Hello, I bought a 2008 Mini Cooper base, with 140,000 miles several weeks back and have thrown a ton of labor, parts, and cash at it. The car does not want to idle smoothly unless I unplug the intake camshaft sensor.

The only thing that makes this engine run perfectly is if I unplug the intake camshaft sensor...so I replaced it with a new sensor, but then it idled bad again........so I unplugged it again. I tried to unplug the exhaust camshaft sensor, but the car died when I drove it. I plugged the exhaust camshaft sensor back in and then unplugged the intake sensor and then it ran great again.

Here is what I tried before I found the camshaft sensor trick: Compression check is 155-160 on all 4 cylinders. Leak down is approx 80%. Did a smoke/pressure check of intake. I replaced the Mass Air Flow sensor. Drained fuel tank and replaced the fuel filter, then added fresh Premium Fuel. New air filter. New spark plugs. Removed the intake to check for carbon build up (looks brand new). Removed and swapped coils. Removed and swapped fuel injectors.

Any ideas? It is currently at the local German car mechanic because I threw in the towel! He called yesterday and said the car is running perfectly, but he has NOT done any work to the car. We just can't figure out why this very rough idle is intermittent, and always throws the P0303 Cylinder 3 Misfire Code when it runs rough. And how or why it runs awesome when the intake camshaft sensor is unplugged.

Thank you for any thoughts
Ed

 

#3 plug wire failing?

 

That was also a thought I had. However, it doesn't appear I can just replace the #3 wire. It looks like a wiring harness for the entire ignition system bundled together.

 

my mini runs bad, but better without the exhaust cam pos sensor connected also plus lots of misfiring on cyl #3 - were you ever able to fix your issue? if so what was it?
Thanks

 

Hello, thought I would add my experience of this problem to the mix at the risk of reviving an old thread.

I've got a 2011 countryman (r60) S, All 4 at 94k. It's symptoms are very similar to those described above. I replaced the timing chain and after reassembly the problem began occurring. It is best described as the engine choking out from any rpm after a brief warm-up period, it is sometimes accompanied by misfiring on cylinder no. 3. I have found that unplugging the exhaust cam sensor results in the engine running properly, and to a lesser extent unplugging the intake cam shaft sensor has a similar effect.

What else I have done. I began by resetting the engine adaptations, which had no perceivable effects on performance. I have tried unplugging other sensors including the MAF with no similar effects. I have replaced the vanos solenoids and camshaft sensors and neither made a difference. I have tried tracking down live data that is amiss to no success. The only maybe odd thing to note is that the ignition is delayed to an almost -18 degree angle while the engine is dying.

What I have not done. I have not checked the spark, compression, or vacuum leaks, but considering those would effect the engine in the same way regardless of camshaft position sensor status I do not think they have to do with the issue at hand.

If there was a resolution to the problems described above I would be interested in the solution.

 

has anyone tried replacing the valvtronic sensor , it seems to me by unplugging the intake cam sensor puts the valvtronic motor in a happy medium position to run good(defalt position). I have a pulsation going down the road like it is throttle hunting. Wait for my part in the mail. Untill then I will drive without intake sensor plugged in

 

I had similar issues and when I replaced the MAF sensor (with Bosch) it corrected that problem. I too took it to Mini Dealer and they couldn't figure it out till they swapped MAF with a car on their lot. I had better results with exhaust cam than intake cam, but not both. Your issue is the MAF.

 

Hey James, how did this work out for you? I've been having similar problems. Previous owner replaced spark plugs, timing chain, ignition coils, and gave up on it. I replaced both inlet and oulet camshafts which fixed the problem for a bit, and it came back. Sometimes taking them out and putting them back would fix it. I finally found some info on changing the crankshaft position sensor, which had it running well for about 1000miles. Now it's back to it's old tricks...hoping you got yours fixed by swapping the valvetronic sensor?

 

hi there have you ever found an answer to this amazing rough idle i have done my entire engine over too to bottom with all new parts and still the problem persist like you i remove the intake sensor and it idles perfect until next start up.....my question can i run without intake cam sensor connected?

