Can a bad cam position sensor cause stalling?

[BimmerM3inGA]

I'm trying to diagnose a stalling problem on a friend's '03 525iT with 75K miles. It runs fins when the engine is cold and also runs fine at highway speeds. But once it's warmed up, it will stall at low engine speeds. It will idle all day in neutral and it will run down the road all day. But as soon as you let off the gas, it dies. If parked, it will often die as soon as it's shifted into gear (it's an automatic). Sometimes it will stay running, but will die as soon as I try to give it some gas.

The check engine light was on, so I scanned it and got back the code P0341 "Camshaft Position Sensor A Circuit Range/Performance". Would this be on the intake or the exhaust cam, and would that cause it to stall?

[jnyost]

I've unplugged the ones on my 540 and it seems to run fine without them, but the I6s are more temperamental and will die or have rough running.

I believe "A" is the intake, but some on here state you should replace both. It's up to you.
http://eactuning.com/parts/product_details/12147539165
http://eactuning.com/parts/product_details/12147518628

[jamfool]

Yes it would make the car stall.
Since a very specific code has been thrown for this, I would be pretty confident to change the part in question. If there was a combination of codes, it would be more complicated and would not necessarely mean this sensor is at fault.

The sensor is cheap enough to throw a new in, then take it from here.

If the problem persist, check the ECU for operations and voltage. A failed ECU will cause the same kind of problem you are describing here.

[BimmerM3inGA]

I believe "A" is the intake, but some on here state you should replace both. It's up to you.
http://eactuning.com/parts/product_details/12147539165
http://eactuning.com/parts/product_details/12147518628

I think I will go ahead and do both. What is the difference between "ORIGINAL BMW" and "O.E.M."? I mean, besides the price!

[Alpines]

Lets Google, OEM, Original Equipement Manufactuer. Done was that sooo hard?

The difference between OEM and Bmw Part is Bmw Logo on the Box it comes with, and higher price. OEM parts are same thing that the dealer sells but comes Straight from the manufactuer

[Cyrix2k]

I've unplugged the ones on my 540 and it seems to run fine without them, but the I6s are more temperamental and will die or have rough running.

I believe "A" is the intake, but some on here state you should replace both. It's up to you.
http://eactuning.com/parts/product_details/12147539165
http://eactuning.com/parts/product_details/12147518628

If I'm not mistaken, the cam sensor is only required for sequential fuel injection. The ecu will probably revert to batch fire without the sensor which basically means that yes, it will run fine without it.

[BimmerM3inGA]

Lets Google, OEM, Original Equipement Manufactuer. Done was that sooo hard?

Jeez! Why does everybody have to be such a smart ass? The dude sells the parts and I was just asking him (not you) if there is any real difference. Yes, I have heard of Google and am capable of using it. But that's not always the source of the most conclusive answer.

As a newbie, you should get used to the idea that this forum is a place to ask questions beyond what may turn up in a Google search. If you feel a question is a stupid one, you are not required to give an answer.

[PatrickW]

on the I6 motor it will go into limp mode if the sensor fails while the car is running but if you disconnect it alltogether im not sure, just had a problem with a new sensor I got from bavauto and it kept giving me a cam position sensor connection error and would run in limp mode IF the car would start...

[BimmerM3inGA]

I'm going to go ahead and replace both sensors. My Bentley manual doesn't have a procedure to test them, or I'd do that and just replace the faulty one. Neither one looks all that hard to replace, so it's not like it's a lot of extra work to just do them both.

[jamfool]

If I'm not mistaken, the cam sensor is only required for sequential fuel injection. The ecu will probably revert to batch fire without the sensor which basically means that yes, it will run fine without it.

No, the car will definitely stall with a missing CPS...

[Piemanse39t]

I've changed my sensor(oem part) and not had any problems since.Just do it.

[Cyrix2k]

I've unplugged the ones on my 540 and it seems to run fine without them, but the I6s are more temperamental and will die or have rough running.

I believe "A" is the intake, but some on here state you should replace both. It's up to you.
http://eactuning.com/parts/product_details/12147539165
http://eactuning.com/parts/product_details/12147518628

]No, the car will definitely stall with a missing CPS...[/B]

It seems we have a disagreement. All I know is that the ECU only needs the crank position sensor to run, but I'm not sure if bosch actually implemented a limp mode. Judging by jnyost's comments, they did (at least on the 540).

[pshovest]

A cam position sensor is required for ignition as well as VANOS timing. These are 4-cycle engines. Cams turn at 1/2 the engine speed. A crank position sensor can't distinguish between TDC on compression stroke and TDC on exhaust stroke. DME needs to know this in order to fire plugs correctly.

What's not clear is that after engine starts does DME check cam position sensor on every cam revolution or can it simply fire plugs every 720 degrees of crankshaft rrotation and ignore the cam position sensor.

I've never heard of a limp mode for cam or crank position sensors.

Paul S
BMW CCA 69606

......All I know is that the ECU only needs the crank position sensor to run,..........

[Cyrix2k]

A cam position sensor is required for ignition as well as VANOS timing. These are 4-cycle engines. Cams turn at 1/2 the engine speed. A crank position sensor can't distinguish between TDC on compression stroke and TDC on exhaust stroke. DME needs to know this in order to fire plugs correctly.

