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Please help! 09 Mini Cooper Convertible with N12 (Base model) idle hunting have to pump the gas pedal to get it to start etc..

3054 Views 13 Replies 4 Participants Last post by  Mike8765

I bought this car to fix up for my daughter. It has 76000 miles on it. When I got it you had to pump the gas like crazy to get it to start then it would idle really bad, rps would go up-down-up-down etc then it would die. The first thing I did is look at the spark plugs and they were very worn. I replaced them and then it would idle a little smoother but will still rev up/down/up/down etc. I did some reading and one person said to check the crankcase breather hose. It was broken completely in two so I thought hey, this will be a cheap fix. I ordered the hose, had to remove the intake manifold to change it so I replaced the intake manifold gaskets and cleaned the throttle body while I had it apart. It didn't have that annoying whistling sound from the crack in the hose anymore but it still idled the same. Next I removed both vanos solenoids and hooked 12volts to each of them, one clicked like it should, the other was more of a soft thunk. I cleaned both of them and put them back, no change. I bought 2 brand new ones and replaced them both, no difference. I tried my innova code scanner and it doesn't work with this car so I went to Oreillys and used theirs. The only codes were 2783-Misfirings several cylinders, 2773-Misfirings cyl 2, 2777-Misfirings Cyl 3, 277B-Misfirings cyl 4, 277F-Misfirings Cyl 2, 2782-Misfirings several cylinders, 2772-Misfirings Cyl 1, 277E- Misifirings Cyl 2, 2781-Misfirings several cylinders, and 2771 Misfirings cyl 1. I drove the car around and it has plenty of power, once in a while when I go to take off it would hesitate then take off really fast, also when I let off the gas at certain speeds it bucks really hard like a manual transmission car does when you slow down without pushing in the clutch (This one is automatic trans) I put some fresh gas in it and changed the oil with a good synthetic 5w30. In my desperation I starting unplugging different things one at a time so see what difference it made and I noticed it makes absolutely no difference if I unplug the mass airflow sensor, plug that goes down to the front o2 sensor, either vanos solenoid (allthough I did hook one up with it out of the car and I'm pretty sure I heard it click once) I tried unhooking the cam and crank sensors one at a time. whichever one is closest to the firewall will occasionally make the car die when I plug it back in. The one in front make no difference. I thought maybe the maf was bad even though I cleaned it so I bought a brand new one and it didn't help. The car is almost driveable if I turn on the AC to keep the idle up a little but I don't feel comfortable letting my daughter drive it this way. It does not have any death rattle from the timing chain tensioner at all. I took it to my mechanic because I thought maybe the timing could be off since these are notorious for that but he checked the compression and it was within spec and he said that should rule out head gasket or timing. I'm not so sure about that because I noticed some smoke coming from the tailpipe this morning when I started it. I had him hook his Snapon Soleus scanner to it and he said in live mode It was misfiring prettu much constantly on Cyl 1, periodically on cyl 2 and 3, he said he didn't see a misfire on 4 but there is a code for it so it must misfire at least once in a while. He did give me the following data from his scanner in case someone on here could make something of it:
VANOS Exhaust Spread Actual Value (cr) 120 Inlet Camshaft position (cr) 691 Exhaust camshaft positon (cr) 281 Adapt Valve inlet Camshaft (cr) 0 Adapt Valve exhaust camshaft (cr) 0 Eccentirc Shaft setpoint value 6526 Eccentric shaft actual value 179 Valvetronic relay - closed

ANOS inlet spread Setpoint value (cr) 115 VANOS inlet spread actual value 116 VANOS exhaust spread setpoint value (cr) 115 VANOS exhaust spread actual value (Cr) 120 Inlet Camshaft position (cr) 102 Adapt Value inlet camshaft (cr) 0 Adapt value exhause camshaft (cr) 0

Today I checked the fuel pressure, it was around 52 and as soon as I shut off the car it would slowly drop once it got down to 40 I unhooked the gage so I don't know if it would've kept dropping.

I also replaced that diaphram on top of the valve cover that is common to fail and it made no difference.

I'm hoping with all of this information someone can point me in the right direction. I did check all of the fuses in both fuse boxes and there is voltage to the MAF sensor.

