Engine Dies, Starts Up After Sitting a Few Minutes.

[jcatjake]

Hi I'm new here. I've searched through the forum and saw a few helpful threads, but nothing that covered my problem exactly. I'm more of a tinkerer than a mechanic so hopefully this makes sense.

Anyways here's the deal, My '91 318is has ran great with no real issues in the 3 years I've owned it.

A couple weeks ago I was sitting at a red light and the engine died. It would turn over when I turned the key and sputter a little bit but not start. I pushed it into a shopping center parking lot & popped the hood, nothing looked obviously wrong. I jiggled some wires, turned the key and it started right up. I figured it was some kind of loose or corroded connection.

The next day it happened again on the freeway, not idling this time. Instead of messing with the wires I called AAA. While waiting for the tow truck I turned the key & it started right up. My house was off the next exit so I drove it home.

I checked all the fuses & connectors. Unplugging plugging back in etc. Took it for a drive & it happened again. It seems to do it after about 5 miles or so.

I took it to a mechanic who admittedly said it might not be the problem but the front crankshaft seal was leaking oil on to the crankshaft position sensor. I had them both replaced.

I just now drove her home and low and behold that wasn't the problem (at least that leak is fixed though).

~7 miles later stalled at a red light, wouldn't start. I put my hazards on, waited 3 minutes and it started.... 

Any Idea's? There seems to be a lot of m42 wizards here. This seems like a gremlin of sorts. I'm looking forward to daylight tomorrow, some other threads had some helpful hints with other similar issues not specific to this one though.

Thanks

tl;dr see title

[axisofjustice]

I had the same issue. It was much more random. I had a shorted wire that was on the passenger side that somehow would cause my stall/nostart. I found where my wiring came loose and taped all the connections, I had no carpet and someone had kicked the wiring around a bit. My car is a project car so it was a mess at the time, and I blamed many things. Check to see that there is no short in front of the passenger seat where the harness runs across the floor tot he side of the car. No idea what wire as 3-5 were shorted in my car, so just a general inspection did the trick and I've had no issue since.

[DesktopDave]

When the car dies, do all the other electrical systems still work? Is the key switch still tight? Any installed anti-theft system?

If the rest of the car works, I'd be interested in the fuel pump and main relays. They are wear items. I'd also test the new crank position sensor; pins 1 & 2 should give you ~680 ohms resistance. I have had brand new parts that were out of spec. I'd start troubleshooting the fueling system given your symptoms. If you retrieve the codes, fuel system problems might report O2 codes like 1215. If you see a 1444, it's more likely a power or crank sensor thing.

You could also have a fuel pump on the way out, or a plugged fuel filter. They don't last forever, especially given the alcohol blends that pass for gasoline here. A pressure & flow test might be a good idea. The fuel pump connector under the rear seat can also loosen up.

Another less-likely possibility is some kind of momentary DME power outage. You haven't jump-started another car with your E30 recently, have you? The DME pulls power from the battery via the smaller positive wire off the battery, not the big thick one. There is an inline fusible link (wrapped in some thick shrink wrap) near the passenger rear wheel well that can be damaged by big power surges.

[jcatjake]

Thanks for the advice.

All electrics work, no anti-theft, key switch is a little loose but it's always been that way.

I messed with the connections under the back seat & the DME fuse link off the battery & other wires while the engine was running. Everything seems tight, car didn't stall. I cut the ignition, turned the key 'on' & it's throwing a '1444' code. Which I found thru this board means 'no fault'. I then took it for a 20 minute drive so I could check the fault code if it stalled (thanks to user kowalski's for his 'fault code' post). No stall this time, Murphy's Law... I need to get back to work now. I'll drive it further later when I have more time. Those codes will come in handy, I wish I found this board sooner...

[DesktopDave]

We'll stay tuned.

Those codes are very rudimentary...they tend to be a hint as to what the real problem is, rather than the problem itself.

[ryanjv]

I don't' know if it was coincidence or relevant, but i had a similar issue a couple years ago. 

Basically, when i was doing a whole lot of cleaning and tidying up under the hood (mess under the intake, etc), i noticed there was an extension cable on the connector to the airbox.  I took it off (it was like 8 inches) and i found that it still reached and connected.  I just thought, "well that's redundant" and got rid of it and tossed it in my trunk.

For the next week, i kept having the same issue where it wouldn't start or it'd start and die then after a few minutes it'd start up fine, only to die again a half hour later.   A 4 hour drive to pittsburgh took me 7 or 8 hours from all the dying and whatnot.  I could figure out what was going on and my friend thought my car was a death trap and she was afraid to go back in.  While there, i started poking around to see what could be the issue.  Frustrated, i just plugged it in as a hail mary and just to stop it from moving around in my trunk and everything went back to normal.  I guess it's resistored or something?  because at the end of my poking and prodding, the only change i made was putting it back in.  it never came back again

long story short, do you have the extension plug that goes to the MAF, because i think you should, unless it was coincidence.

[DesktopDave]

Basically, when i was doing a whole lot of cleaning and tidying up under the hood (mess under the intake, etc), i noticed there was an extension cable on the connector to the airbox.  I took it off (it was like 8 inches) and i found that it still reached and connected.  I just thought, "well that's redundant" and got rid of it and tossed it in my trunk.

For the next week, i kept having the same issue where it wouldn't start or it'd start and die then after a few minutes it'd start up fine, only to die again a half hour later.   

That is a resistor pack from BMW - one end of the cable has a little inline plastic housing under the rubber boot. It was a BMW service campaign to improve idle quality, believe it or not. I had the same item in my car, thought the same redundant thought, and pulled it out. Glad I did - the end that connected to the AFM connector was filled with water, causing a no-start. The car has run well ever since!

A 4 hour drive to pittsburgh took me 7 or 8 hours from all the dying and whatnot.

Are you sure your car wasn't trying to tell you something about Pittsburgh? 

[ryanjv]

haha probably.   Not a fan of the city, but we rarely go into the city.  My inlaws are off McKnight near Ross Park Mall.

Are you saying that when you took it off it made things better?  why would it make mine worse?

[Warsteiner]

My $$$ is on the fuel pump electrical connection under the cover plate under the back seat. I had the same thing happen to mine. I only found out about it when I broke down after stopping at a store to buy a lottery ticket and then called my friend and master mechanic, Don from MRMCar, who lived right around the corner. He found the electrical issue on the connection itself. There is no fix for it except to replace the entire unit which I did and problem solved. I had already replaced just the fuel pump so needless to say I have a spare now. I'm running with the stock unit from what I have heard is a very robust unit.

To see if that is really the issue, drive around with your back seat out and smack the snot out of your cover plate over the connection and see if it keeps running or starts back up.

Just my .02

HTH...
Cheers,
~Ralph