Car Turned off Randomly

[Dice_980]

Was driving down hill and my car turned off out of nowhere made no noise. Put new spark plugs and checked to make sure sparks was coming out of each one. Checked to make sure fuel was coming out of the driver side fuel filter. Swapped the main relay for a used one I had laying around going to buy a new one to make sure it's not that. Opened valve cover gasket and checked to see if the chain was broken. Car will crank but not start on. Any ideas what it could be?
BMW 318i 1991 M42

[Dice_980]

Stomp test is showing 1444 which is no failures.

[DesktopDave]

If the CEL turns on, the main relay and DME are both most likely OK.

Check your crank sensor to make sure it's clean and close to the crank trigger wheel. Also check it for resistance. Should be about 680 ohms between pins 1 & 2 on the sensor pigtail. Let us know what you find.

You can also test the fuel pump and the fuel pump relay with a jumper wire. I'd be tempted to do a flow and pressure test too.

[Dice_980]

Crank Position Sensor - 546 ohms
Cam Position Sensor - 1258 ohms
Compression in each chamber starting from first - 110, 107, 115, 115
Opened up valve cover gasket and looks like no teeth have been skipped either.
Sprayed some starter fluid but still doesn't help out.

[DesktopDave]

Compression seems low - our engines should see between 130 to 150psi IIRC. Was the throttle blocked open during the test?

Fuel is flowing through the filter, but is it developing enough pressure? The rail should see close to 42psi if you've teed the supply line. A pressure gauge will read about 80psi on a dead-headed supply line.

Have you tried jumping the fuel pump relay socket to see if the FP relay isn't causing your troubles?

[Dice_980]

Yes i think the minimum is 146, but I am thinking the engine should at least turn on running poorly. No i believe I had the throttle open during the test. I need to go buy a fuel pressure test kit today so will be trying that out sometime later. I tested the Fuel pump relay earlier today, it clicked open and the resistance in the relay was .01 so am thinking the relay is fine. I will jump it later on as well to give that a try.

[Dice_980]

Still nothing on my e30 and has been in the shop for about 3 weeks now. They have tried a different DME and not sure what else they have checked but the last thing i know of is that they were going to try a different air flow meter.