I bought a 2010 base model Cooper (N12, 102K) as a project. It had a misfire on cylinder #2. I'll bypass all the diagnostics and jump right to the problem: Damaged/Cracked exhaust valve. So I pulled the head and sent it to a machine shop for a full valve job and inspection. Got the head back and put it all back together, and for good measure I also installed a new timing chain kit (chain, guides, tensioner, etc). Now I keep getting the following code as I start the engine: P0341 Camshaft Position Sensor A Circuit Range/Performance Bank 1 or Single Sensor.

Guys, I can't figure this one out. The engine will start right and seems to run fine, although there is a lot of clatter from the top end - more than I would expect. I have not tried to drive it, so I don't know how it would perform under a load.

What I've tried so far:

1. Clear codes and restart engine
2. Swap intake/exhaust cam sensors
3. Check wiring and connections
4. Checked oil level
5. Viewed data stream with engine running and there is a signal coming from the intake cam sensor, but I don't know how to interpret the data

An observation: I recently did the timing chain/guides swap on another Mini (2011 with 140K miles) and it went smoothly. The engine started right up afterwards and ran like a champ. I discovered on this 2010 that there are actually two positions on the flywheel that the lock will fit into - they're 180º apart. I thought maybe I had somehow gotten the crank of out position when I cleaned the carbon from the tops of the pistons, so I loosened the crank hub bolt (yes, I'll replace it) and rotated the cams 180º. That did seem to help it run better, but the code and clatter are still there.

What am I missing? It doesn't seem likely to be a problem with the sensor, since swapping them didn't make a difference. The only thing that makes sense is that the timing is off somehow, but it's pretty hard to get it wrong with the crank and cam locks installed. Is there something else I can check, or can someone help me understand how to read the live data?

 

Flywheel only has one locking hole. It makes two full revs for every one cam rev, so it can be locked with the cams 180 out.

After timing is set initially, a check is to remove tools, rotate engine (always CW, NEVER CCW) at least one full rev, lock flywheel, partially reinstall cam tools and measure gaps. Are your gaps within spec? It's not uncommon for the chain to have "kinks" during initial setting and loosen during rotation. The fact that it "did seem to help it run better" helps warrant this check.

"Clatter from the top end" can be caused by lifters and / or rockers. PITA to verify but there should be minimal movement of rockers while at TDC --- valves closed. At least verify all rockers have about the same movement. And ensure the replaced valve doesn't have a loose rocker.

Finally, if it starts and seems to run OK, maybe the oil hasn't circulated fully thru all the lifters. These engine's are known for many things, including engine noise.

 

Now that you say it, it dawns on me that (duh!) the cams rotate 1/2 the speed of the crank. So yes, it is possible to the cams to be 180º out with the crank locked.

What is an acceptable amount of gap for the cam tools. I'll definitely check that.

I'l also take a look at the other items mentioned and see if anything jumps out at me.

Thanks!

 

Part of the NewTIS procedure ---

 

Thanks! The thickest feeler gauge I have is .8mm and it's not even close to being able to fit in either gap. That tells me the timing must be OK according to the measurements in the TIS.

I checked the rockers and all feel about the same. I just gave each one a "wiggle test" and all the exhaust rockers have tiny amount of play. I didn't feel anything on the intake side.

I'm going to button it back up and start it again, but I'm pretty sure the code will be back. What else could be going on?

 

Can't help with the code --- never had that one.

Maybe an extended run will quiet the "clatter" --- get all the air bubbles out of the lifters.

Hopefully someone else can help ---

 

UPDATE: None of the above made a difference. I forgot to mention before that the idle also slowly wanders up and down for about 30 seconds after the engine is started. And it really sounds bad when I rev it.

I swapped the VANOS actuators to see if it would make a difference. It didn't.

The cam sensor is definitely working because I can see the values changing in the live data stream.

Seems to me that it has to be in the timing, but it's spot on.

 

Did you fix this?? How?

 

No. I took it to another shop and they recommended swapping the cylinder head. It's been there almost 3 months and even after swapping the head, the error is still there. But it does sound better. Shop now thinks it might be a fault in the ECU. When I finally get it back from them, I'll send off the ECU to have it checked.

 

I believe this has to do with the timing chain install. There is too much tension on the chain and it is now allowing the cams to move independently. I ran into thos issue when rebuilding an 07 R56 base model. The tensioner barely applies tension to the chain. There will be a very small amount of slack between the cam sprockets. If the chain is too tight, they can move!
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