2007 x5 4.8i cold start/running issues

[Junkers]

I recently purchased a high mileage(263k)X5 4.8i but its well cared for and maintained. It doesnt leak a drop or smoke and the interior and exterior are nearly mint. It currently has a few issues im trying to fix. On the first cold start in the morning the engine stumbles for a second or two. It seems to lack power and the trans like to lurch when dropping down to 1st. But the lurching goes away once the fluid temps comes up. I have a new pan, fluid and bridge seals to hopefully solve the shifting issues. I replaced the PCV disks since one was mangled and the other installed incorrectly. I pulled and cleaned the Vanos solenoids and it didnt effect it at all. I watched the data steam of the vanos system on my scan tool. Vanos position intake and vanos adaption intake 5-8 values dont fluctuate like the others. Its also throwing a P0347 "Camshaft Position Sensor "A" Circuit Low" Im going to try to replaced the sensor tomorrow. Is there anything else I should check? Im new to BMWs im more of an Audi person which is one of the main reasons i purchased this. I need a vehicle to drive while i rebuild the 3.0t engine in my A7

[ard]

Absolutely replace that sensor. They can crack/fail internally and it results in 'slop' in position detection. THis can cause VANOS position errors. (There are 5 sensors that form the main 'engine timing dataset'... Crank sensor, and two cam senosrs for each side. All the DME knows is those 5 streams coming in, and from them it has to determine engine timing, misfires, camshaft errors, vanos errors.


I dont like 3rd world aftermarket sensors. I like OE or OEM, but hard to nail that down. I usually just buy from a BMW dealer online. Saving $30 just isnt worth it.


HOW did you clean that VANOS solenoid? I use a can of carb cleaner, BLAST It while I actuate the sensor. Click Click click. You can often times hear the sound change as crap is cleaned out- from a soft, hesitant <click>, up to a crisp CLICK. But you need to actuate it. BE SURE you use the right voltage, some are less than 12V as I recall.



Finally, I think the DME will roll the vanos/cam to a safe default position when it isnt getting good data. Which would jib with your observation it doent seem to be adjusting.



Some BMW software tools have a "VANOS FUnction check" which commands the DME to move them to various positions. Usually useful for digging, although I think you have enough info for now.


GL. Report back!

[Junkers]

I cleaned the solenoids in a ultrasonic cleaner. They came out looking like new but I didn't test them. I read on here that if you turn on the ignition and let the car sit for 5 seconds before starting the stumble will go away. I tried it this morning and it works. I just don't remember their solution to this problem. Maybe a bad fuel pump. I watched the real time data of the vanos this morning and again when I got to work. All numbers are fluctuating like they should and no cam sensor code but still missing power. I was checking my scan tool for the vanos system test with the ignition on engine off the car threw a crank sensor code out of no where. Tried to start it and it just cranked. Cleared the code and it started correctly. I'm totally lost now

[Junkers]

Ordered new orings for the solenoids and going to clean them again while actuation them.

[ard]

As I wrote the DME is trying to figure out 'where' the rotating parts are, in time and space, from a stream of blips on these sensor lines... in prior motors we used to see a bad/failing cam position sensor trigger CPS errors, vanos errors AND crank errors. Then the next day be fine.


if the crank position sensor is not working I believe the DME inhibits the fuel pump.

When these sensors degrade, the signal they generate can be distorted and the DME cannot detect the position well. This can be intermittent too.


Ive not used an US bath. would think it gets in behind the plunger if in solvent and if long enough... dunno


The observation about waiting could be a 'fuel pressure building' issue.

[Junkers]

I just find it weird I haven't got the same OBD code twice. Its always something different. Almost like its an electrical or module issue. I just degreased the entire engine to inspect the harness and sensors. Going to pull all the cam and crank sensors and clean them once the solenoid oring kit comes in. I do believe i have a weak/bad fuel pump. Im unable to hear anything running with the ignition on

[Junkers]

Well, I replaced both cam sensors on the intake side with cheap Chinese ones from Amazon also replaced the vanos solenoid orings and its running well with no codes. Now have to order some oem sensors to keep as spares