Shutting off randomly..completely shutting off. And won't start up

[lolcantturn]

Here's a background on my E30
Changed headgasket (and every other gasket included in a headgasket set) which was correlated to my overheating problem
changed sparkplugs
changed thermostat

It was running fine 2 days ago right after I changed the gaskets.
I noticed on WOT I would get misfires near 5.5k RPM, like the "pop pop pop" on two-step systems, but it only did that sometimes.
I have an arching between my connections on the distributor cap, but it only happens like twice a minute.

So anyway, I was driving around for about 10minutes, it was raining and it was cold, and I just stopped at a stop sign. I go, and about 4 seconds later, "Check Engine" goes on, and my RPM's start to go from 2.5RPM to surging through 1.5-2.5rpm. Then it shuts off.
I return later with my dad's car as the rain just calmed down. I return about an hour and a half later. I try to start it up, nothing. On top of that my battery's low so there's not enough "push" to really start it up if I tried again.
Pop the hood, jiggle some wires between the spark plugs and the distributor cap, hoping something was loose.
I put jumper wires so I can charge up the battery so I can have more push. Turn the key, and it turns on instantly? So I drive it home, no problem.
I kept the car running in front of my house to charge up the battery. I left it there for about 10 minutes. Then I got in, turned it off, and turned it back off to see if it would die on me. It didn't.
So I go about 200 yards, in 3rd gear at 35mph, and then my RPM's start to become erratic again! I'm like "Oh yeah I'm gonna save it this time," so I downshift to 2nd, hoping to keep the engine running, it's still surging and obviously wants to die. I put it in 1st, and the rear tires lock up (because the engine is dead) and now I'm sideways in one of the busiest intersections in my town. Thank god the E30 is light, pushed it with ease.
Oh it was still raining calmly and it was cold. My lights were on but my wipers werent, I was trying to conserve battery.
Now it's stuck there, parked. It's not starting up, I tried to charge the battery to give a little more umph, but nothing is happening.
I'm clueless. Help?
sorry for the long read, I was trying to be as detailed as I could be.

SPARKNOTES:
Car misfires sometimes in WOT. It was raining, car shut off even in gear. It starts up much later, and I drive it around, car shuts off still in gear. It doesn't start up anymore.

[lolcantturn]

Update: I went back to my E30 after 45 minutes and it started up. I went like 300yards, and In third gear. I downshifted to 2nd to make a turn and it shut off right then and there! I'm kinda suspecting the car shuts off as it warms up. Now ever since I changed my headgasket and therm my temp gauge doesn't go past blue really, so the car only warms up a little but I don't think that's correlated

[iwantspeed]

check things individually and see if they help. if you do all of these at once with out a test drive in between you won't know which actually fixed your problem.

engine ground strap
voltage regulator on the back of alternator (just for the heck of it)
crank position sensor
ecu
that the ecu is properly bolted up to the bracket
that the temp sensors are fully plugged in( there is a blue sensor and a brown sensor at the front of the motor near the thermostat)
you didn't mention what kind of e30 you have.

if you have an 325I
you will have a crank position sensor on the front of the motor
it can be seen on the passenger side of the engine bay and it has a bracket near the ac bracket that holds it on.

it plugs near the c101 connector at the front of the motor not the one near the fuse box.

you can use a multimeter and check the ohm spec of the crank sensor.

here is a picture from when I checked mine.
i was tracking down a similar issue.(ended up being the ecu at fault, short on the circuit board.)

you can try swapping out your ecu for a know good used one.

[hotballs]

fuel pump. Take the hose off the fuel rail, put it in a cup, crank the motor. See how much fuel fills up the cup. If none, then fuel pump. There is a certain amount of time/liter in the bentley.

[lolcantturn]

check things individually and see if they help. if you do all of these at once with out a test drive in between you won't know which actually fixed your problem.

engine ground strap
voltage regulator on the back of alternator (just for the heck of it)
crank position sensor
ecu
that the ecu is properly bolted up to the bracket
that the temp sensors are fully plugged in( there is a blue sensor and a brown sensor at the front of the motor near the thermostat)
you didn't mention what kind of e30 you have.

if you have an 325I
you will have a crank position sensor on the front of the motor
it can be seen on the passenger side of the engine bay and it has a bracket near the ac bracket that holds it on.

it plugs near the c101 connector at the front of the motor not the one near the fuse box.

you can use a multimeter and check the ohm spec of the crank sensor.

here is a picture from when I checked mine.
i was tracking down a similar issue.(ended up being the ecu at fault, short on the circuit board.)

you can try swapping out your ecu for a know good used one.

fuel pump. Take the hose off the fuel rail, put it in a cup, crank the motor. See how much fuel fills up the cup. If none, then fuel pump. There is a certain amount of time/liter in the bentley.

Thanks guys! I'm going to try all you said tomorrow. Quick questions
Where is the engine ground strap on a 325is 1988?
Where's the ECU on the same car?
And where's the fuel pump?

[lolcantturn]

The thing is, I'm not exactly sure how I would diagnose the problem...Am I just supposed to drive the car until it dies and hopefully find parking, push it and leave it there, return an hour later and start it back up? :???:

[jlevie]

The first step would be to run through the fuel system tests in the Bentley manual.

[AmosTheRocker]

This EXACT same thing happened to my wife's car about a week ago. Cam sensor tested low. Removed it, cleaned off some metal shavings (my guess is starter shavings). Replaced the (now clean) cam sensor, tested great.

The car as been running fine all week.

[lolcantturn]

The first step would be to run through the fuel system tests in the Bentley manual.

Will do, thanks!

This EXACT same thing happened to my wife's car about a week ago. Cam sensor tested low. Removed it, cleaned off some metal shavings (my guess is starter shavings). Replaced the (now clean) cam sensor, tested great.

The car as been running fine all week.

Where's the cam sensor located? Let me guess, it's the same as the crank sensor?

[lolcantturn]

Bump

[Dude]

Try jiggling around the relay's too, there the square shapped fuse things in the fuse box between the regular fuses

[StereoInstaller1]

Where's the cam sensor located? Let me guess, it's the same as the crank sensor?

I thought you have an M20? If so, only crank position sensor, no cam position.

Sounds to me like (once again) main relay.

"car runs fine but dies suddenly, will not restart yet starts again just fine later"

Well over 20 cars on R3V alone this year have been just this...but you may have other issues as well.

[lolcantturn]

Try jiggling around the relay's too, there the square shapped fuse things in the fuse box between the regular fuses

I thought you have an M20? If so, only crank position sensor, no cam position.

Sounds to me like (once again) main relay.

"car runs fine but dies suddenly, will not restart yet starts again just fine later"

Well over 20 cars on R3V alone this year have been just this...but you may have other issues as well.

Thanks, I'll try to clean the relays with CRC electrical cleaner and hope they're not dead.
The crank position sensor, where is it located? Is it in the picture above?

[lolcantturn]

After searching a bunch of threads I've concluded it's this in this order:
Main relay
Fuel Pump Relay
Crankshaft Sensor
Fuel Pump
ECU

Can I buy either of those relays at a generic auto store? I'd really like to get my car going by tomorrow.

[mr.vang]

mine was doing that too when i first bought it. i knew it was the fuel filter so i change it and now it start every single time.