E36 misfiring after long drive

[Saltybricks]

So after a long while of driving my car I’d say about an hour to 2 my car begins to misfire & then shuts off, this has happened a few times now & if i leave it for a while it turns back on & runs like nothing is wrong. It once happened & the car wouldn’t start until the next morning, I just have no idea what it could be & it’s driving me crazy any help would be greatly appreciated.

[Eric93se]

I would be its bad wiring somewhere, but could be a sensor. Use a scanner to read any stored codes.

Also could be a relay because a worn one will get hotter and be more intermittent, So I would test the DME relay and fuel pump relay.

[Eric93se]

You should be OBDII so when it dies, have a scanner handy to read the codes.

[ArNulis]

if no diagnostics equipment is present. start with the full service. oil, air, spark plugs. if problem persits check ground points and inspect wiring around hot engine spots. if still nothing and dont want to go to mechanic try new ignition coils, leads. after this point is like playing battleships blind you are just troughing parts at the problem and hoping it will fix it. like crank sensor, vanos and so on....

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[Renzo520]

Sounds like ignition coils or a main relay. The relay is cheaper and easier to test, if its just cutting power off its unlikely to throw a code, since its literally like you turning the key off. Next time it fails, check the relay temp with your hand, if its very hot its probably your problem. Also, if its the coils getting hot, running with the cover off will help the issue, easy test.

[MisterM52]

at first I was going to say look at your o2 sensors but now that I think of it, your crank and cam sensors may be going out. Has happened to be, it gets worse over time.