1995 BMW Engine Randomly Stalling

Question

Hi all.

I’m having some major issues with my 1995 BMW E34 540i m-sport, automatic, m60b40(v8) engine. The dash reads about +-140,000 miles, but engine was replaced by first owner(reportedly he hit a big puddle and engine flooded, insurance replaced the engine) and was only driven for two months thereafter before sitting for 14 years.

She sat for 14 years in the hot Southern California sun. The first owner, about 2 months after replacing engine, detected some drive shaft issues, but never got to fixing it. Through a excellent mechanic, I got her all fixed up and she’s been running on the road.

I’ve been searching through forms to try to find a solution to this problem, but it’s all over the place with answers, so I wanted to try to see if anyone here can help.

As of recent, she seems to be stalling(engine completely shutting off) randomly. Generally it occurs more when going slow speeds(1-15mph), in which I’ll have to come to a complete stop and restart the engine. But will sometimes happen when moving at higher speeds(20-65+ mph)(engine will cut off, everything on dash will turn off, but then everything will fire back on immediately, only when going higher speeds)

Here are some things I've tried:

Some forms said a possible major vacuum leak, so in a attempt to see where a leak would be, I had the engine running and sprayed brake cleaning fluid in areas where there could possibly be a leak to see if the engine would perk up, but nothing came out
I tried out an old feature on older bmws, the "stomp test". Basically it will give you morse code of fault codes through a simple procedure. It gave me only one code: "1213 Lambda Control System Bank 2: The ECM has been unable to maintain Lambda (fuel mixture or fuel trim) on Bank 2 (cylinders 5–8) of the engine.", I assumed this was due to me gutting one of the catalytic converters(it was blown out at causing back pressure) and the O2 sensor is getting bad info. I didn't think this was causing the issue, because the engine has no major misfiring. Correct me if I'm wrong!

I haven't tried much else out, as I'm unsure where to go from here.

It’s really strange, and I love the car and want to drive it, but I don’t feel safe with this issue. This is my first project car, and its a really rare car for its year and kind, so I really want to get her running smoothly.

Anyone have any tips? Feel free to shoot me any questions if you need more info!

Thanks!

scottykilmer · Accepted Answer

Man when I get that old it is a pain working on them you can only get limited data from a computer to analyze it so many things can go wrong. I would start with the basics like changing the fuel filter and pressure testing the fuel pump it could be the fuel pump is starting to get weak. Other than that gas your best bet is to find a guy like me who understands BMWs and has a pretty good BMW analytic computer to hook it up and analyze the live data