 

Try replacing the crankshaft position sensor if you haven't already

 

I have replaced the crankshaft sensor....im wondering if its not the ecu/ dme

 

Hello Bradcccc, Was this issue ever solved? I have the same problem but runs good when I remove the exhaust side camshaft sensor. I did not find any solution here except from the person who mentioned MAF could be faulty, but it doesn't make much sense to me. Also why almost everyone who has a similar issue has misfiring in cylinder 3? Just a coincidence? (Mine misfires in 3 too)

If you are curious about my issues (2011 R55 with N16) please check my other posts. Thanks!

 

In my case the compression is good throughout, have already thrown a lot of parts (new coils, vanos solenoids, camshaft sensor, valve cover/PCV and so on. It does seem that there is no mechanical issue and it is related to either wiring fault or the DME. My mechanic suggested I check continuity from the connectors that go to the computer to the 3rd cylinder coil pack and injector. Is there a wiring diagram showing all the pins somewhere (I can also purchase if there is any software showing all the electrical details)

 

Hey there @2011clubman_justa - taking out the camshaft sensor / replacing it seemed to hide some issues for me. Not sure why, maybe just messes with the timing when removed and makes a misfire less noticeable. I thought this sensor was my issue, but I (foolishly) believed the person I bought the car from when they said they replaced the spark plugs. Alas, they did not and they were black as sin with fried tips, one was almost completely gone. I think the justa's run a bit carbon-y and maybe foul them out sooner than you'd think. You probably already changed these, but I thought it would be worth mentioning. Car is now in 111k and runs like a top (knock on wood) since the new plugs somewhere in the 80-90k range.

If not that, I also replaced the MAF sensor which also seemed to make things better for awhile, but it all seemed the car was doing its best to accommodate new parts while attempting to make a terrible spark plug work. If all sense fails, could need a carbon cleaning? I remember reading some needed that. I didn't, but definitely see the buildup when I pop the hood. Good luck

 

Hi there, Thanks for the update. So your car IS running with the camshaft sensor connected now? Your comments about carbon etc doesn't apply to me because my engine is completely rebuilt.

Here is my post for the issue AFTER the rebuild,
https://www.northamericanmotoring.co...er-no-3-a.html

and here is the post of the issue BEFORE the rebuild

https://www.northamericanmotoring.co...s-or-both.html

So now the problem is mainly the car doesnt run if the camshaft sensor is connected. I won't say it runs perfectly, but what i have learnt from here and other places is that disconnecting the camshaft sensor disables the valvetronic (VANOS) system and the computer only uses the crankshaft sensor for timing and it puts in some optimum but not perfect timing, hence no misfire but still not getting the spec'ed performance.

 

Ah I see. I might have missed something re your situation, but I had misfires I couldn't get rid of, got better with disconnected camshaft sensor or new one for a little while. In the end was a bad spark plug (though none were great). In my digging for cures, I read carbon cleaning, MAF sensor, VCG, and camshaft sensor replacement.

If your car not running at all with the camshaft sensor plugged in, that is a problem well over my head I'm afraid.

 

It misfires in cylinder 3 when the camshaft sensor is plugged in. One more comment about carbon cleaning. Justa is port injected, not direct injected as in case of Cooper S models. Direct injection engines (like VW/Audi FSI, new BMW engines, turbo models of Mini etc) have the carbon build-up issue. Of course the naturally aspirated ones do get some on the valves (especially if there is a problem!) but not like the direct injected ones.

 

In response to James Stillwell below, I have this issue of extremely rough start with the engine conking out. Starts and runs great with the Camshaft Position sensor unclipped as others below. I have swapped out the Vanos solenoids with brand new Mini OEM in hopes that would fix the issue, it did not. New CPS sensors made no difference. same with a new MAP. The adaptations would not reset correctly as the intake was only reading at 46 degrees, where it needs to be between 140-160. My last ditch attempt to fix this will be to replace the Valvetronic Position Sensor, and then reset the adaptations once again. If this is the cure for my Mini flu, I will update this post. New part coming next week. Cheers all.