People keep telling me to replace the timing belt kit just to see if it fixes it but I can't afford to spend $300 labor and the cost of the parts if it won't help. All of the other parts I have thrown at it were cheap.
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Started bucking hard?
like it would not go into the lower gear for some reason or another. I would have to assume that the transmission is in sync with the engine via the computer module.
miss fire on plug one. Well you could buy one fuel injector and swap that out for number 1 and see if it makes a difference. I don't know if it would be like coil packs(where you buy one and replace the one that is misfiring and take the one that was there and swap it for cylinder 2. When the end result hoping to be that it wakes up the coil that was unresponsive in cylinder number 1) where just one activates the others that were having problems before. That is a truth. And is why most people that I have talked to advise to only buy one coil pack at a time.
Even cheaper you could buy a fuel injector o ring and seals kit or a hardware installation kit; not having to replace any injectors and re sealing the injectors to the head. With that I would advise what they call "O-ring silicon grease" not sealant! and use that with the seals in the kit. This product is specifically designed for this application of installing fuel injectors. Just don't use it on the Teflon seals which I don't think you have due to the lower compression of your naturally aspirated engine. Just on the rubber seals.
Wow you checked alot of stuff there. What happens sometimes with a crankcase breather tube which I am assuming is coming off of your valve cover; is the part where the breather hose attaches to a plastic neck of the valve cover end breaks and would cause a rough start and rough time. Rough start and rough running are some key traits to the mini engine I know that much when it comes to problems they are specific and the same things that can occur. like the plastic neck that the breather tube goes into cracks on the underside so you would need to remove the valve cover and inspect the underside of the plastic neck on the valve cover.
Rough Start rough running also applies to the vanos solenoids which you have replaced. quality not really being important but I like ECS tuning Vanos solenoids for my mini due to the fact they hand assemble them in there shop and are quite a bit cheaper. Another things is to check your vacuum hose underneath the intake manifold and make sure they are connected. buy the small zip ties they sell at your local hardware store. And zip tie those little rubber vacuum hose. Check for engine vacuum and compression. But those little hoses can come off and the plastic reservoir does fail on some minis and would cause a dying idle situation.
Cleaning up the throttle body does not always work that is just how it is when they are plastic. So you might have to purchase a new. Off hand you can check that the throttle body is working by getting someone to start the car for you while you look at the butterfly on the inlet of the throttle body and it should go through it's entire range of motion.
you have to take the inlet pipe off of course to see that!
Right now I really cannot think of anything else that may be problem in respect to what you said about not being able to change the chain. It may not be a chain issue anyway.
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as have misfires in 3 cylinders and mainly number 1 ie number is gearbox end and gets the hottest so has a habit if leaning out over time this causes high bore temps,, this does damage to valve stem seals and valves on the n12 engines also stretched timing chain adds to this issue going by live data on set points and adaption i would say a timing mismatch is there, another way to tell if chain is nailed is mileage they dont do 100k on same chain its more around 60k ish, run low on oil engines are worse,
i might be suspect of the vanos sprockets might be free wheeling that can cause that having to rev it to keep it running , compression test and leak down test needed also worth pulling manifolds off when doing leaking down test and spray liquid in to each port lookng for bubbles from valve seats when charged with air,, all big jobs
If you have tried everything else and you are certain timing is ok (I guess you have already found out N12 is famous for the death rattling), then I would try cleaning the fuel injectors. It's pretty easy, look on Youtube and you'll find a 'how-to'. Use carb cleaner and a cable directly in the battery to blow carb cleaner through it - here is an example:

The key is to make sure you have pressure on the injector so that the carb cleaner is pressed through the injector when to attach the battery. NB - only connect the battery in short 'bursts' so you don't fry the solenoid valve inside.

