pedal at the same time.

So in my continuing pursuit to stop my car from stalling I've done the following:

a) Replaced the MAF
b) Ditched the aftermarket intake the car came with and replaced it with a stock parts
c) Cleaned the IACV, throttle bodies
d) Checked for leaks, none that I can see
e) Verified that the tune/dme has stock 6MT coding/tune
f) Car runs great, no hesitation, doesn't smoke, no weird noises

The car has no codes because, you know, that would be too helpful. I was searching around for other things to look for and I came across a thread here that mentioned that without a clutch switch when doing the SMG->6MT conversion the car will have a tendency to stall. Not sure why that would cause that, but let's have a look. Turns out my car has no clutch switch, and the clutch master cyl doesn't even have a place for the clutch switch to attach (see below). I haven't found any modified wiring as far as I can tell. SMG DME was still in the car, I unplugged it and removed it but it made no difference. Also, cruise control does not work - although I converted to a ZCP steering wheel which deletes the buttons so not having cruise isn't a big deal, although I'd like to do a Z4 cruise control stalk perhaps in the future.

Before I go to all the effort to replace the master cyl, install a clutch switch and wiring - is this worth my time? I can't think of anything else that could possibly be wrong.

Not sure what master cyl this is, it's not from an e46m3 because it's missing the clutch switch plate. Perhaps this is off another e46, I'm not really sure. (see pictures below)





ECS shows the clutch switch should look like this:

[eacmen]

You said you checked that it was a 6MT program, but is the tune stock. I have had idle stalling issues on bad tunes before.

Clutch switch can be coded out I think.


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[liam821]

You said you checked that it was a 6MT program, but is the tune stock. I have had idle stalling issues on bad tunes before.

Clutch switch can be coded out I think.

I pulled the DME code and sent it to somebody here on the forum who helped me verify it's stock - but I suppose he could be wrong. I'm not sure how to tell. I could probably flash a stock tune back on with ncs expert...

[heinzboehmer]

I pulled the DME code and sent it to somebody here on the forum who helped me verify it's stock - but I suppose he could be wrong. I'm not sure how to tell. I could probably flash a stock tune back on with ncs expert...

NCS expert won't let you flash tunes, you would need something like MSSFlasher or BMW Flash. Regardless, if you post up your tune I (and probably others) can help you double check that it's stock.

[sina]

I have the same issue, except I am 90% sure that it's a leak, since the sound is a bit off. I can't find any leaks when I take apart and put together the stock airbox, but the problem persists. I suspect there is something wrong with the clip on my vent hose on the under side of the manifold.

[liam821]

NCS expert won't let you flash tunes, you would need something like MSSFlasher or BMW Flash. Regardless, if you post up your tune I (and probably others) can help you double check that it's stock.

Here is a link to the dump which I grabbed with BMW Flash.

https://liam821.com/2004-m3-liam.bin

I have the same issue, except I am 90% sure that it's a leak, since the sound is a bit off. I can't find any leaks when I take apart and put together the stock airbox, but the problem persists. I suspect there is something wrong with the clip on my vent hose on the under side of the manifold.

I just had my intake manifold off over the weekend to replace the starter and doubled checked everything. It's tight and not leaking on mine, but yeah, if that is loose or off it would absolutely cause issues.

[heinzboehmer]

Here is a link to the dump which I grabbed with BMW Flash.

https://liam821.com/2004-m3-liam.bin

Yup looks like you're running a standard HP (facelift DME) US manual tune.

[liam821]

Thanks for double checking heinzboehmer !

[eacmen]

What clutch/flywheel combo do you have? Stock or lightweight? I had issues with this on a tilton triple disk clutch and had to raise the RPM. But it never really went away.

[NaM3]

I have this same problem too for a long time. My car have been converted to manual by Kaiv and I do have the switch chain error code. Will it help if I had that coded out?

[liam821]

What clutch/flywheel combo do you have? Stock or lightweight? I had issues with this on a tilton triple disk clutch and had to raise the RPM. But it never really went away.

I assume its a stock flywheel and clutch, feels like a stock clutch/flywheel package to me - but I don't know for sure.

I have this same problem too for a long time. My car have been converted to manual by Kaiv and I do have the switch chain error code. Will it help if I had that coded out?

It's possible its wired wrong, although Kaiv knows whats up. Does your cruise control function normally? From my reading you can pull the codes and if you have "FC 50 IN DME SWITCH CHAIN FRICTIONAL CONNECTION" which apparently won't cause a CEL but will cause the car to stall. Having that alert indicates there is a problem with the clutch switch.

[NaM3]

It's possible its wired wrong, although Kaiv knows whats up. Does your cruise control function normally? From my reading you can pull the codes and if you have "FC 50 IN DME SWITCH CHAIN FRICTIONAL CONNECTION" which apparently won't cause a CEL but will cause the car to stall. Having that alert indicates there is a problem with the clutch switch.

I need to check my codes again. I do not get a CEL but the code is def there.

And yes my cruise control works normally

[mrgizmo04]

My car is original 6mt. After a couple of track days this year I started having code 50 for switch frictional connection. I looked at the switch, nothing leaking onto it, I still replaced it. Still got the code. Code sets rather quickly after clearing it, dont even need to drive the car. When it sets, it's noticeable the car starts idling just a tad rougher and rpm drop by around 50 but stay stable (idle not hunting). I only got the car to really drop rpm and shutdown a few times at the track in 110+ ambient. So something is cooking.

I also heard that GPS in the tranny can cause that behavior. I swapped to an older GPS i had laying around. I did notice some tranny fluid coming out of gps. Easy to do without dropping the tranny with a 22mm (box end fits the wire through and onto the sensor). I will see if I get the code back after this.

The other thing that I noticed on mine... When i was messing with clutch sensor switch I left the footwell cover off for a few days. There seems to be a bad electrical connection somewhere in that loom (where obd connection and footwell light and other wires are on the left side). My driver side footwell light would sometimes not come on unless I move the loom around. I believe I was also able to trigger the code by moving the wires around under there a few times with car running. Might be something shorting and having a bad connection. Old car, old wires.

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[liam821]

Meh, I'm not really sure what to say. I guess I'll buy the misc parts to get the clutch switch wired and see what's what - it's the only thing I can think of. If I go through all the effort and the only thing that comes out of it is I need to push the clutch in to start the car I'll be a bit bent. It's just my car's way of telling me to never stop and drive fast....haha

I'll report back here once I know more...

[George Hill]

Hey guys note that the M3 needs the orange clutch switch, they are different for M3 and non-M (which is black). If you look up the part number for the M3 and search it with BMW or all the major parts suppliers (I have seen) it will supersede to the Non-M switch which will not be correct, you have to physically tell the parts person to order the first number.

The correct M3 pn is 61-31-9-122-700, the Non-M (which is wrong) number is 35-42-6-876-898.