[jonesy_17]

2011 BMW 328i
2A37 - Valvetronic. eccentric shaft sensor plausibility
2A39 - Valvetronic, adjustment range

Have cleared a handful of codes but these two have since come back.
On cold starts, about 50% of the time my car will crank 2-3 times before it starts (other 50% it starts normally), then hovers between 1000-1200 rpm before leveling off at 600 after a minute.
No major starting issues besides this one, which is relatively inconsistent, and have yet to have any rough idling or regular misfires (I've read that these are also symptoms of a bad eccentric shaft sensor).

I assume the issue is from when they replaced the valve cover gasket. Oil must had already leaked into the ESS which is now causing it to start throwing codes but not enough for it to go bad. (they did the Valve Cover Gasket and the Valvetronic Motor already)

Should I go ahead and replace the ESS in advance or would it be fine to wait on it? (it'll cost me $1100 - $1500 where i'm at in SoCal)

[e90yyc]

If you’re seeing symptoms AND codes, I’d argue it’s no longer preemptive replacement. So I don’t think there’s any harm in putting a new one in before things get worse.

If you were doing it on a whim because you were in there already, different story.

Sounds like you aren’t going to DIY it?

[Papa Popov]

Never got a code from it, but before I replaced my ESS my car ran like dogshit on cold start. The whole car shook and sounded like a cammed LS for the first 30 seconds. Replaced the sensor when I did the VCG and haven't had any issues since.

From experience, the problem is only gonna get worse. I'd go ahead and replace it, but take a crack at it yourself before going to a shop. The job is time-intensive and a colossal PIA, but not difficult. Could even be done in an apartment parking lot (you'll get plenty of looks from your neighbors tho). Just make sure you have wobble extensions and a set of e-torx sockets on hand before starting.

[jonesy_17]

UPDATE: Replaced Eccentric Shaft Sensor and Valve Cover. No more issues.

[ccyccm]

How much did replacement run you?

I just replaced my ESS, along with motor mounts, and the car is significantly more powerful and smooth.

[e90yyc]

Originally Posted by ccyccm

How much did replacement run you?

I just replaced my ESS, along with motor mounts, and the car is significantly more powerful and smooth.

More powerful? No doubt.

I’m just curious how that might be. I understand that if the feedback between the eccentric shaft and DME is compromised that would have an impact, I’ve just never heard anyone describe this the way you did. Did you have codes, or any other reason to indicate your sensor was failing? Thanks!

Papa Popov: This is interesting; thanks for sharing. Throughout my ownership I’ve never had a single Valvetronic or ESS code, but despite a bone-dry connector, I suspect some oil has entered my sensor. No major issues, but a bit of funky idling at times, and all the other usual suspects have been ruled out (at least mostly).

The sensor is just so damn expensive and I’ve spent so much on my car lately haha…

The idea that power could be compromised is interesting, but I’m somewhat skeptical the difference could be noticeably large in the absence of a very much failing sensor, likely with codes to boot. But that’s nothing but a guess on my part.

[ccyccm]

No codes or oil in the connector. Sometimes on hot starts, the idle would fluctuate sort of wildly and that was my only cue. After replacement, the same fluctuation happened and then very quickly would stop, and even less fluctuation the next time. I attribute that to the valvetronic system relearning and adapting to the new sensor.

As for power, now I know exactly what they mean about NA engine throttle response. The throttle feels like a scalpel and all the power is on tap all of the time.