My engine randomly shut off on the highway.

[O 16581 72452 5]

I don't know WTF this was about, i was cruising along and suddenly my tach dropped to 0, no dummy lights or anything until i disengaged the clutch and the engine came to a halt, then everything in the dash turned on, engaged the clutch and the lights again went off. Did this a few times with the same results until just as random as it shut off, it kicked back on and i was on my way...

[Mastrcruse]

We had the same problem with my brothers E. We had it inspected and ours happen to be the Idle control valve. The little screw would screw itself in the unscrew itself, lean/rich, lean/rich. I remember going on the high pushing in the clutch, everything turned off, let the clutch out a boom started itself back up and did that A LOT! Fixed it and symptoms are all gone.

[O 16581 72452 5]

Heh, that's crazy it would do that, i'll look into a new IACV because the engine does what you're describing.

[moatilliatta]

mine had that happen one weekend and then went away. i thought it was fuel pump or fuel pump relay. but it came back on after like 7 min.... it was quite strange.

[O 16581 72452 5]

Seems to me it'd be ignition related since the tach works from an ignition signal. It didn't matter how high the engine was spinning (disengaging the clutch in different gears), the tach didn't move.

[James Crivellone]

In order of possible failure

Bad Main Relay
Bad Speed Ref Sensor
Bad ECU

1 is the most common

[O 16581 72452 5]

In order of possible failure

Bad Main Relay
Bad Speed Ref Sensor
Bad ECU

1 is the most common

I had a car with a bad main relay and it acted differently, it wouldn't randomly shut off, it'd randomly not start or start, but it wasn't a BMW. Would resoldering it take care of the problem?

[moatilliatta]

mine has acted fine since then... i also thought it could have been main relay.. i swapped them out and still had a problem.

[emi325i]

check the injector harness, too. make sure the connector's all the way in ,and twist the lock until it clicks.

[Mike325]

My car did this and it was the main relay.

[O 16581 72452 5]

I can try resoldering it to see if it helps i 'spose, it's free.

[moatilliatta]

I can try resoldering it to see if it helps i 'spose, it's free.

resoldering what?

[O 16581 72452 5]

resoldering what?

The main relay consists of many solders that over time can crack (may not be visable) sometimes they don't get a good contact and resoldering them solves this. I don't know if it's a problem in these cars, but other cars i've had have had this problem, resoldering took care of it.