Hello all,

I purchased a 2013 MCS about a month ago. It seemed to be in good condition with 56K miles.

I got a sudden misfire after coming home from a trip in the GA mountains. The engine started vibrating noticeably along with a significant loss in power. Vibration only occurred while idling or under load--accelerating from a stop or going up hill. The vibration stopped when coasting down hill.

I changed the spark plugs and switched ignition coil 2 with coil 4. I still got a P0302 after clearing the codes. I've heard the computer can misidentify the misfiring cylinder, so I suppose a bad coil could still be an issue.

Yesterday I ran a dry compression test on a cold engine. I removed all spark plugs and pulled the fuel pump fuse (F46, 20A). I tried to start the engine to be sure I got the right fuse--no start.

Results:
Cylinder 1: 160 psi
Cylinder 2: 175 psi
Cylinder 3: 175 psi
Cylinder 4: 175 psi

Now after reinstalling the fuel pump fuse, spark plugs, and ignition coils, the engine will not turn over. I've let the car sit over night and it will still not start. Gas tank is full.

I checked the spark plugs to see if they were wet from fuel. They did not appear to be wet and I saw a small amount of smoke rising from the cylinder 1 spark plug hole (first one I checked).

I'm really not sure where to go from here. Any input would be appreciated.

Thanks

 

how many times did you try to start it? sometimes you need few trails to let the gas build pressure. also, make sure you put the fuse in the right place (you never know!). lastly, spray some quick start after the elbow before the throttle body. does it start?

 

my 2007 cooper S is 200+ psi dry and 230+ psi wet on all four. Perform a leak down test to see where are you loosing compression. Dry all four
Wet all four

 

200+? Wow, I think you get some extra oil in your cylinders which increases the compression pressure. Shouldn't it be around 170?


About the subject - what do you mean by not turning over? No cranking at all, like starter isn't rotating?

 

I find that it's around 160 dry. The shorter the extension on the gauge - the higher the reading. Most important - all 4 are close and a decent reading.

 

its bored/milled head may be because of this ?

 

timski right! Consistent reading its important!
As much as I understand you can turn engine by hand and it turns by starter.
Code shows that cylinder 2 is misfiring. If compression is even in all four that means you have issues with spark or with fuel.
if its fuel it might be injector. Can of seafoam in gas tank might fix it.
If its spark its might be spark plug or coil. I would change it from one cylinder to another cylinder. Coils kinda know for failing. Its 20-30$ on amazon.

 

A bit off-topic. Are you removing in-tank fuel pump fuse? I was always curious how to do that correctly with N14 engines, that have mechanically driven HPFP's. If you stop supply of the fuel from the tank... the HPFP is still rotating. No harm to run it dry? I would definitely prefer to disable injectors instead of any fuel pumps. I even have an option to disable those from rheingold, but not sure if it works on stopped engine.
.
As of your issue - I am sure your sparks are simply wet. Try to take them out and see/smell. I know you've removed the fuse, but there's a residue pressured fuel in the rail. If that's the case, just rotate engine by starter with sparks out, so it vents itself (put your lag of gas so it's fully opens the throttle).

I had similar issue (I didn't remove any fuses) and it took few times of drying the sparks to make it run again.

 

Vepr,

I always do a compression test with the engine warmed up.
I pull out all 4 plugs - no need to pull the fuse.
Then I run the compression test on one cylinder at a time making sure to reset the gauge each time I move it to a new cylinder. It's as simple as that. Sometimes when people change the fuel filter they have issues with the car starting after.
I think it's better not to touch the fuse.

I have never had an issue doing a test.

 

200+ seems high. I've been reading that ~170 is typical for the N14.

The starter turns the engine fine--battery has plenty of juice.

I just pulled the fuse under the glove compartment. I'm pretty sure it stops the pump.


I haven't had time to do much since my original post, but I have at least narrowed down the issue--No spark!

I tested each coil with one of these set to 25:


No spark on any of the coils!? I checked each coil for continuity. I got 1.0-2.0 ohms on primary resistance and 0 ohms on secondary resistance for each coil. I've read secondary should be >1K ohms. These are the terminals I checked:

For secondary, I checked all three on the head with the spark plug terminal--nothing.

I believe it is more likely that I am doing something wrong than every single ignition coil suddenly failing.

 

Just got the Mini back form the shop. Final update for those that may have similar issues:

No-spark was due to a blown fuse (#10 in the engine bay). I must have killed it during the compression test.

Engine misfire was due to the failure of two coils. The battery was apparently weak, so they may have failed because of an insufficient supply of voltage.

I should have just replaced the coils after changing the plugs and I would have saved a lot of time and money. Of course, I probably would not have discovered the battery issue until they failed again.

 

Good to know. thanks for the update.