VANOS problem

[rowsdower]

I posted this in the N52 section but no replies, and I need to use the car soon, and more people look here so...

2011 N51 128i 6MT

I recently cleaned both VANOS solenoids while I had the top of the motor apart to do the valve cover gasket and eccentric shaft sensor. When I put everything back together, I started getting a rough idle when starting the car which would last for 5-10 seconds. It is actually more of a jumping than a rough idle - it revs between 850-900 and repeats. After it is done doing this, it suddenly revs up to about 1500 RPM and runs normally after that. It does this same thing whether the car is completely cold or up to temp. The code I am getting is "002A7C - VANOS, intake, cold start".

I originally thought that one of the solenoids was be failing or I messed it up when cleaning it, but then I cleared the codes and swapped the intake & exhaust solenoids, and the code did not follow the solenoid. Same startup behavior, same code. So now I'm trying to figure out what else might cause this code other than the solenoid itself failing. Any ideas?

[chris_flies]

Originally Posted by rowsdower

I posted this in the N52 section but no replies, and I need to use the car soon, and more people look here so...

2011 N51 128i 6MT

I recently cleaned both VANOS solenoids while I had the top of the motor apart to do the valve cover gasket and eccentric shaft sensor. When I put everything back together, I started getting a rough idle when starting the car which would last for 5-10 seconds. It is actually more of a jumping than a rough idle - it revs between 850-900 and repeats. After it is done doing this, it suddenly revs up to about 1500 RPM and runs normally after that. It does this same thing whether the car is completely cold or up to temp. The code I am getting is "002A7C - VANOS, intake, cold start".

I originally thought that one of the solenoids was be failing or I messed it up when cleaning it, but then I cleared the codes and swapped the intake & exhaust solenoids, and the code did not follow the solenoid. Same startup behavior, same code. So now I'm trying to figure out what else might cause this code other than the solenoid itself failing. Any ideas?

I'd recommend filling a quarter-tank of gas with a bottle of Techron and driving it to near-empty and then filling the tank back up and putting in another bottle of Techron. It seems to be the cure-all for N52 running issues, in many cases. Did you clear the codes?

Good luck!

[rowsdower]

I did clear the code, and each time it comes back with a SES light. I’ll try Techron for generally cleaning the fuel system but I would be very surprised if it fixed the VANOS issue.

I’ll play around under the hood some more and see if I can find a wire that’s grounding out or something. Just seems weird to me that swapping the solenoids had no effect and this started with me doing the valve cover gasket and cleaning the solenoids.

When starting, what is the VANOS up to? Does it open the intake but not use the exhaust solenoid? If both were shot, this may explain why the code did not follow the solenoid. Any thoughts from those more experienced with this system would be helpful.

[rowsdower]

I finally got INPA working and reset adaptations, which helped with the weird revving at first start but did not clear the code. The car will now start and idle normally, then after 10 seconds, will jump up in revs to about 1200 and throw the SES light and code 002A7C.

I'm at a loss here. I've read about sheared VANOS bolt heads that end up in the oil pan, but I believe that is limited to N55 engines. Also, the symptoms don't seem to match mine.

[desertman123]

Any chance it's the cam bearing ledges?

[Gizmo135i]

Try taking the vanos solenoids out and soaking them in fresh oil for a little while... (don’t get oil in the connector part), check all of the connectors on the front of the engine and make sure none are contaminated with oil, and clear the vanos adaptations again.

I’ve seen this happen several times, after changing oil filter housing gaskets, and after cleaning vanos solenoids. I’m honestly not 100% sure of the cause, but these things have seemed to remedy the issue for me in the past.

Also make sure you didn’t some how switch the connectors on the solenoids

[Havocsteve]

What exactly do you mean by shaft sensor? Was it the part with the worm gear and it connects from the top to the DME? If you did that, and didn't make sure the shaft that connects back against that worm gear is in wither the max or min position with the valves at either max or min, then your timing will be off regardless of what your doing and you'll have cold start and idle issues (happened to me so I know first hand). Make sure that shaft is at max with a lot of tension (need 2 people for the job). Then put everything back together. I didn't have this manual at time so I left it to my Indy shop. This fucking part cost me around 2grand final total after I messed it up the first time. Also check to make sure the wiring to the sensor and DME is without oil on it. That will cause issues as well.

https://www.newtis.info/tisv2/a/en/e...-gear/CyzwchK9

[Gizmo135i]

Originally Posted by Havocsteve

What exactly do you mean by shaft sensor? Was it the part with the worm gear and it connects from the top to the DME? If you did that, and didn't make sure the shaft that connects back against that worm gear is in wither the max or min position with the valves at either max or min, then your timing will be off regardless of what your doing and you'll have cold start and idle issues (happened to me so I know first hand). Make sure that shaft is at max with a lot of tension (need 2 people for the job). Then put everything back together. I didn't have this manual at time so I left it to my Indy shop. This fucking part cost me around 2grand final total after I messed it up the first time. Also check to make sure the wiring to the sensor and DME is without oil on it. That will cause issues as well.

https://www.newtis.info/tisv2/a/en/e...-gear/CyzwchK9

He has an n52, it’s different

[Havocsteve]

Originally Posted by Gizmo135i

He has an n52, it’s different

Scratch what I said then ahaha. Those shaft sensors though are very finicky. I had to go back to the Indy shop to re-calibrate mine and then it was finally running perfect.

[rowsdower]

Originally Posted by Gizmo135i

Also make sure you didn’t some how switch the connectors on the solenoids

This was it. I took a photo of the engine prior to digging into it. After I read your post, I went out to the car to compare and sure enough the wires were switched. I swapped them and did a few iterations of resetting adaptations and clearing codes until everything was back to normal. Took it for a drive long enough to warm up the car, started it several times, everything is normal and no codes. I'm relieved but annoyed at myself for not checking the simplest stuff first.

For anyone else doing this, the wire coming from the intake side of the engine goes to the exhaust solenoid, and vice versa. Don't assume that the wire from the intake side goes to the intake solenoid like I did...


Thank you all for your help!

[chris_flies]

Originally Posted by rowsdower

This was it. I took a photo of the engine prior to digging into it. After I read your post, I went out to the car to compare and sure enough the wires were switched. I swapped them and did a few iterations of resetting adaptations and clearing codes until everything was back to normal. Took it for a drive long enough to warm up the car, started it several times, everything is normal and no codes. I'm relieved but annoyed at myself for not checking the simplest stuff first.

For anyone else doing this, the wire coming from the intake side of the engine goes to the exhaust solenoid, and vice versa. Don't assume that the wire from the intake side goes to the intake solenoid like I did...


Thank you all for your help!

Glad you found a solution! I'll learn from you for when I clean my solenoids.