Car goes into lower RPMs and stalls

[ugaexploder]

Started my car in the garage and went to clear the SMG code before taking it to the smog shop. AC was on and it nearly stalled, when I remembered the no AC experiment, so I decided to suck up the heat and get a data point.

Drove it around town mostly skipping even gears, primarily to keep the SMG pump happy, but also because the 3rd -> 1st shift coming to a stop is what seems to maximize the potential to make the car stall at stops signs and red lights.

Not a single RPM dip the whole time and no surging idle at startup.

the picture i posted above is what my AC compressor looks like. I think the bolt with the non-existent wire hanging off of it is for the AC compressor clutch. I don't think the frayed wire is too much of an issue, but I think mine may be related to that compressor clutch wire being gone.

awesome to hear the car started acting right!

[nahvkolaj]

Started my car in the garage and went to clear the SMG code before taking it to the smog shop. AC was on and it nearly stalled, when I remembered the no AC experiment, so I decided to suck up the heat and get a data point.

Drove it around town mostly skipping even gears, primarily to keep the SMG pump happy, but also because the 3rd -> 1st shift coming to a stop is what seems to maximize the potential to make the car stall at stops signs and red lights.

Not a single RPM dip the whole time and no surging idle at startup.

Update: drove it to the gym and had an RPM dip coming to a stop sign. Not stall worthy, but AC would have exasperated the issue. I think the AC being on just makes whatever vacuum, fuel, or sensor issue I have more apparent.

I did a VANOS test with Tool32 a couple weeks ago and it looked good. Probably doesn't give a good indication of a sensor not 100% but still okay.

[ugaexploder]

Would you be able to pop the hood and just take a quick look at your ac compressor? I highly doubt yours is in the condition mine is, but never know.

[nahvkolaj]

It's hard to get a good view with all the shrouds in place, but here it is. Pretty sure this connector is just for clutch engage/disengage and not a root cause.


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[ugaexploder]

I'm not talking about the connector. If you look at my photo, the bolt above the connector has a small piece of wire connected to it that has been severed.

Yours looks like its in fine condition though, so I don't think we are having the same issue

[bagger]

I just experienced my first stalls just today in parking lot traffic and making a 90 degree turn. Got it home and immediately looked for codes, and got this one: 'DME: switch chain, frictional connection" which was new to me. There are some threads here about this, and apparently it's related to the clutch switch. I verified that mine is crap via INPA because when I press the clutch in and out the "status grip switch" is always on (instead of being on and off). So there's another thing you can check out in your hunt to figure it out.

[sapote]

For my situation I honestly think the VANOS solenoid valves are all gummed up and possibly the filter is probably clogged as well. Just waiting on some strong rubber magnets and new crush washers to replace the VANOS solenoid.

If vanos has issue then codes should have popped up already.

[AWE46M3]

I just experienced my first stalls just today in parking lot traffic and making a 90 degree turn. Got it home and immediately looked for codes, and got this one: 'DME: switch chain, frictional connection" which was new to me. There are some threads here about this, and apparently it's related to the clutch switch. I verified that mine is crap via INPA because when I press the clutch in and out the "status grip switch" is always on (instead of being on and off). So there's another thing you can check out in your hunt to figure it out.

Yes sir - replace the clutch switch with a brown one (NLA, can be bought used on eBay for premium) or the Euro green one.

[sapote]

I have symptoms of possibly a bad fuel pump. There are times when I turn the ignition and it cranks but no start. Then I wait a few seconds and do it again And car turns on fine. The other day I was driving and I took a turn in 2nd gear and realized the car turned off while the clutch was pressed down. Now it’s doing it way more often when the car is running in slow speeds it just turns off but turns back on when I try again.

My guess is my fuel pump went bad but are there any codes that come up when the fuel pump is bad ? I will go home and run the codes and post them here.

Additionally, is the genuine bmw pump the only option we have which is what I see on fcp ? It’s $500 which is ridiculous. Any decent aftermarket options if I do have to replace it?

Does the cruise control work? I’m thinking a bad clutch pedal switch.