Crankshaft position sensor OR camshaft sensor?

[fredzman]

Hi,
I have some symptoms:
* Small issue with engine stuttering. Both in low rpm and high rpm. It happens rarely, and only for a second, but it happens.
* I also think that the engine is not running as good as it should on low rpm.

Besides that, the engine is running/idling fine. Always crank on the first, both hot/cold (Except a -few- times it may crank 2-3 times before starting with hot engine..)

Diagnose give me a shadow error on Engine speed/Crankshaft position sensor.

After reading online I find my symptoms more likely to be the camshaft sensor(??) And I've read that diagnose can show you error on either of these sensors, when only one of them are going bad.

Now these OEM sensors are quite expensive, and I don't like to replace both of them if I don't have to!

What do you think based on symptoms? Alternatively any experience with cheap aftermarket sensors? If they work, I'll just replace both.

[alberttm]

I don't think with dead crankshaft sensor you will be able to start engine, so probably it's ok.

[Ed CT]

What are the CEL codes?
It's generally a bad idea to use non-OEM aftermarket sensors for important engine/system control systems. Go with BMW OEM - you either pay now or pay again later.

[edjack]

We Yanks have experienced spotty operation from most aftermarket sensors, including cam/crank. You may get lucky in your selection.

"Shadow error" = ? Do you mean "pending code?" If so, what was the code?

The crank sensor is responsible for detecting misfiring cylinders. The cam sensor is responsible for ignition timing. I suppose it is possible for either to influence the other; however, each sensor has its own trouble code.

You might also consider the possibility that you have one or more intermittently failing ignition coils.

[fredzman]

I've also been reading that motor don't start with bad crankshaft position sensor. Probably because it's responsible for detecting misfire (thanks for info edjack) and the DME won't allow motor start?

I don't have a check engine light (yet). BMW scanner use the term "shadow memory" wich probably is the same as pending code. So I guess it will have to reoccur a few more times before it's a real error code.

edjack; We Yanks? Spotty operation? I don't understand