My 2009 JCW during acceleration sputters or misses for about half a second and I hear a rattle coming from the engine compartment at the same time. Maybe not a rattle but a odd noise. This used to only happen once a month and recently doing it every 20 miles. Car has 30,000 miles, I did all oil changes on time, all recalls up to date, no problems with the car. No dash lights. Any ideas?

I read other posts with similar problem and some said fuel pump, 30k is awfully early for a fuel pump, but who knows. Thanks!!

 

Possibly pinging (pinking) under load, or superknock. Do you ever see the half diagonal yellow engine light come on for a few seconds at the same time? Next time you feel it look and see if it comes on briefly.

I would get the codes read and see if there are any superknock or misfire codes.

 

Has your car had the ECU tuned?

My car also stumbles once in a while under hard acceleration under large load situations in the higher gears. Mine sounds like a backfire in the intake manifold. I'm testing a few things to see it I can get rid of it.

 

My 2008 MCS had this issue. It recorded as superknock. Kind of sounded like a bb in a can followed by a quick short stall aka fuel cutoff. I went in 6 times for this issue. Total time in shop was 45 days. They cleaned the head and ports and replaced hpfp, all injectors, the turbo etc... To no avail. I forced MINI to take it back under lemon law after 3 years 11 months of ownership.

 

Wow, that's crazy, they replaced all those parts and couldn't figure out the cause. Mine doesn't do it often enough to entertain pursuing the lemon law but, it would be nice to know what the problem is.

 

I wish we could have figured it out. It was pretty scary during those times I needed to pass quickly and it stalled. I even had MINI regional rep involved on three of those visits. They even replaced a couple of valves, piston rings, reflashed software etc... I even had a loaner do the same thing. I think it's a common N14 engine problem. You notice it more at about 3,000 rpm? I'm hoping the N18 engine in my new JCW never has the issue.

If they can't fix it, there is precedent for returning it

 

Can't help you with the problem but I will say that following the MINI guidelines is not enough. When you are under warranty, MINI wants to extend the service as long as they can so they have less expense except for the small percentage of big failures. Once you are out of warranty the cost is all on you. If you go by their extended intervals you increase the risk of bigger expenses instead of reasonable expenses just to be safe. I check my oil every other tank of gas and I change it every 5000 miles. I would rather do that then have to rebuild the motor etc. Just hit 102,000 miles on my 09fJCW and all is good.

As far as the HPFP goes, MINI has a known problem with that and the warranty has been extended to I believe 120k miles.

 

Similar problem with my car. What started as what I took to be a misfire under hard acceleration became more noticable. Right now it a bit over 25,000 miles.

It actually felt and sounded like a momentary engine stop. When they did the diagnostics at the dealership, they found Super Knock codes had been generated. The high pressure fuel pump did read 5 bar, but dropped very quickly when the ignition was shut off. Evidently the pump should maintain pressure for a while. So, the pump was replaced and so far, so good.

According to RealOem, the list price for the pump is $895. Thank goodness for warranties.

 

My guess would be the fuel pump also. The cost of the fuel pump is the least of your worries. You're talking about something that pressurizes flammable liquid to thousands of psi. There are all kinds of special tools/sealants used in replacing the hpfp. Just look at the how-to in the Bentley to give you an idea. The fuel pump is actually really easy to get to as it's just on the drivers side of the engine block.

 

I believe the working pressure is around 2,000psi. While impressive, I've worked around water jet systems capable of doing 55,000psi.