What's not clear is that after engine starts does DME check cam position sensor on every cam revolution or can it simply fire plugs every 720 degrees of crankshaft rrotation and ignore the cam position sensor.

I've never heard of a limp mode for cam or crank position sensors.

Paul S
BMW CCA 69606

No it doesn't. It only needs to know the crank speed to fire... my e30 runs with *only* a crank position sensor. That is with batch fire fuel injection and wasted spark ignition - which, as you probably know, fires plugs on both the intake & exhaust cycle (the "wasted" spark). A cam sensor is only required for sequential fire so it is very possible the DME could have a limp mode.

As for this happening in practice, it does
http://www.automotiveforums.com/t59294.html

I took out the cam sensor and found that the magnet has come off. The book says the car will not run without a signal but it does.

annnd

The car will just batch fire the injectors with out the magnet in place no reall big deal but the dreded yellow light. I still get 360 miles per tank freeway at 220k miles. I need to know how fix this too.

As I said above, I'm not sure how the bosch dme handles a fault with the cam sensor, but it certainly is possible to implement a limp mode that will let the car run without it.

[BimmerM3inGA]

The car doesn't appear to be going into a limp home mode. It just dies. The trick to getting it going is to rev it slightly (maybe 750-900 RPM), then drop it into gear. Once underway, it runs normally. At least until you forget to not let completely off the gas!

Unless that is the limp home mode. But performance isn't reduced in any way, which is how I'd expect it behave in limp home mode.

[pshovest]

Which E30......318?
Certainly wasted spark systems only need a crank position sensor....but where's the evidence E39's use wasted spark? E39's have all the sensors necessary to avoid wasted spark.

If DME senses a severe enough misfire, it disables the fuel injector. I wouldn't call that a limp mode.

Paul S
BMW CCA 69606

No it doesn't. It only needs to know the crank speed to fire... my e30 runs with *only* a crank position sensor. That is with batch fire fuel injection and wasted spark ignition - which, as you probably know, fires plugs on both the intake & exhaust cycle (the "wasted" spark). A cam sensor is only required for sequential fire so it is very possible the DME could have a limp mode.

As for this happening in practice, it does
http://www.automotiveforums.com/t59294.html


annnd


As I said above, I'm not sure how the bosch dme handles a fault with the cam sensor, but it certainly is possible to implement a limp mode that will let the car run without it.

[BimmerM3inGA]

I believe "A" is the intake, but some on here state you should replace both. It's up to you.
http://eactuning.com/parts/product_details/12147539165
http://eactuning.com/parts/product_details/12147518628

Thanks! I just ordered them.

[Cyrix2k]

Which E30......318?
Certainly wasted spark systems only need a crank position sensor....but where's the evidence E39's use wasted spark? E39's have all the sensors necessary to avoid wasted spark.

If DME senses a severe enough misfire, it disables the fuel injector. I wouldn't call that a limp mode.

Paul S
BMW CCA 69606

sorry, I missed this somehow. The e30 is a 325e running megasquirt 2/extra.

The DME for the 540 runs full sequential fuel injection & spark by default iirc, but my point is that it is possible to run with only a crank sensor as a limp mode should the cam sensor go bad. Other ECUs are known to do this, but I don't know if the e39 dme does. jnyost's comments make me think that a limp mode (which would be wasted spark) does exist for the 540.

[ataie]

was running perfect, then out of nowhere it dies when the car comes to stop. it's a manual. drives awesome, and I'm not getting a code. have to have one foot on gas constantly when slowing down to keep it running.

any ideas?

[BimmerM3inGA]

Most likely the idle control valve. That is a classic symptom of a stuck or failed unit.

[FP5241]

All I have to contribute is that when my Cam Sensor went out, the car would start and then shake and die. New sensor, vanos seals and a VCG change and I have not had an issue since.

[ataie]

problem fixed: I had one of the seats repaired at a shop and they disconnect the battery. when the battery was connected they did not allow the DME to initialize by simply turing the ignition for a few seconds prior to starting. I did that, the car is running find as it did before. I suddenly thought of that and tried it and that's what it was. thanks for the feedbacks

[BimmerM3inGA]

Cool. Glad you got it sorted out and it was something simple!

[lyonne]

The non-vanos 540 (M62) will certainly run without a cam position sensor. I have unplugged mine. I could hardly tell a difference.

[jamfool]

Ok just sharing my experience here in case it helps anyone...

Recently my car would stall too or it took me 4-5 times to start before he would keep the idle.

Then more serious problems started to appear out of the blue one day.

There was no code thrown and there was voltage variations (Jumping up and down) from the ECU.

We also noticed she was stalling once the engine temp would reach 100C

ECU was changed, CPS was changed etc....but at the end it turned up it was the Pulse Generator, which plugs into the Gearbox.

We bought an aftermarket one initially (Bilstein), the car would not even start at all. Had to source from the dealer, car was fixed.

The Pulse generator in those cars does not throw codes when it is faulty.
The sensor was like 60 quids from the dealer if I remember well.