Cam Position Sensor - 2001 740i

[gtfiji]

I own a 2001 740i with 82,000 miles on it. I recently had the service engine light come on so I took the car to my mechanic. The fault code stored was a cam position sensor fault on bank#2. The car had been running fiarly well but did stall once at idle. I ordered two new cam position sensors from Bavarian Autosport (top OEM part at $107 each). The sensors had larger barrels on them and had "BMW" molded onto the side of them. After installing the new sensors the car idles rough and hesitates at times.

Any ideas as to what my problem could be? All comments are appreciated.

[David325e]

How long has the car been run with the new sensors?

Are the cps positions slightly adjustable, they could be off track. Not enough to cause a no start, but enough to make timing a PITA for your comp?

[2000740]

I believe they changed the size of the barrel after 99. Did you try unplugging the battery to reset the system. It may have to get adjusted to the new readings the sensors are giving.

[gtfiji]

I ran the car for about 1/2 hour with new sensors. I will try unhooking the battery for awhile. I had not heard of that before. The DYIs I read did not mention that.

[David325e]

Yep. Why I asked about the running. The ecu will learn how the car runs, and how you drive, and alter it's 'maps' accordingly. So in other words it's still compensating for a bad cps, but it's running fine. On the e34's it used to be 1hr unplugged. But I think the e38's require less time? Try searching 'battery nap' here in the e38 section for more specifics.

Edit: when you clear it and plug the battery back up it will be running the pre-programmed maps. Might still run a little off. Much better than now, but some hesitating or lack of power, etc. Take it out for a nice drive and within and hour or so she should be purring happily.

[gtfiji]

Thanks. I will definitely try it tonight. Can you advise as to how to clear the code on my own or point me to a link?

[David325e]

Clearing a default code, the service/check engine light, just requires disconnecting the battery for about 30 seconds. If it comes back up, you still have issues.

[gtfiji]

I unhooked both battery terminals and left them diconnected overnight (14 hrs total). I just hooked them up and took the car for a drive. The service engine light did not come on at all but the car ideled a bit rough and had some lack of power when accelerating through the 2,000 rpm range. I drove about 5 miles total through a subdivision hitting a max speed of 50mph but mostly driving stop and go. Near the end of the drive the ASC+T/DSC warning light came on and a "Engine Failsafe Program" notice came on. I was able to limp home at 5mph.

The other bit of information I had left out previously was that I just had the alternator replaced after the service battery light was illuminated for about 20 miles. After getting the car back from the shop the CPS sensor fault problem started.............now this. It seems to me I having a larger underlying problem going on!

Any ideas?????

[2000740]

What voltage are you getting while driving? Do a cluster unlock and check it out. I had the engine failsafe a while ago and it was the alternator. Check the belt tensioners they may not have tightened everything properly. If your belt is loose it will slip and you will have reduced power and missing.

[Pedro Rabie]

99.999% of electrical gremlins are caused by low battery voltage.

P.

[2000740]

Also check the battery itself. A bad alternator will kill the cells in the battery.

[IcemanBHE]

kill the cells in the battery.

Just had this today.

Battery acted like it was fine...float charger acted like it was topped off...

But had a weak battery for a few months....

After 4 days of float charging, took it to get load tested...and it was a pass...but refused to output anymore than 11.9 volts.

Got me a new battery.

[gtfiji]

II took the car to my mechanic since unhooking the battery overnight did not resolve the problem. He did at great job troubleshooting the problem and did not charge me for the work. He was able to smooth out the idle by wiggling the Mass Airflow Sensor connector. The connector was not fully snapped on. Once pushed on correctly all.problems disappeared. It is possible this connection was not made correctly after the alternator replacement. I wonder if I really had a faulty cam position sensor after all.

Thanks for all the comments and input.

[edp714]

I recently replaced the alternator on 01 740i sport and also had the check engine light come on. The OBD came back camshaft position sensor bank 2. Since the car is not showing any signs of running rough or not starting, I'm thinking maybe I didn't reconnect the sensors properly. Am I on the right track or could it be something else??

[Mayorchuck]

What code are you getting?

[edp714]

P0345

[Mayorchuck]

Good. Wanted to make sure it wasn't another one that can be bad news. When this car throws a CPS code, it is usually related to that sensor and not something else. So yes, I would check your drivers side CPS wiring/connection. And welcome to the forum.

[edp714]

thank you, I reposted thinking I did something wrong in my posting. oops!

[Mayorchuck]

No worries. Probably best you started your own thread. Moderator may combine this info on your thread. Hope it's something simple.

[edp714]

Last question for today, can you tell me the difference between the M62 -TU vs M62 engine. I think mine might be the M62-TU engine and how would I know?

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Last question for today, can you tell me the difference between the M62 -TU vs M62 engine. I think mine might be the M62-TU engine and how would I know?

[Mayorchuck]

Yours is indeed a M62TU, which started with the '99 model year. Vanos timing. Check out e38.org.