Good luck.
Update, this weekend I removed the fuel rail and took each injector out and cleaned it. I took some brake line hose that fit tightly over the inlet of the injector, then fit the next size hose down inside of it, and kept doing that until I got down to the size of the straw that came with my carb cleaner spray. I put hear shrink between each hose transition to keep a tight seal so I wouldn't lose any pressure. Then I made a circuit with a 555 timer IC to pulse injector like the car would and activated it while spraying the carb cleaner into each injector one at a time. One of them did have a crappy spray pattern at first but it was nice an even when I got done. The others were fine. After I put the injectors back in I put some lucas fuel injector cleaner in the gas tank and filled it with 91 octane gas. It idled slightly better when I started it but still went from around 950rpm to 1150 or so back and forth. I took it for a long drive to let the higher octane fuel and the cleaner circulate through it. I noticed more power and smoother acceleration right away. The bucking when I let off the gas was gone. After 20 minutes of driving it ran not perfect, but passable. I could come to a stop and the idle barely varied, you really had to listen for it and you couldn't feel it in the car at all like before. I drove around town for a while and it was pretty good. After I took the car home and let it sit to cool. It wouldn't even start when I pumped the gas pedal. I ran the battery dead trying, finally I hooked the jumper cables from my truck to the car and worked with it some more. I finally got it to start by holding the gas pedal to the floor but the idle was back to bouncing again. Someone on another forum mentioned something about the thermostat housing, thermostat, or the coolant temp sensor. I'm leaning towards trying that next since it runs pretty good when the engine is fully warmed up but I can't find the post. If anyone has any more thoughts with this new info I would appreciate it. I still need to check the throttle body as someone on here mentioned but it got dark before I got to mess with it anymore. Thanks for all of the replies. I really appreciate it.
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would lean towards throttle body intermittent or the wiring to it, first off, or maybe the vvt high lift valve position sensor, this lives on end of head gearbox end its the black sensor with a strange looking plug on top its held to head by 3x10mm bolts ,, its a two part sensor if remove it and look in the hole you will see a coil that is bolted to end of lift shaft by a allen bolt in its middle , when these fail it will cause all kinds of strange running from stalling and also throw eml for 02 sensors and cat and rich running as it starves the engine of air and will make the cat glow bright red after 5 minutes of running is common, might also be cps sensor maybe,, need a diagnostics scanner to see what its all doing ,
I would check the injectors again. If you have a problem with dirt or rust particles in your gas tank, the injector cleaner could have loosened even more of it and clogged your injectors (again). I am not saying it is not something else, but I would check that as well.
... and filled it with 91 octane gas.
You may also read this:

91 Octane Fuel for Your MINI is Bad! | PERRIN Performance

I have no idea if this applies to your car, but I always run mine on 95 octane (standard gasoline in Norway)
these engines run best on 98ron anything less will hurt them, even more so on the turbo cars
Update... replacing all 4 injectors got the car to where it's at least driveable but the hard bucking when I let off the gas when going slow is driving me insane. Sometimes it doesn't do it but when it does it's bad. Like a stick shift when you let the clutch out and you're in a higher gear than you should be. Any suggestions?
Not sure if I have read everything above, but have you checked the fuel pump? If it seems to be linked to fuel (have to trottle hard, replaced injectors), could it be the pump? It is located under the rear seat, just pull it out and you will see a metal cover that needs to be removed. Dependent on the model of car you have there may also be a fuel filter as part of the fuel pump that can be replaced (NB - some models have a permanent filter that is not meant for replacing, you will see what is applicable for your car when you open it)
Thanks for the reply. Fuel pressure is good. I fixed most of the other issues. It starts without hitting the gas every time now and the idle still hunts occasionally but not very often. The bucking is bad though. I have decided to sell this piece of crap but I wanted to fix the bucking first. Thanks
Not sure if this is related to your problem, but after replacing the timing chain on my N12 the motor was running really rough, even if I made sure everything was in the right positions. It turned out to be the adaptive electronics that needed to be reset; this car is supposed to have a system where it "learns" gradual need for adjustments, e.g. if the timing becomes a little off, and I suspect it will also do something if the solenoid valves becomes cloggy and unable to adjust the timing as it should. The way to do it was to reset/delete socalled "adaptations" with a software tool. After doing that my car has run smooth
Not sure if this is related to your problem, but after replacing the timing chain on my N12 the motor was running really rough, even if I made sure everything was in the right positions. It turned out to be the adaptive electronics that needed to be reset; this car is supposed to have a system where it "learns" gradual need for adjustments, e.g. if the timing becomes a little off, and I suspect it will also do something if the solenoid valves becomes cloggy and unable to adjust the timing as it should. The way to do it was to reset/delete socalled "adaptations" with a software tool. After doing that my car has run smooth
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